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Cover: Vasey's Paradise, 1984. Ground water, discharging from the Redwall Limestone, feeds the spring that cascades into the Colorado River, 31.7 miles below Lees Ferry, Arizona. Photograph by R. D. Mac Nish, U.S. Geological Su.-vey. Riding down a short distance, a beautiful view is presented. The river turns sharply to the east, and seems inclosed by a wall, set with a million brilliant gems. What can it mean? Every eye is engaged, every one wonders. On coming nearer, we find fountains bursting from the rock, high overhead, and the spray in the sunshine forms the gems which bedeck the wall. The rocks below the fountain are covered with mosses, and ferns, and many beautiful flowering plants. We name it Vasey9s Paradise, in honor of the botanist who traveled with us last year. John Wesley Powell August 9, 1869 Director, U.S. Geological Survey, 1881-94 From Powell, J. W., 1875, Exploration of the Colorado River of the West and its tributaries explored in 1869, 1870, 1871, and 1872: Washington, D.C., U.S. Government Printing Office, p. 76. National Water Summary 1984 Hydrologic Events, Selected Water-Quality Trends, and Ground-Water Resources By United States Geological Survey United States Geological Survey Water-Supply Paper 2275 DEPARTMENT OF THE INTERIOR DONALD PAUL MODEL, Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director UNITED STATES GOVERNMENT PRINTING OFFICE: 1985 For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402 FOREWORD National Water Summary 1984 is the second of an annual series of reports prepared by the U.S. Geological Survey that describes the conditions, trends, availabili- ty, quality, and use of the Nation's water resources. The first report, National Water Summary 1983 Hydrologic Events and Issues, documented a broad range of water-resources issues from both a national and State perspective. Prominent among those issues was the increasing importance of ground water as a source of water supply in many parts of the country, the widespread concern over declining ground-water levels, and issues associated with ground-water quality. Ground water is one of the Nation's most valuable resources, and many find it one of the most difficult to understand. It provides 35 percent of the fresh water withdrawn for municipal water supplies, 97 percent of rural drinking water, 40 percent of irrigation water, and about 26 percent of the water used by industry, exclud- ing thermoelectric power uses. Ground water is now the source of drinking water for more than 50 percent of the population. The widespread availability of ground water in most parts of the country, its dependability in times of drought, and its relatively good quality have led to an increase in ground-water withdrawals of nearly 190 percent since 1955. In response to the growing awareness of the impor- tance of ground-water resources, the 1984 National Water Summary presents an overview of the occur- rence, distribution, and use of ground water in each State, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, the Trust Territory of the Pacific Is- lands, Saipan, Guam, and American Samoa. Each of the many aquifers which comprise the Nation's ground-water systems has a distinct hydrogeologic set- ting, flow pattern, quality of water, and degree of use; consequently, analyses of aquifer conditions are com- plex and require much detailed information. Because of that complexity, and because of the formidable array of information on ground-water quality, it is not practical to address in this volume both the physical characteris- tics of the Nation's aquifers and the chemical quality of water flowing in them. Accordingly, consideration of ground-water quality, including the natural occurrence of chemical constituents in ground water and the con- tamination of ground water by man-induced processes, will be presented in a future edition of the National Water Summary, In the meantime, the U.S. Geological Survey will continue to emphasize programs that characterize the important aquifers of the country and to develop ground-water quality information at local, regional, and national scales. Specific examples of these pro- grams are the Federal-State Cooperative Program, the Regional Aquifer-System Analysis Program, and the Toxic Waste-Ground-Water Contamination Program. In aggregate, these activities are producing much of the hydrologic, hydraulic, and chemical information that is essential to define aquifer systems and to understand the movement, alteration, and eventual fate of contami- nants introduced into those systems. In addition to the description of ground-water systems, the 1984 National Water Summary reviews significant hydrologic and water-related events that occurred during the year and presents articles that expand on a number of specific water issues that were discussed in the 1983 report. These include an analysis of the occurrence of nitrate in ground water, an expla- nation of ground-water declines in selected areas of the country representing different hydrogeologic environ- ments, and discussions of the distribution and trends of several water-quality constituents in major rivers. The reports in the National Water Summary series are designed to inform government officials, water- resource managers, and the general public of various aspects of the hydrologic system from which our water supplies are obtained. This is a broader audience than we usually address in our technical hydrologic and geologic reports. Therefore, we are particularly inter- ested in receiving comments regarding the contents, style, and usefulness of this report and suggestions for future reports in this series. Such remarks may be addressed to the Chief Hydrologist, U.S. Geological Survey, 409 National Center, Reston, VA 22092. Director National Water Summary 1984 Contents vii Contents Foreword- ---------------------------------------------- v Overview and Introduction --------------------------------------- 1 Overview of National Water Summary 1984 ------------------------------- 2 Introduction to National Water Summary 1984 (D. W. Moody and E. B. Chase) ------------- 5 Hydrologic conditions and water-related events, water year 1984 ----------------------- 7 Overview of water year 1984 hydrologic conditions and related events (H. F. Lins, J. C. Kammerer, andE. B. Chase)- ---------------------------- 8 Seasonal summaries of hydrologic conditions, water year 1984 (H.F.Lins)- --------------- 22 Fall season October to December 1983 ------------------------------- 22 Winter season January to March 1984 ------------------------------- 24 Spring season April to June 1984- --------------------------------- 26 Summer season July to September 1984 ------------------------------- 28 Selected hydrologic events, water year 1984 ------------------------------- 30 Rising lake levels ----------------------------------------- 30 Rise of Great Salt Lake, Utah (TedArnow) --------------------------- 31 Rise of Devils Lake, North Dakota (G. J. Wiche)- ------------------------ 34 Floods --------------------------------------------- 36 Record late-spring 1984 floods in New England (R. A. Fontaine) ------------------ 37 June 1984 floods on the Missouri River and tributaries (I. L. Burmeister) -------------- 40 Spring 1984 runoff in the Colorado River basin (D. L. Collins) - ------------------ 42 Water quality ------------------------------------------ 44 Selenium in the San Joaquin Valley of California (S. /. Deverel) ------------------ 45 Hydrologic perspectives on water issues ---------------------------------- 47 Introduction -------------------------------------------- 48 Water-quality issues ----------------------------------------- 49 Sediment in rivers of the United States (R. H. Meade and R. S. Parker) ---------------- 49 Loads and concentrations of dissolved solids, phosphorus, and inorganic nitrogen at U.S. Geological Survey National Stream Quality Accounting Network stations (J.E.Kircher,R.J.Gilliomf andR.E.Hickman) -------------------------- 61 Trends in concentrations of dissolved solids, suspended sediment, phosphorus, and inorganic nitrogen at U.S. Geological Survey National Stream Quality Accounting Network stations (R. A. Smith and R.B.Alexander)- -------------------------------- 66 Dissolved solids Case studies ----------------------------------- 74 Dissolved solids in the Colorado River basin (J. E. Kircher) --------------------- 74 Dissolved solids in the Arkansas River basin (J. D. Stoner)- -------------------- 79 Pesticides in rivers of the United States (R. J. Gilliom)- ----------------------- 85 Overview of the occurrence of nitrate in ground water of the United States (R. J. Madison and J. O. Brunett) ----------------------------------------- 93 Water-availability issues --------------------------------------- 106 Ground-water-level changes in five areas of the United States (L.J.Mann)- -------------- 106 Declining ground-water levels and increasing pumping costs: Floyd County, Texas A case study (J. E. Schefter) ----------------------------------------- 114 State summaries of ground-water resources -------------------------------- 117 Introduction (R. C. Heath) ------------------------------------ 118 Alabama ---------------- 123 Kansas ----------------- 217 Alaska ----------------- 129 Kentucky ---------------- 223 Arizona ---------------- 135 Louisiana- --------------- 229 Arkansas ---------------- 141 Maine ----------------- 237 California- --------------- 147 Maryland and the District of Columbia - - - 243 Colorado ---------------- 153 Massachusetts -------------- 249 Connecticut- -------------- 161 Michigan ---------------- 255 Delaware ---------------- 167 Minnesota --------------- 261 Florida ----------------- 173 Mississippi --------------- 269 Georgia- ---------------- 179 Missouri ---------------- 277 Hawaii ----------------- 185 Montana ---------------- 285 Idaho ----------------- 193 Nebraska ---------------- 291 Illinois ----------------- 199 Nevada- ---------------- 297 Indiana- ---------------- 205 New Hampshire ------------- 303 Iowa- ----------------- 211 New Jersey --------------- 309 Viii National Water Summary 1984 Contents State summaries of ground-water resources Continued New Mexico- -------------- 317 Tennessee- --------------- 391 New York- --------------- 323 Texas ----------------- 397 North Carolina ------------- 329 Trust Territory of the Pacific Islands, North Dakota -------------- 335 Saipan, Guam, and American Samoa - - - 403 Ohio- ----------------- 341 U.S. Virgin Islands - ----------- 409 Oklahoma --------------- 347 Utah- ----------------- 415 Oregon- ---------------- 355 Vermont ---------------- 421 Pennsylvania -------------- 361 Virginia ---------------- 427 Puerto Rico- -------------- 367 Washington- -------------- 433 Rhode Island -------------- 373 West Virginia -------------- 439 South Carolina ------------- 379 Wisconsin- --------------- 447 South Dakota -------------- 385 Wyoming ---------------- 453 Glossary, national drinking-water regulations, and water conversion factors ------------------ 459 Glossary ---------------------------------------------- 450 National drinking-water regulations ---------------------------------- 465 Water conversion factors --------------------------------------- 466 Geologic age chart - ----------------------------------------- 457 Figures 1. Map showing streamflow in water year 1984 as a percentage of normal (1951 -80) in the United States and Puerto Rico ---------------------------------- 9 2. Map showing precipitation in water year 1984 as a percentage of normal (1951 -80) in the United States and Puerto Rico ---------------------------------- 9 3. Graphs showing monthly discharges for selected rivers in the United States for water years 1983 and 1984 compared with monthly median discharges for the reference period 1951 to 1980- ------ 10 4. Graphs showing month-end storage of selected reservoirs in the United States for water years 1983 and 1984 compared with median of month-end storage for reference period 1961 to 1982 ------- 11 5. Map showing location or extent of significant hydrologic and water-related events in the United States, Puerto Rico, U.S. Virgin Islands, Guam, and American Samoa, August 1983 to September 1984 --------------------------------------- 13 6. Maps snowing hydrologic conditions during the fall season, October to December 1983 ----------- 22 7. Maps showing hydrologic conditions during the winter season, January to March 1984 ----------- 24 8. Maps showing hydrologic conditions during the spring season, April to June 1984 ------------- 26 9. Maps showing hydrologic conditions during the summer season, July to September 1984 ---------- 28 10. Landsat thematic mapper image of Great Salt Lake, Utah ----------------------- 32 11. Graphs showing changes of water level and dissolved-mineral concentrations of Great Salt Lake, Utah, 1847 to 1984 --------------------------------------- 33 12. Photograph of Great Salt Lake showing entrance to Antelope Island Causeway underwater, June 16, 1984 ----------------------------------------- 33 13. Map showing the drainage basin of Devils Lake, N. Dak. - ----------------------- 34 14. Graph showing water levels of Devils Lake, N. Dak., 1867 to 1983 - ------------------- 34 15. Photograph showing flooding along Route 7 in New Milford, Conn., caused by overflow of the Housatonic River, May 31, 1984 --------------------------------- 36 16. Photograph showing aftermath of flooding in central Vermont, June 7, 1984 --------------- 37 17. Index map showing areas of New England flooded in 1984 by late-spring floods -------------- 38 18. Graph showing monthly occurrence of annual peak discharges for the period of record of the Salmon River near East Hampton, Conn., and the Piscataquis River near Dover-Foxcroft, Maine ----- 39 19. Index map showing area of June 1984 floods on the Missouri River and tributaries ------------- 40 20. Photograph showing aftermath of flooding of the Missouri River at Rulo, Nebr., June 18, 1984 ------- 41 21. Index map of the Colorado River basin ------------------------------- 42 22. Photograph showing flow being released from Glen Canyon Dam, Ariz., May 23, 1984 - ---------- 43 23. Photograph of the Kesterson Reservoir, San Joaquin Valley, Calif., showing the San Luis Drain and evaporation ponds ------------------------------------- 44 24. Index map showing the location of the existing and the proposed San Luis Drain, San Joaquin Valley, Calif. ------------------------------------ 45 National Water Summary 1984 Contents ix Figures Continued 25. Map showing average concentration of suspended sediment in rivers and average discharge of suspended sediment at the mouths of selected rivers of the conterminous United States ---------- 50 26. Map showing average concentration of suspended sediment in rivers and average discharge of suspended sediment at the mouths of selected rivers of Alaska- -------------------- 50 27. Graphs of annual discharge of suspended sediment at six stations on the Missouri River and two stations on the Mississippi River showing the effects of reservoirs on downstream sediment loads, 1939 to 1982 --------------------------------------- 52 28. Graphs of annual discharge of suspended sediment at six stations on the Rio Grande showing the effects of reservoirs on downstream sediment loads, 1906 to 1983 ------------------- 53 29. Graphs showing annual discharge of water (1905-64) and suspended sediment (1911-79) in the Colorado River at Yuma, Ariz. ---------------------------------- 55 30. Maps showing average suspended-sediment discharge of major rivers in Georgia and the Carolinas during two periods, about 1910 and about 1980, that indicate the decrease in sediment loads caused by several reservoirs constructed during the intervening years --------------- 56 31. Graph showing suspended-sediment discharge in the lowermost 300 miles of the Mississippi River at three different stages of river flow ------------------------------- 57 32. Diagrams showing sources, sinks, and storage of sediment in the drainage basin of Coon Creek, Wis., 1853 to 1938 and 1938 to 1975 ---------------------------------- 58 33. Graphs of annual suspended-sediment discharge of three rivers showing the frequencies of suspended-sediment discharges within individual years and the importance of infrequent heavy storms in producing large sediment loads -------------------------------------- 59 34. Map showing dissolved-solids loads and mean annual concentrations at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981- ----------------------------------------- 62 35. Map showing phosphorus loads and mean annual concentrations at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981 ---------- 63 36. Map showing inorganic nitrogen (nitrate plus nitrite) loads and mean annual concentrations at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981 ----------------------------- 64 37. Map showing trends in dissolved-solids concentrations at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981 ---------- 67 38. Graph showing increase of salt application as a highway deicing chemical in the United States, 1947 to 1983 - - 67 39. Map showing trends in suspended-sediment concentrations at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981 ---------- 68 40. Map showing trends in total phosphorus concentrations at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981 ---------- 71 41. Map showing trends in inorganic nitrogen (nitrate and nitrite) concentrations at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981 - - - 72 42. Graph showing median yield of inorganic nitrogen at National Stream Quality Accounting Network stations in relation to atmospheric deposition rate of nitrate in precipitation for the 18 water-resources regions of the conterminous United States ----------------------------- 73 43. Pie chart showing source of dissolved solids in the Colorado River basin ----------------- 74 44. Map showing maximum, mean, and minimum dissolved-solids loads for 26 stations in the Colorado River basin, 1965 to 1983- ----------------------------------------- 76 45. Map showing maximum, mean, and minimum dissolved-solids concentrations for 26 stations in the Colorado River basin, 1965 to 1983 --------------------------------------- 77 46. Map showing trends in dissolved-solids concentrations at 26 stations, in the Colorado River basin, 1965 to 1983- ----------------------------------------- 78 47. Map showing maximum, mean, and minimum dissolved-solids loads for 18 stations in the Arkansas River basin, 1968 to 1982- ----------------------------------------- 79 48. Map showing maximum, mean, and minimum dissolved-solids concentrations for 18 stations in the Arkansas River basin, 1968 to 1982 --------------------------------------- 82 49. Map showing trends in dissolved-solids concentrations at 18 stations in the Arkansas River basin, 1968 to 1982 - 83 50. Map showing location of stream-sampling stations in the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Monitoring Network in the conterminous United States, 1975 to 1980- ----------------------------------------- 85 51. Graph showing trends in national use of herbicides and insecticides on major crops, 1964 to 1982 - ------ 86 52. Graph showing frequency of detection of organochlorine insecticides in water and bed-material samples from stations in the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Monitoring Network, 1975 to 1980 ------------------------------------- 87 53. Graph showing frequency of detection of organophosphate insecticides in water samples from the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Monitoring Network, 1975 to 1980- ------- 90 National Water Summary 1984 Contents Figures-Continued 54. Generalized flow diagram showing sources, movement, and reaction of nitrogen in soils and ground water - - - 94 55. Simplified diagram of the biological nitrogen cycle showing some environmental important reactions of nitrogen 94 56. Map showing nitrate-nitrogen distribution in ground water of the United States and Puerto Rico ------- 97 57. Graph showing distribution of three ranges of nitrate-nitrogen concentrations in well water with well depth- - - 98 58. Map showing areas of the conterminous United States where water-table decline or artesian water-level decline in excess of 40 feet in at least one aquifer has occurred since development began ---------- 107 59. Hydrograph showing water levels in three observation wells in an alluvial basin aquifer near Mendota, Calif., 1935 to 1983- -------------------------------------- 108 60. Hydrograph showing water levels in observation wells in the sandstone aquifer at Elmhurst, III., and the dolomite aquifer at Itasca, 111., 1953 to 1980 ---------------------------- 108 61. Hydrograph showing water levels in an observation well in the "2,000-foot" sand at Baton Rouge, La., 1943 to 1983- ----------------------------------------- 109 62. Sketch showing saltwater front, water-level contours, and location of fault in the "2,000-foot" sand in the Baton Rouge, La., area ----------------------------------- 109 63. Hydrographs showing water levels in observation wells in the middle Potomac aquifer, 1943 to 1984- ----- 110 64. Map showing approximate area in South Dakota where wells in the Dakota aquifer flowed freely at the land surface before development (about 1881) and at the present time (1983) - ---------------- 111 65. Hydrograph showing water levels in a well in the High Plains aquifer, Floyd County, Tex., 1940 to 1984 - - - - 114 66. Graph showing estimated pumping costs at an observation well in Floyd County, Tex., 1952 to 1981- ----- 115 67. Map showing ground-water withdrawals in 1980 for the United States, Puerto Rico, and the U.S. Virgin Islands ----------------------------------- 119 State summaries of ground-water resources Each summary has Figures 1-2. Map showing 1. Areal distribution of principal aquifers 2. Areal distribution of major ground-water withdrawals and hydrographs showing trends in ground-water levels Tables 1. Chronology of significant hydrologic and water-related events, August 1983 to September 1984 ------- 12 2. Peak discharges at selected stream sites caused by New England storm, May 28 to June 3,1984 - ------- 38 3. Discharge of suspended sediment to the coastal zone by 10 major rivers of the United States, about 1980 ------------------------------------------ 51 4. Mean annual water discharge, dissolved-solids load, and dissolved-solids concentration for 26 stations in the Colorado River basin, water years 1965 to 1983 ------------------------ 75 5. Mean annual water discharge, dissolved-solids load, and dissolved-solids concentration for 18 stations in the Arkansas River basin, water years 1968 to 1982 ------------------------ 80 6. Selected characteristics and uses of pesticides monitored by the U.S. Geological Survey- U.S. Environmental Protection Agency Pesticide Monitoring Network, 1975 to 1980 - ---------- 88 7. Summary of detections of pesticides in water and bed sediments at the U.S. Geological Survey- U.S. Environmental Protection Agency Pesticide Monitoring Network stations, 1975 to 1980 ------- 89 8. Summary of nitrate-nitrogen concentrations in ground water, by State ------------------ 96 9. Summary of fresh ground-water withdrawals, by State ------------------------- 120 State summaries of ground-water resources Each summary has Tables 1-2. 1. Ground-water facts (Not included in Trust Territory of the Pacific Islands, Saipan, Guam, and American Samoa) 2. Aquifer and well characteristics (Table 1 in Trust Territory of the Pacific Islands, Saipan, Guam, and American Samoa) Photographic credits: All photographs by U.S. Geological Survey personnel unless otherwise identified. Photographs not identified in text are: Page 1, Hydrologist monitoring discharge from an irrigation pump north of Sterling, Colo. Well pumps 2,700 gallons per minute. (Photograph by D. E. Reed.) Page 7, San Luis Drain to Kesterson National Wildlife Refuge, San Joaquin Valley, Calif. (Photograph by S. J. Deverel.) Page 47, Analyst operating automated wet chemical analyzer for nitrogen at U.S. Geological Survey's Denver Central Laboratory. (Photograph by D. E. Reed.) Page 117, Old pump, east of Brighton, Colo. (Photograph by D. E. Reed.) Overview and Introduction National Water Summary 1984 Overview OVERVIEW OF NATIONAL WATER SUMMARY 1984 Water year 1984 was a year of extreme hydrologic conditions. For the third consecutive year, precipita- tion and resulting runoff were well above long-term averages in most of the Nation and as much as 400 percent above average in the Southwest. National flood damages during the year were the third highest in a 10-year period (1975-84) an estimated $3.5 to $4 bil- lion. In many of the larger river systems, monthly stream discharges were above normal, as they have been for the last 2 water years, and, with the exception of a few reservoir systems, end-of-month reservoir storage also remained above normal. The Great Salt Lake reached its highest level since 1873 as a result of these conditions. During a 9.6-foot rise from September 1982 to July 1984, the area of the lake expanded by 600 square miles (an increase of 35 percent), resulting in an estimated $212 million in damages to recreational facili- ties and industrial installations built on the exposed lake bed during former lower levels. Other lake levels in closed basins of the Western United States also have risen over the past few years, thereby flooding com- munities, recreational facilities, and agricultural lands. In contrast to this predominant pattern of wet condi- tions, several areas of the country, mainly west Texas and Hawaii, have experienced persistent droughts. Most recently, very dry conditions existed in parts of northern Montana. These hydrologic conditions and 100 specific events are reviewed in the "Hydrologic Conditions and Water-Related Events, Water Year 1984" part of the 1984 National Water Summary. Although it is not an event in the sense of a flood or a pollution spill, the discovery of relatively high and toxic concentrations of selenium in irrigation return flows along the west side of the San Joaquin Valley of California is a notable example of how human activities can affect water quality. Preliminary investigations indicate that irrigation in the valley has dissolved materials from the soil, and the dissolved materials have accumulated in ground and surface water. As a result, concentrations of selenium, which naturally occur in minute amounts in the soil, have reached toxic levels in the Kesterson National Wildlife Refuge. Water managers generally agree that nonpoint- source pollution will require more attention in the years ahead if further improvements in surface-water quality are to be achieved. Similarly, point and nonpoint sources of ground-water pollution will need to be con- trolled to protect aquifers that may be used for future water supplies from contamination. As a contribution to the discussion of these issues, the "Water-Quality Issues Section" of the 1984 National Water Summary contains a national analysis of the distribution of and trends in suspended sediment, dissolved solids, nitro- gen, phosphorus, and pesticides in major rivers and nitrate in ground water. Sediment occurs in rivers as a natural consequence of geologic processes; these processes, however, maybe accelerated greatly by human activities such as forest clearing, farming, surface mining, and urban or rural development. Although the erosion of soils under a specific set of conditions can be estimated, it remains difficult to predict how much soil eventually will be delivered to a stream because sediment may be stored on hillslopes or in stream valleys for periods of time ranging from a few days to hundreds of years. This storage complicates attempts to relate changes in ero- sion rates and soil-conservation practices to suspended- sediment concentrations in rivers. Suspended-sediment concentrations also are influenced by reservoirs that act as sediment traps and thereby greatly reduce the net transport of sediment downstream; for example, sedi- ment discharges to the Gulf of Mexico by the Mississippi River are now less than one-half of what they were 30 years ago. In the last several decades, seaward transport of sediment in the Colorado River and the Rio Grande almost has been halted. Another aspect of sediment transport is that a large part of the long-term sediment load is carried by a few very large, but infrequent, floods. These floods further complicate attempts to estimate the long-term loads from relatively short records of sediment transport. Because fluvial sediments adsorb toxic substances, knowledge of sedi- ment transport processes provides important insights into the fate of toxic substances in the aquatic environ- ment. Data from the U.S. Geological Survey National Stream Quality Accounting Network (NASQAN) stations for water years 1975 to 1981 (October 1974 to Septem- ber 1981) show about equal numbers of stations with increasing and decreasing suspended-sediment concen- trations. Decreasing concentrations of suspended sedi- ment in the Missouri River basin may be related to the trapping effects of reservoirs that were constructed in the 1950's and 1960's. Trends in suspended-sediment concentration appear to correlate well with estimates of cropland-erosion rates. For example, in river basins where cropland-erosion rates exceed 2.5 tons per acre per year, the stations with increases in suspended-sedi- ment concentrations outnumber those with decreases. Dissolved-solids concentrations generally reflect the distribution of rocks and soils, human activities, and quality of atmospheric deposition. Streams draining the National Water Summary 1984 Overview granitic rocks in New England, for example, contain concentrations of dissolved solids in the tens of milli- grams per liter, whereas streams draining heavily irri- gated areas with salt-bearing shales in the Southwest may have dissolved-solids concentrations in the thou- sands of milligrams per liter. Dissolved-solids loads, on the other hand, reflect concentration and flow volume. Thus, some of the highest loads may be associated with rivers that have relatively low concentrations of dis- solved solids but large flow volumes. High concentra- tions and loads of phosphorus and nitrogen compounds that are found in the Mississippi River basin, especially in the Midwestern States, and in rivers of the Southwest are thought to reflect the distribution of agricultural activities in these regions. Widespread increases in dissolved-solids concentra- tions between 1975 and 1981, for the most part, may be due to increases in irrigated agriculture and the in- creased use of salt as a highway deicing chemical in many Northeastern and North-Central States. Con- versely, declines in dissolved-solids concentrations in the Colorado River basin may be due to improved irrigation practices and other salinity control measures. Phosphorus concentrations increased and decreased at about equal numbers of NASQAN stations between 1974 and 1981. Decreases in the Great Lakes and Upper Mississippi regions probably are attributable to major pollution-control efforts in these areas during the late 1970's. Other phosphorus-concentration patterns ap- pear to be related closely to those for suspended sedi- ment and reflect the tendency for phosphorus to adsorb to the surface of sediment particles. Inorganic nitrogen (expressed as nitrate plus nitrite) concentrations at NASQAN sites show widespread in- creases between 1974 and 1981, especially in the Eastern and Northwestern United States. The ratio of the number of increases to decreases in concentrations varies greatly with the types of land use and the magni- tude of erosion rates upstream of the measuring sites; the highest ratios occur in basins where croplands contribute the most to soil erosion. A 38-percent in- crease in nitrogen fertilizer applied to agricultural lands between 1975 and 1981 may account for the increases in inorganic nitrogen concentrations observed in basins that include large areas of croplands. Another source of inorganic nitrogen, which may prove to be significant, is atmospheric deposition. However, concentrations and loads of inorganic nitro- gen and other constituents cannot be reliably attributed to specific sources without more detailed basin analysis. Results from the analysis of almost 3,000 surface- water samples and nearly 1,000 bed-material samples from the Pesticide Monitoring Network, which was operated by the U.S. Geological Survey and the U.S. Environmental Protection Agency from 1975 to 1980, show that fewer than 10 percent of the water samples and fewer than 20 percent of bed-material samples contained detectable levels of the 22 pesticides for which analyses were made. Although the small number of detections is due, in part, to the difficulties of sampling and measuring very small concentrations of pesticides, the low frequency of detections suggests that the 22 pesticides do not occur in many rivers at concentrations that consistently exceed water-quality criteria. The disposal of human wastes through septic sys- tem discharges and agricultural activities, including fertilizing of crops and raising livestock, may be the two largest sources of nitrate contamination of ground water throughout the United States. Of more than 124,000 wells for which nitrate values are available, more than 24,000 (20 percent) had water with maximum nitrate-nitrogen concentrations greater than 3 milli- grams per liter (mg/L), which, for the purpose of this report, is considered to be indicative of the effects of human activity on the ground water. About 8,200 (6 percent) of these wells had water with maximum ni- trate-nitrogen concentrations that exceeded the U.S. Environmental Protection Agency's regulatory limit of 10 mg/L for drinking water. In most instances, elevat- ed nitrate concentrations occurred in water from wells in shallow aquifers although long-term increases of nitrate in deep aquifers are possible where the aquifers are recharged by nitrate-rich water from shallow aqui- fers or from the land surface. In the section "Water-Availability Issues," the his- torical changes in ground-water levels in several areas of the country are described. These areas are the San Joaquin Valley, Calif., Chicago, 111., area, Baton Rouge, La., Franklin, Va., area, and Dakota aquifer of South Dakota where ground-water levels have de- clined 40 feet or more in at least one aquifer since development began. In the Floyd County, Tex., area, the costs of water, due to declining ground-water levels and increasing energy costs, have risen about 220 per- cent relative to the index of prices that farmers received for their crops over the 30-year period 1952 to 1981. The "State Summaries" part of the 1984 National Water Summary describes the occurrence, use, and general quality of ground-water resources for each State, the District of Columbia, Puerto Rico, the U.S. Virgin Islands, the Trust Territory of the Pacific Is- lands, Saipan, Guam, and American Samoa. Nation- wide, ground-water withdrawals range from less than 1 percent of the total water withdrawals in the District of Columbia to 85 percent in Kansas. Ground-water with- drawals constitute more than 50 percent of the total withdrawals in 10 States. By far, the largest use of ground water is for irrigation. Each State summary consists of the following com- ponents: (1) introductory remarks highlighting the importance of ground water and the geologic framework of the ground-water system, (2) a table showing the amount of ground water used for different purposes in relation to total water use, (3) a map National Water Summary 1984 Overview showing the extent of principal aquifers, (4) a table listing the principal aquifers and data on water-supply wells, (5) a map showing the major areas of withdrawals and hydrographs showing the long-term response of the aquifers to withdrawals or the effects of climatic changes, (6) a brief description of State ground-water- management activities including names of management agencies and reference to ground-water laws and regula- tions, and (7) selected references that pertain to the State's ground-water resources. The emphasis of these State descriptions is on the distribution of major aquifers and their use. Ground- water quality is mentioned in general terms and where the quality has a major influence on ground-water development. National Water Summary 1984 Introduction INTRODUCTION TO NATIONAL WATER SUMMARY 1984 By David W. Moody and Edith B. Chase The initial volume in the annual National Water Summary series (U.S. Geological Survey, 1984) intro- duced a chronology of hydrologic and water-related events to document their importance to human activities and also outlined a number of water issues of concern to the Nation. This second volume, National Water Sum- mary 1984 Hydrologic Events, Selected Water-Quality Trends, and Ground-Water Resources, continues the chronology of events and presents additional informa- tion on several issues discussed in the 1983 volume. The 1984 National Water Summary is organized in three parts. The first part, "Hydrologic Conditions and Water- Related Events, Water Year 1984," provides a synopsis of the hydrologic conditions and water-related events that occurred during the 1984 water year (October 1, 1983-September 30, 1984). Streamflow variations are compared to precipitation, temperature, and upper-air atmospheric pressure for the four seasonal quarters of the year to relate surface-water flows to climatic condi- tions. The second part, "Hydrologic Perspectives on Water Issues," contains two sections. In the section titled "Water-Quality Issues," the occurrence of sedi- ment, dissolved solids, nutrients, and pesticides in the Nation's streams are discussed. Recently compiled information is used to show the distribution and trends of these constituents and to relate them to various natural sources and human activities. The occurrence and sources of nitrate in ground water also are dis- cussed. The section entitled "Water-Availability Issues" provides hydrologic explanations for changes in ground-water levels in several areas of the country. The articles in this part of the report complement a number of other reports, published during the past year, which provide information on the water quality of the Nation's rivers. The 1982 National Fisheries Survey (Judy and others, 1984), cosponsored by the U.S. Fish and Wildlife Service and the U.S. Environmental Pro- tection Agency, provides an assessment of biological conditions in a statistical sample of river segments throughout the United States. The U.S. Environmental Protection Agency also sponsored an evaluation of the progress of water-pollution control efforts (Association of State and Interstate Water Pollution Control Ad- ministrators, 1984), an overview of nonpoint-source pollution (U.S. Environmental Protection Agency, 1984a),and the 1982 National Water Quality Inventory (U.S. Environmental Protection Agency, 1984b). Other recent studies that examine water resources from a national perspective include the 14th annual report of the U.S. Council on Environmental Quality (1983), the Conservation Foundation's (1984) State of the Environ- ment report, and the Office of Technology Assessment's (1984) Protecting the Nation's Ground wa- ter from Contamination. The third and final part of the report, "State Summaries of Ground-Water Resources," summarizes for each State, the District of Columbia (combined with Maryland), Puerto Rico, the U.S. Virgin Islands, the Trust Territory of the Pacific Islands, Saipan, Guam, and American Samoa, the distribution, characteristics, and uses of principal aquifers. (The term "State" as used throughout the report is all inclusive of these geographic areas.) Each summary contains maps that show the location of aquifers and major areas of ground-water withdrawals and tables that describe the characteristics of the aquifers and present data on ground-water withdrawals. These descriptions of ground-water resources were prepared by the U.S. Geological Survey offices in each State. Technical terms used in the report are defined in the Glossary. Selected references are given at the end of each article and State summaries to supplement the information provided. Numerous references are made to the National Drinking-Water Regulations; as an aid to the reader, these regulations follow the Glossary. A conversion table of water measurements and a geologic age chart also are provided for the reader's conveni- ence. ACKNOWLEDGMENTS National Water Summary reports, because of their scope, are necessarily the work of many individuals. The coordinators of the 1984 National Water Summary wish to acknowledge the assistance of water-resources organizations in each State for their review of the descriptions of State ground-water resources and the assistance of the following Federal agencies, who pro- vided unpublished data and advice in preparing parts of this report: National Oceanic and Atmospheric Administration, National Weather Service Tennessee Valley Authority U.S. Army Corps of Engineers U.S. Bureau of Reclamation U.S. Bureau of Land Management U.S. Coast Guard, National Response Center U.S. Environmental Protection Agency U.S. Fish and Wildlife Service U.S. Soil Conservation Service The authors of individual articles and State ground-water summaries are identified within the re- port. Richard H. Johnson, John S. McLean, Andrew 6 National Water Summary 1984 Introduction M. Spieker, and Lindsay A. Swain coordinated the preparation of the State summaries. David A. Aronson, Bruce L. Foxworthy, Kenneth J. Lanfear, Perry G. Olcott, Robert S. Roberts, and Michael Turtora re- viewed the text and illustrations. Janet N. Arneson coordinated the assembly of the manuscript. Although individual credit is not feasible for all reviewers, graphic specialists, and typists who participated in the prepara- tion and publication of this report, their cooperation and many contributions are gratefully acknowledged. Overall preparation of the 1984 National Water Sum- mary was directed by David W. Moody, John N. Fischer, and Edith B. Chase. SELECTED REFERENCES Association of State and Interstate Water Pollution Control Administrators, 1984, America's clean water The States' evaluation of progress 1972-1982: Washington, D.C., Association of State and Interstate Pollution Con- trol Administrators, 2 vol. Conservation Foundation, 1984, State of the environment, an assessment at mid-decade: Washington, D.C., The Con- servation Foundation, 586 p. Judy, R. D., Jr., Seeley, P. N., Murray, T. M., Svirsky, S. C., Whitworth, M. R., and Ischinger, L. S., 1984, 1982 National fisheries survey, v. 1, Technical report, initial findings: U.S. Fish and Wildlife Service, Report No. FWS/OBS-84/06, 140 p. Office of Technology Assessment, 1984, Protecting the Nation's groundwater from contamination: U.S. Con- gress Office of Technology Assessment, v. I, Summary and findings, OTA-O-233, 242 p.; v. II, Appendixes, OTA-O-276, p. 243-503; Summary, OTA-O-234, 23 p. U.S. Council on Environmental Quality, 1983, Environmental quality 1983, 14th annual report of the Council on Environmental Quality: Washington, D.C., U.S. Gov- ernment Printing Office, 341 p. U.S. Environmental Protection Agency, 1984a, Report to Congress Nonpoint source pollution in the U.S.: Washington, D.C., U.S. Environmental Protection Agency, Office of Water Program Operations, Water Planning Division. __1984b, National water quality inventory, 1982 report to Congress: U.S. Environmental Protection Agency, Re- port EPA 440/2-84-006, 63 p. U.S. Geological Survey, 1984, National water summary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. Hydrologic Conditions and Water-Related Events, Water Year 1984 8 National Water Summary 1984 Hydrologic Conditions and Events OVERVIEW OF WATER YEAR 1984 HYDROLOGIC CONDITIONS AND WATER-RELATED EVENTS By Harry F. L/ns, John C. Kammerer, and Edith B. Chase Surface-water hydrologic conditions and many wa- ter-related events result principally from climatic fac- tors. The following annual and seasonal summaries of hydrologic conditions for water year 1984 are, therefore, described in a climatic context. Streamflow and precipitation are shown on maps for a water-year overview. They also are presented on a quarterly basis in the seasonal summaries where they are supplemented by maps showing temperature as a percentage of normal values and mean atmospheric pressure conditions near 10,000 feet (ft). The distribution of high and low pressure areas across the United States at about 10,000 ft, recorded in terms of the 700-millibar (mb) pressure surface, influences the distribution of surface tempera- ture, precipitation and, thus, streamflow. Usually, floods and droughts that persist throughout a season will be observed in conjunction with persistent high- or low-pressure conditions in the upper atmosphere. Inas- much as these maps depict conditions averaged over a 3-month period, ephemeral events, such as a single flood resulting from an individual storm, may not be associated easily with prevailing upper-air conditions. The data used in preparing these summaries were taken from a number of publications. These include the National Oceanic and Atmospheric Administration's publications Climate Impact Assessment, United States', Daily Weather Maps, Weekly Series', Monthly and Seasonal Weather Outlook', Storm Data; and Weekly Weather and Crop Bulletin (prepared and published jointly with the U.S. Department of Agriculture); and the U.S. Geological Survey's monthly National Water Conditions reports. Streamflow conditions across the United States during water year 1984 followed closely the pattern of normal to above-normal conditions experienced during the previous year. Indeed, with only minor differences, even the core areas of greatest departure from mean conditions persisted between each of the two periods. Although there tended to be fewer extreme or extraordi- nary flooding events, such as those experienced along the Gulf Coast in the winter of water year 1983, the frequency of more moderate floods was greater. This was especially true in the Middle Atlantic and New England States. Interestingly, despite the geographical similarity in the patterns of annual streamflow departures that characterized the two periods, a major atmospheric phenomenon believed responsible, in large part, for the higher than normal runoff conditions in water year 1983 Figure 1. Streamflow in water year 1984 as a percentage of normal (1951-80) in the United States and Puerto Rico. (Source: Compiled by H. C. Tang from U.S. Geological Survey data.) ^, did not exist in water year 1984. Whereas the weather and climate, hence streamflow, of North America in water year 1983 was influenced considerably by the unusually intense El Nifto Southern Oscillation (ENSO) of 1982-83, virtually all aspects of ENSO had ended by the fall of water year 1984 (Bergman, 1984). Why, then, did these two periods exhibit such similar patterns of streamflow? The answer appears to be that, even though the primary characteristics of ENSO in the tropical Pacific Ocean (that is, elevated sea surface temperatures, reversals in sea level pressure fields, and perturbations in both lower and upper level winds) had dissipated by the fall of water year 1984, other atmos- pheric features influencing North American weather and climate, not uniquely associated with ENSO occur- rences, did not. For example, atmospheric circulation at the 700-mb level (about 10,000 ft), which is closely associated with surface weather patterns, had very similar mean seasonal patterns in each of the 2 years. Similarly, the patterns in each of the other three seasons exhibited close agreement in each of the 2 years; even though there was considerable within-year (season- to-season) variation. The pattern of annual departures from normal or average streamflow conditions for water year 1984 appears in figure 1. Three broad areas of above-normal flows stand out along with two smaller areas of below- normal flows. Above-normal runoff occurred across the Great Basin and into the Central Rockies, in the middle and lower Missouri River valley, and throughout many of the States along the Atlantic coast. Below- normal runoff persisted in western Montana, central and southern Texas, and in Hawaii. These patterns match quite well the distribution of precipitation anom- alies for the same period (fig. 2). In general terms, despite the acute drought that occurred in several areas, water year 1984 was one of abundant to excessive streamflow in most of the United States (figs. 3 and 4). This condition is indicated clearly Figure 2. Precipitation in water year 1984 as a percentage of normal (1951-80) in the United States and Puerto Rico. (Source: Compiled by H. F. Lins from National Oceanic and Atmospheric Administation, National Weather Service data.) * National Water Summary 1984 Overview 1984 Water Year 9 Line shows points of equal percentage. Number shows percentage of normal (1951- 80) annual streamflow so Line shows points of equal percentage. Number shows percentage of normal {19S1- 80) annual precipitation PUERTO RICO C£?.040 MILES 10 National Water Summary 1984 Hydrologic Conditions and Events EXPLANATION .- Monthly discharge - Median of monthly discharges for 1951-80 reference period 800 Columbia River at The Dalles, Oregon Drainage area, 237,000 mi2 C/5 Missouri River at Hermann, Missouri Drainage area, 528,200 mi2 ONDJFMAMJJASONDJFMAMJJAS Mississippi River at Keokuk, Iowa Drainage area, 119,000 mi2 0 N D J F M A M J JASONDJFMAMJ JAS 100 60 40- 20 0 Sacramento River at Verona, California Drainage area, 21,257 mi2 ONDJFMAMJJASONDJFMAMJ JAS 1983 1984 Susquehanna River at Harrisburg, Pennsylvania Drainage area, 24,100 mi2 ONDJFMAMJJASONDJFMAMJJAS 6 300 St. Lawrence River at Cornwall, Ontario near Massena, New York Drainage area, 299,000 mi2 ONDJFMAMJJASONDJFMAMJJAS Ohio River at Louisville, Kentucky Drainage area, 91,170 mi2 ONDJ FMAMJJASONDJ FMAMJJAS 2000 3600 1200 800 400 0 8 Mississippi River at Vicksburg, Mississippi Drainage area, 1,144,500 mi2 ONDJFMAMJJASONDJFMAMJJAS Apalachicola River at Chattahoochee, Florida Drainage area, 17,300 mi2 ONDJFMAMJJASONDJFMAMJJAS 1983 1984 Figure 3. Monthly discharges for selected major rivers in the United States for water years 1983 and 1984 compared with monthly median discharges for the reference period 1951 to 1980. (Source: Compiled by H. C. Tang from U.S. Geological Survey data.) National Water Summary 1984 Overview 1984 Water Year 11 I 160 EXPLANATION - Month-end storage - Median of month-end storage for 1961-82 reference period 160' 120- 40- Lake McConaughy. Nebraska (IP) Maximum capacity 1,948,000 acre-ft £o 160 ONDJFMAMJJASONDJ FMAMJ JAS Upper Snake River, Idaho-Wyoming (MP) Maximum capacity 4,401,000 acre-ft ONDJFMAMJJASONDJFMAMJJAS o I CO DC O CC Ul CO LU EC 160 120- 40 - Colorado River storage project, Colorado-Utah (IFPR) Maximum capacity 31,620,000 acre-ft ONDJ FMAMJ JASONDJFMAMJ JAS 120 - Shasta Lake, California (FIPR) Maximum capacity 4,377,000 acre-ft l ! ONDJ FMAMJ JASONDJFMAMJJAS 1983 1984 120 - New York City reservoir system. New York (MW) Maximum capacity 1,680,000 acre-ft ONDJFMAMJJASONDJFMAMJJAS 120 80- 40- Mississippi River headwater system, Minnesota (FMR) Maximum capacity 1,640,000 acre-ft QNDJFMAMJJASONDJFMAMJJAS 120- 80- 40- Lake Oahe, South Dakota (FIP) Maximum capacity 22,240,000 acre-ft Jj . X. ONOJ FMAMJ JASONDJ FMAMJ JAS 160 80 40- 8 Lake Texoma, Oklahoma-Texas (FMPRW) Maximum capacity 2,722,000 acre-ft '1 120- OND JFMAMJ JASONDJFMAMJ JA S Clark Hill Reservoir, South Carolina-Georgia (FP) Maximum capacity 1,730,000 acre-ft 80 1 ONDJFMAMJ JASONDJFMAMJJAS 1983 1984 Figure 4. Month-end storage of selected reservoirs in the United States for water years 1983 and 1984 compared with median of month-end storage for reference period 1961 to 1982. Principal reservoir and water uses: F, flood control; I, irrigation; M, municipal; P, power; R ( recreation; and W, industrial. (Source: Compiled by H. C. Tang from U.S. Geological Survey data.) 12 National Water Summary 1984 Hydrologic Conditions and Events by considering the annual flow of the Nation's three largest rivers the Mississippi, the St. Lawrence, and the Columbia. The combined average water year 1984 flow for these three rivers was more than 1.27 million cubic feet per second (ftVs), or 23 percent above the annual average. Moreover, the combined average flow of these rivers for each season in water year 1984 also exceeded its respective seasonal average. Additional evidence for the nearly nationwide pat- tern of abundant surface-water resources (in water year 1983 as well as 1984) can be obtained from a check of the monthly flow and storage content of selected rivers and reservoirs across the country (fig. 3). The graphs indicate that, in at least 8 months of water year 1984, the nine rivers had flows in excess of the 30-year median value. Moreover, the Missouri River at Hermann, Mo., and the St. Lawrence River near Massena, N.Y., had discharges in excess of median flows in all 12 months. Graphs of monthly reservoir storage across the country show a basically similar pattern (fig. 4). Seven of the nine selected reservoirs had storage content in excess of a 21-year median value in at least 7 months of 1984. Two reservoirs exceeded the median values in 11 months and two reservoirs exceeded median values in all 12 months of water year 1984. A tendency for most of the country to experience uniformly either excessive (as occurred in 1984) or deficient streamflow has been recognized for some time (Busby, 1963). The specific pattern of runoff in 1984 is the most common of several systematic and recurrent modes of nationwide streamflow variation (Lins, 1985). Moreover, the co-occurrence of opposing excessive and deficient flow departures in the middle Missouri River valley and in southern Texas also has been documented as a recurring pattern of variation on annual time scales (Lins, 1985). Thus, in a long-term context, the patterns characteristic of the 1984 water year are, in many ways, quite typical of annual streamflow variations in the United States. Directly contributing to these general patterns of nationwide runoff were a series of significant and diverse hydrologic events. The geographic locations of these events are shown in figure 5, and a listing appears in table 1. Although many of these hydrologic events resulted from ephemeral meteorological conditions, others followed from more persistent atmospheric con- ditions. The flooding that occurred in the Great Basin and Central Rockies, for example, was primarily the result of the melting of a record snowpack that began accumulating in the Rockies in November 1983 (table 1, event 64). Similarly, a series of frontal systems brought showers and thunderstorms throughout the month of June 1984 to much of the Central Great Plains. As a result, peak flows along several streams within this region were the highest observed over a 50- to 80-year period of record (table 1, event 69). As for the low streamflows that occurred in parts of Texas, some areas had experienced more than 52 consecutive weeks of drought by the end of water year 1984. Such examples of hydrologic extremes emphasize the importance of climatic persistence in determining large-scale annual variations in streamflow. Table 1. Chronology of significant hydrologic and water-related events, August 1983 to September 1984 [The events described below are representative examples of hydrologic and water-related events that occurred throughout water year 1984. However, to provide continuity with the 1983 National Water Summary, the chronology begins with the events of August 1983. Toxic spill data were provided by the U.S. Coast Guard National Response Center. Fishkill data were provided by the U.S. Environmental Protection Agency based on reports transmitted by State agencies. Meteorological data mostly are from reports of the National Oceanic and Atmospheric Administration (NOAA). Abbreviations used: mg/L = milligrams per liter, Mgal = million gallons, Mgal/d = million gallons per day, ft /s = cubic feet per second, mi = miles, mi = square miles, gal = gallons, in. = inches, bbl = barrels, mi/hr = miles per hour] Location number in figures Event August 1983 1 Runoff from as much as 12 in. of rain on August 2 caused sharp rises and moderate flooding in southern Louisiana on the Amite River and nearby streams. The flow of the Amite was the highest in 45 years of record for August. 2 About 25,000 fish in a 1-mi reach of the Saline River near Equality in southern Illinois were killed by strip-mine effluent (sulfuric acid) on August 3. The Saline River is a tributary of the Ohio River, entering 40 mi southeast of Evansville, Ind. 3 Heavy thunderstorms on August 10 moved northward across Las Vegas Valley and caused flash flooding and major damage to more than 100 homes in the area. The heaviest rain occurred west of the city where the eastward- sloping Flamingo and Las Vegas washes became swollen beyond capacity. 4 In mid-August, Hurricane Alicia became the first hurricane to make landfall in the conterminous United States in 3 years. According to NOAA, the hurricane was one of of the costliest in Texas history. Alicia caused widespread damage to a large part of southeast Texas, including areas near Galveston and the entire Houston area. Rainfall amounts in coastal areas were 6 to 8 in. 5 In the Pacific Ocean, drought conditions on American Samoa, which had prevailed since October 1982, contributed to a sharp increase in chloride concentration in water from public-supply wells; some wells were shut down when the chloride concentration reached a level of 600 to 1,000 mg/L. On August 15, as a result of reduced water supplies due to terminated pumping of the wells, two tuna canneries, which normally use 1 Mgal/d, ceased production. On Guam, although drought conditions ended in August, the U.S. Navy's Fena Valley Reservoir had the lowest water level since the dam was completed in 1950. National Water Summary 1984 Overview 1984 Water Year 13 AMERICAN SAMOA AND GUAM PUERTO U'S- VIRGIN RICO EXPLANATION Symbols indicate type of event. Numbers correspond to those in table 1. Boundary lines (solid and dashed) are used only to show areas of widespread flood event. For widespread droughts, inverted triangles indicate some of the areas affected. ISLANDS Pollution; fishkill; toxic spill Mudslide Drought; deficient streamflow; water shortage High ground-water levels (?) Flood; excessive runoff; __ high lake levels I w I Large area affected by flooding L§ij or excessive runoff (solid and dashed boundary lines help to differentiate areas that overlap) Figure 5. Location or extent of significant hydrologic and water-related events in the United States, Puerto Rico, U.S. Virgin Islands, Guam, and American Samoa, August 1983 to September 1984. Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figure 5 Event August 1983 Continued 6 In southern California, runoff from unusually heavy rains on August 17 and 18, associated with the breakup of Hurricane Ishmael, produced moderate, but widespread, flooding in south-coastal areas and the desert areas of Imperial and San Bernardino Counties. Many secondary roads were washed out. On August 18, the stream gage on the Amargosa River at Tecopa Hot Springs, about 50 mi southeast of Death Valley, experienced a peak discharge of 10,800 ft3/s; this was more than twice the previous all-time high flow in 23 years of record. 7 On August 23, a ruptured pipeline about 5 mi west of Lake Charles in southwestern Louisiana discharged more than 290,000 gal of crude oil into Bayou Verdine. 8 Drought conditions persisted in much of the Southeast and Midwest, although rains near the end of August relieved drought conditions in parts of the Southeast. Streamflows were the lowest of record for August in parts of Kansas and extreme southeast New Mexico. Some areas of west Texas received some relief from the severe drought during the latter part of the month from rains caused by Hurricane Alicia. Parts of north Texas received as much as 4 in. of rain. In Iowa, August was the driest and hottest on record. 14 National Water Summary 1984 Hydrologic Conditions and Events Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figures Event September 1983 9 On September 9, on the Ohio River near Wheeling, W. Va., about 1 '/2 million fish were killed along 8 mi of the river by a discharge of cyanide into the river from a metals plant. 10 On September 14, at Los Banos, Calif., 70 mi southeast of San Francisco, a ruptured pipeline flooded Panoche Creek and a 1-acre marsh with 200,000 gal of medium- weight oil. Panoche Creek is a tributary of the San Joaquin River. 11 On September 15 and 16, in southwestern Georgia, a spill of toxaphene killed about 35,000 fish (mainly game species) in a 1 Vi-ra\ reach of Muckaloochee Creek and in the 75-acre Wells Mill Pond near Smithville. The creek is a tributary of Flint River, which flows through Albany, Ga. 12 From September 16 to 18, near Effingham in southeastern South Carolina 70 mi east of Columbia, food-plant wastes discharging into the stream because of a lagoon-dike failure killed about 17,000 fish (70 percent game fish) in a 14-mi stretch of the Lynches River. 13 On September 17 and 18, in northern Illinois 55 mi west of Chicago, toxic materials from farming operations killed 46,000 fish along 4 1/2 mi of Little Indian Creek near Leland. The creek is a tributary of the Illinois River. 14 On September 23, in the Prescott area of central Arizona, extreme amounts of precipitation from thunder- storms caused large flash floods. Measured amounts of rainfall at eight unofficial sites for the 36-hour storm period were 11 to 14.9 in. The peak discharge along Willow Creek was among the greatest measured in Arizona for streams with drainage areas of nearly the same size. Damage to public and private property was estimated to total nearly $2 million. 15 Flash floods occurred in several parts of south Texas as a result of thunderstorm rainfall of 3 to 7 in. or more on September 18 and 19. Flooding was widespread in Bexar County; one person was killed. In the Harris County-Houston area, three people drowned during the widespread flooding. 16 On September 28 and 29, flash flooding occurred in southeastern Nebraska and adjacent Kansas as a result of rains of 3 to 6 in. and as much as 8 in. in some local areas. The recurrence interval was estimated to be about 10 years. Considerable lowland flooding occurred along the Little Blue and Republican Rivers and their tributaries. Damage was primarily to farmlands and to county roads and bridges. _____ September to October 1983 ____________ 17 Heavy rains, from September 28 to October 3, deluged the southeastern quarter of Arizona with 3 to 11 in. of precipitation. Much of the moisture was supplied by Tropical Storm Octava. The largest floods of this century or the largest known floods occurred in places along the Santa Cruz, San Pedro, San Francisco, and Gila Rivers. Extreme floods also occurred on a few of the streams that are tributary to the major rivers in the area. The recurrence interval of the flood was greater than 100 years for the major rivers and several of the larger tributaries. This was Arizona's seventh major flood in 6 years. Preliminary estimates of damage to homes, agriculture, businesses, and public property totalled more than $175 million. More than 1,300 homes were damaged severely or destroyed. At least 10 storm-related deaths were reported. Flood damages along the Gila and San Francisco Rivers in New Mexico were reportedly more than $14 million. Damage to bridges and roadways on the secondary, primary, and interstate highways was severe with several major highways closed during and following the flooding. The President declared this to be a major disaster area as a result of the flood damage. October 1983 18 After the smallest seasonal decline ever recorded 0.5 ft between June 30 and September 25 Great Salt Lake began an unusually early rise. By mid-October, the level had risen 0.3 ft to an altitude of 4,204.55 ft above sea level. 19 On October 17, at an oil refinery at Clear Creek, Tex., in the Houston-Galveston area, more than 100,000 gal of light crude oil leaked from a tank, and much of the spill entered Clear Creek. The spill adversely affected fish and wildlife in the area. Clear Creek is a tributary of Galveston Bay. Cleanup was completed by October 31. 20 From October 19 to 21, torrential rains generated by northeastward-moving remnants of Hurricane Tico caused flooding in large areas from west Texas through Oklahoma to southern Missouri. Rainfall of more than 10 in. was common in parts of southwestern and central Oklahoma. As much as 13.8 in. of rain in 4 days caused flooding in Oklahoma City and many small communities. Amounts in southern Missouri generally were 4 to 7 in. In Oklahoma, at least five deaths resulted from the storm, and damage estimates were about $18 million for property and $77 million for agriculture. The President designated 16 counties as disaster areas. Peak flows of some tributaries of the Red River were the highest in 30 to 50 years of record, and estimated recurrence intervals were 50 to 100 years or more. Although the storm caused flash flooding, massive flooding generally was prevented by flood-control reservoirs that had been depleted by a summer- long drought. Guthrie, Okla., about 30 mi north of Oklahoma City, was one of the towns most severely affected by flash flooding from heavy rains. Nearby Cottonwood Creek crested at nearly 10 ft above flood stage. National Water Summary 1984 Overview 1984 Water Year 15 Table 1. Chronology of significant hydrologic and water-related events Continued Location number Event in figures October 1983 Continued 21 The October rains brought long-term relief to the entire drought-stricken area of west Texas. As much as 4 in. fell on some counties where severe drought conditions had prevailed for many months. 22 On October 27, northwest of Lake Texoma in southern Oklahoma, a pipeline break leaked 42,000 gal of crude oil into the Washita River. High river waters prevented containment, and the oil was carried into the upper area of Lake Texoma. 23 The October 28 Borah Peak earthquake (magnitude 7.3 on the Richter scale), in Custer County, central Idaho, contributed to significant changes in flows of springs and to record-high surface runoff in the Big Lost River basin. The earthquake also is believed to have caused the erratic behavior of Old Faithful, a geyser in Yellowstone National Park 150 mi to the east, by altering ground-water flow patterns under the geyser. ____________________ _______ November 1983 ____________________ 24 On November 2 and 3, ice-jam floods occurred in the Tanana Valley of central Alaska as a result of the combination of sharply cooler temperatures in late October and of carryover of high streamflows. The ice jam of Salcha Slough, a tributary of the Tanana River about 33 mi east of Fairbanks, recurred on November 8. Wells and septic systems in the area were unusable for several days due to resultant high ground-water levels. 25 On November 4, heavy showers and thunderstorms caused local flooding in the Virgin Islands, especially over the eastern one-half of St. Croix, where 24-hour totals reached nearly 9.5 in. Major road damage occurred on St. Croix and St. John along with minor damages to some homes from overflowing creeks on parts of St. Croix. 26 On November 9, the Delaware River Basin Commission declared a drought warning for the Delaware River as a result of a dearth of rainfall in the reservoir storage areas (mainly in southeastern New York) of the Delaware, thereby putting restrictions and other conservation measures into effect. The Delaware River Master (a U.S. Geological Survey hydrologist designated in accordance with a U.S. Supreme Court decree) had advised interested parties on October 27 that restrictions on diversions of water from the basin by New York City were imminent. 27 On November 22 and 23, near Farmington in northwestern West Virginia, a tank truck spilled 4,000 gal of liquid sodium hydroxide into Little Dunkard Mill Run and killed 16,000 fish along a 2'/2-mi reach. The stream is a tributary of Buffalo Creek. 28 From November 24 to 27, local flooding was caused in many parts of Maine and Massachusetts by heavy rains and strong winds. Rainfall totals were commonly 2 to 4 in. in Maine, with as much as 5.4 in. at Bangor. About a dozen roads in Bangor alone were washed out or flooded to dangerous levels. More than 3 in. fell in much of eastern Massachusetts. Gale winds and high tides compounded the problems in coastal areas. 29 On November 27, in the Birmingham, Ala., area, a 24-hour rainfall of 5.2 in. triggered flash flooding of low areas. 30 On November 28 and 29, a combination of heavy rains and snowmelt caused by warm temperatures resulted in widespread flooding and mudslides in the southern Kenai Peninsula south of Anchorage, Alaska. The flood recurrence intervals may equal or exceed 100 years. 31 In late November, a ruptured pipeline near Barceloneta, Puerto Rico, spilled from 1 to 5 Mgal of mostly industrial wastes to the shallow ground-water bodies. ___ December 1983 ________ 32 On December 2 and 3, heavy rains over the northern one-half of Mississippi and Alabama, exceeding 9 in. at Birmingham, caused widespread flash floods. Peak flows of several streams were as high as those likely to occur once in 50 to 100 years. One person died in Alabama as a result of the flood, and at least 2,700 dwellings in the two States were damaged. In west-central and northeast Mississippi, serious river flooding occurred in the Yazoo, Big Black, and Tombigbee River basins including flooding of homes mainly near the cities of Greenwood, Grenada, and Columbus. Rapidly rising water levels along the upper Black Warrior River above Tuscaloosa resulted in disruption of barge movement; many barges sank, and one lodged in the spillway gates of a control structure. 33 On December 10 and 11, heavy rains of 5 to 8 in. occurred across southern Louisiana and caused widespread flash flooding. Also, Sabine Parish in northwestern Louisiana received heavy rains of 5 in. or more. In east Texas, as much as 10 in. of rain caused local flooding, especially in San Augustine County. 34 From December 12 to 15, flooding in eastern Pennsylvania along such major rivers as the Susquehanna, Delaware, Lehigh, and Schuylkill was caused by 2.5 to 5.5 in. of rain. Some of the most extensive property damage occurred in Tioga and Bradford Counties. Two drownings were reported. 35, 36 On December 19, a drought emergency was declared for the Puna, Kau, and south Kona areas on the island of Hawaii. On December 25 and 26, heavy thunderstorm rains of 6 to 10 in. over Maui and northern parts of the adjacent island of Hawaii produced localized flash flooding that caused some damage to crops, roads, and construction projects. Despite the destructiveness, the rains brought temporary relief from the year-long drought. Nevertheless, 1983 was the driest year of record in many areas. 16 National Water Summary 1984 Hydrologic Conditions and Events Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figure 5 Event December 1983 Continued 37 On December 24, a ruptured storage tank in the Baltimore, Md., area leaked 3,365 tons of sulfuric acid, of which about 90 percent entered the Cabin Branch of the Patapsco River. Cleanup included spreading soda ash to neutralize the acid in the soil and water. 38 On December 24, in Sea Rim State Park near Port Arthur, Tex., adjacent to the Louisiana border, 84,000 gal of crude oil discharged from an oil well because of failure to close the wellhead valve. Part of the oil flowed into Lost Lake and adjacent marshland before being recovered; the oil reportedly killed some birds in the State park. 39 The cold wave that gripped the midcontinent area of the country caused record cold for the month in Louisiana. On December 16, northern Louisiana received 8 in. of snow, an unusual occurrence. The Red River at Shreveport froze over for the first time in recorded history. On December 27, Baton Rouge pumpage was reported within about 3 percent of absolute capacity, owing to frozen and broken water pipes causing loss of pressure. January 1984 40 Intense precipitation in the State of Washington on January 4 and 5 caused flooding in the foothills on the western side of the Cascade Mountains. The floods had a recurrence interval of about 25 years and caused significant channel changes in small drainage areas. 41 On January 9, nearly 30,000 gal of jet fuel was spilled into the Mississippi River near Bruins, Ark., 25 mi south of Memphis, Tenn., when a tanker barge struck a river dike and sank. No cleanup of the spilled material was feasible because of the swift river current. 42 On January 9, chemical effluent, possibly highly concentrated sodium hydroxide or one or more aromatic hydrocarbons, killed about 10,000 fish along 2.6 mi of the Left Fork of Falls Run near Falls Mill, Braxton County, in central West Virginia. Falls Run is a tributary of the Little Kanawha River. 43 On January 12, more than 6,000 fish were killed by ammonium nitrate fertilizer in Tarver Branch near Woodbury, Ga., 50 mi south of Atlanta. The contaminant reached the stream as a result of firefighting operations at a bulk fertilizer warehouse. Tarver Branch is a tributary of the Flint River. 44 Moderating temperatures and rainfall near the end of January in the Northwestern States on both sides of the Continental Divide triggered ice-jam floods along several streams. In Union County, northeastern Oregon, overflow from several rivers caused loss of livestock and extensive damage to State parks. In eastern and northern Idaho, ice-jam floods along the Salmon and St. Joe Rivers damaged parts of Salmon and Calder, respectively. In the Missouri River basin, an ice jam nearly 500 mi long formed in the Missouri River above Jefferson City, Mo. February 1984 45 Between February 11 and 16, various combinations of thawing temperatures, rainfall, and ice jams caused lowland flooding in many parts of the Nation. In western Oregon, rains of 4.5 in. in 24 hours on February 12 and 13 caused floods, mudslides, and rockslides. Rainfall also was especially heavy in north-central Virginia, western Maryland, and Pennsylvania. Flows and flooding along the Potomac River were the greatest since Tropical Storm Agnes in 1972, but damage did not approach the severity of that storm. Ice-jam flooding was common in Illinois, Indiana, and New York State. Lowland flooding also affected the lower reaches of the Platte and Elkhorn Rivers in Nebraska. 46 The flow in the Arkansas River reached the Garden City, Kans., gaging station for the first time since 1975 on February 15. Ground-water levels in the adjacent alluvium rose 17.4 ft in 3 days to a level of 10.1 ft below land surface. The flow was due to high moisture conditions and subsequent abnormal ground-water seepage into tributaries entering the river downstream from John Martin Reservoir in eastern Colorado. 47 On February 17, at an oil facility in El Segundo, Calif., near the southeastern edge of Los Angeles, a ruptured tank discharged 42,000 gal of caustic phenol. The pollutant soaked into the ground. 48 During February, widespread ground-water contamination by the pesticide ethylene dibromide was discovered in north-central Connecticut and south-central Massachusetts. This chemical was used as a soil fumigant on tobacco fields from the mid-1950's to 1983. __________________March 1984________________ 49 During the period from March 6 to 10, moderate to severe flooding occurred in southern Georgia and parts of northern Florida, caused by runoff from heavy rains (as much as 9 in. in a 24-hour period) on March 5 and 6; totals of 5 to 6 in. were common. Floods on some Georgia streams had recurrence intervals of 50 years. The Suwannee River and its tributaries were reported to have experienced floods of 10- to 25-year recurrence intervals. The Withlacoochee River at Pinetta was within 1 ft of record high and nearly a 100-year-recur- rence flood. With the Suwannee River in flood and many miles of developed property under water, the Suwannee River Water Management District established a policy of eventual acquisition of all property in the Suwannee River flood plain. National Water Summary 1984 Overview 1984 Water Year 17 Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figures Event March 1984 Continued 50 Very light rain on March 13 and 14 over most of coastal southern California broke a 10-week drought. Santa Barbara had its driest January (0.21 in.) and February (0.12 in.) of record since 1868. The city of Los Angeles had the second driest January and February of record since 1878 (0.18 in.). At San Bernardino County Flood Control headquarters, January rainfall was only 0.18 in. and February rainfall was 0.19 in. 51 On March 19, near St. Helens, Oreg. (20 mi north of Portland), an oil tanker ran aground on the rocky bottom of the Columbia River, spilling more than 150,000 gal of heating oil into the river. 52 A severe storm system from March 27 to 30, combining high winds, snow, ice, and thunderstorm rains, battered many parts of the Eastern United States. At least 80 deaths were attributed to the storm. Damage was greatest from tornadoes in the Southeast and from high winds, tides, and associated flooding along coastal areas from Massachusetts to the Carolinas. Moderate flooding occurred along many streams in the Carolinas and in southeastern Virginia. ____________________________April 1984_______________________________ 53 On April 4 and 5, in northern New Jersey and southeastern New York, severe flooding resulted from intense rains, about 5 in. within 24 hours in some places, falling on frozen ground combined with melting of a residual snowpack. Two deaths were reported. Peak flows on the Wanaque and Ramapo Rivers were the highest in 68 and 66 years of record, respectively. In northern New Jersey, more than 9,000 people were forced to flee from their homes because of rising water. 54 On April 6, at Groton, Conn., a transformer leaked 30 gal of polychlorinated biphenyl (PCB), of which 10 gal entered the Thames River. The remainder, spilled on shore, was cleaned up within a few days. 55 A series of rains between April 9 and 15 caused moderate flooding in northern Florida. Peak discharge on the Suwannee River at Branford on April 13 and 14 had a recurrence interval of about 25 years. 56 Water samples taken in mid-April showed that the Des Moines, Iowa, water supply contained nitrate in excess of Federal recommended limits for drinking water. Des Moines obtains its water from infiltration galleries located adjacent to the Raccoon River. Low levels of trichloroethylene (TCE) also had been detected in Des Moines water samples. 57 On April 16, the Honolulu Board of Water Supply asked residents on Oahu to reduce usage of water by 10 percent because of a drop to "caution" water levels at five major sources. Three danger signals, "caution," "alert," and "critical," are used. 58 On April 24 and 25, in southeastern Iowa near Fairfield, nearly 20,000 fish were killed by ammonia (from fertilizers) in Crow Creek. 59 On April 29, near Hopewell, south of Richmond, Va., 650 gal of sulfuric acid was spilled into the James River from a defective heat exchanger at a chemical plant. The pH (hydrogen ion concentration) of the river water had returned to normal by May 2. 60 Samples of ground water withdrawn from a test well at a hazardous waste landfill near Furley, Kans., north of Wichita, contained more than 213,000 mg/L of organic compounds. Although specific chemicals were not identified, the organic compounds were determined to be solvents. The landfill has been closed since January 1982 when investigation revealed that hazardous chemicals had contaminated ground water beneath the site and were present in nearby Prairie Creek. The high concentration of organic solvents observed in April 1984 was almost 10 times greater than concentrations observed in January 1982 when the landfill was closed. ____________________________May 1984_______________________________ 61 On May 2, in northwestern Indiana, drainage from an area spray-irrigated with swine waste, killed about 21,000 fish along 3.8 mi of Bridge Creek near Delphi. The creek flows into Deer Creek, a tributary of the Wabash River, 60 mi northwest of Indianapolis. 62 During the first 8 days of May, a series of storms moved eastward from northeast Texas to New Jersey, producing heavy downpours and flooding in many eastern and east- central parts of the United States. In central and southern Kentucky, for example, runoff from 4 to 8 in. of rain between May 5 and 7 caused most streams to reach flood stage; flows in Little River, Bacon Creek, and Russell Creek near Columbia, 60 mi southwest of Lexington, exceeded the 100-year flood. Widespread flooding occurred in the Big Sandy, the upper Kentucky, the Cumberland, and the Green River basins. In southwestern Virginia, extensive flooding occurred in Dickenson, Buchanan, and Washington Counties on May 7. In Tennessee, floods resulting from 4 to 9 in. of rainfall from May 5 to 8 had recurrence intervals ranging up to at least 50 years. Three deaths were reported. In southwestern West Virginia, the peak discharge of Tug Fork at Kermit on May 8 was equal to a 40-year-frequency flood; one death was reported, and thousands of people were evacuated because of rising water. 63 On May 10, during and following explosions and a fire at a manufacturing plant in Peabody in northeastern Massachusetts, 5 Mgal of runoff from firefighting at the plant entered the North River, which flows into Salem Harbor. The firefighting runoff contained low levels of cyanide, toluene, and benzene from 1,000 bbl of chemicals normally available for plant operations. 18 National Water Summary 1984 Hydrologic Conditions and Events Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figures Event May 1984 Continued 64 Warming temperatures in the Rockies, beginning about May 11, increased snowmelt from a record snowpack and caused severe flooding in addition to accompanying mudflows and mudslides. Extensive flooding and sustained high flows occurred in the Colorado River basin, the Snake River basin, the upper North Platte River basin, and also in the Great Basin. Peak discharges on many streams exceeded the 100-year-recur- rence flood and, in many instances, were greater than the floods of the previous June. The flow of the Colorado River at the Colorado-Utah State line on May 27, 1984, for example, was the highest of the period of record since 1951. The Gunnison River in Colorado peaked on May 25, and peak discharges occurred again on June 7 and 8 as a result of rains in the North Fork of the Gunnison. On May 16 in Montana, a combination of heavy rains and melting snow caused flow of the Ruby River upstream of the Ruby River Reservoir near Alder to peak at 3,500 ft /s. This was 2.2 times the 100-year flood for the Ruby River at this site. In southern Wyoming, the flow of the Little Snake River near Dixon peaked at 12,000 ft3/s, a rate which had a recurrence interval of greater than 100 years. This peak discharge included flow from Grieve Reservoir which the flood had breached. On May 15, 6 miles downstream, flooding started in the town of Baggs, which was inundated by as much as 4 ft of water on May 16. The town remained under water for several days as the result of continued snowmelt runoff. Flow in the upper North Platte River in Colorado and Wyoming remained high during this period and for much of the spring. Near-record discharge was recorded on the North Platte River near Northgate, Colo., on May 17, and a tributary stream, Pass Creek near Elk Mountain, Wyo., had a peak flow of 4,660 ftVs on May 12. This flow exceeded the 100-year flood and was four times the previously recorded maximum. The heat wave speeded the melting of Utah's record mountain snowpack on May 13 and triggered floods and mudslides that killed one person and injured at least three. Snowmelt from a record snowpack in northeastern Nevada led to extensive flooding along the Humboldt River from April to June. The peak flow of the Humboldt at Palisade, Nev., on May 18 had a recurrence interval of about 50 years. _____ May to June 1984 ____________ 65 Heavy showers on May 26 and 27 covered the eastern part of the Plains States and many of the Eastern States. By the end of the month, these storms and others caused widespread floods. Flooding, from as much as 13 in. of rain in less than 24 hours, was especially severe in the Tulsa, Okla., area, where damages were estimated to be $150 million and 14 lives were lost. Most of the widespread damage was in the eastern part of the city along Mingo Creek where homes and business properties are concentrated. 66 During May, severe drought conditions continued to affect most of Puerto Rico, where the 6-month drought resulted in water rationing in San Juan and 35 other towns. Precipitation over the north coast was the least in 70 years. 67 Heavy rains and flooding in New England continued from May into the beginning of June, producing flows on many streams that were the highest since the disastrous floods of 1955. About June 1, peak flows of some rivers in Maine were the highest for June in 60 years of record. In northern Vermont, damage estimates exceeded $1 million in Washington, Lamoille, and Franklin Counties. Peak flow of Lamoille River at Johnson on June 7 nearly equaled the peak flow of record in 56 years at that measurement site and well in excess of 100-year-recurrence interval. The peak flow of the Connecticut River at Montague City, Mass., 10 mi south of the Massachusetts-Vermont State line, was the fifth highest for 80 years of record. In Connecticut, the peak flow of the Connecticut River at Hartford on June 1 was the fourth highest flow in 79 years of record. (See article "Record Late Spring Floods of 1984 in New England.") 68 Lowland flooding occurred for the second consecutive year along the North Platte River in western Nebraska in late May and early June as a result of runoff from the snowpack in Wyoming and the need to release water from Wyoming reservoirs. Peak discharges of the North Platte River at gaging stations upstream from Lake McConaughy were greater than the peak flows of water year 1983 and had recurrence intervals of about 25 years. Because peak flow of the South Platte River was only about one-half of the 1983 peak discharge, extreme flooding did not occur on the Platte River below the confluence of the North and South Platte Rivers as it did in 1983. The 1984 peak discharges of the Platte River in central Nebraska had recurrence intervals of about 15 years. 69 Repeated and heavy rains during June caused severe flooding in the Central Plains, especially in eastern Nebraska and adjacent areas of southeastern South Dakota, south western Minnesota, southwestern Iowa, northwestern Missouri, and northeastern Kansas. Parts of South Dakota received more than 5.5 in. of rainfall, and rains of more than 4 in. caused extensive damage in parts of Iowa and Kansas. Flood damage to property and crops in Iowa was estimated to be $1 billion, and storm and flood damage in 44 counties in Nebraska was estimated to be $94 million. In Minnesota, these storms caused the worst soil and crop losses of recent years. Peak flows on many streams in the six-State area were highest of record for June. Extensive flooding occurred along the Missouri, the Big Sioux, and the Nishnabotna Rivers. The flows on a few streams were all-time highs for the past 50 to 80 years. In eastern Nebraska, for example, the peak discharges of the Little Blue River near Fairbury on June 13 and the Big Blue River at Beatrice on June 14 National Water Summary 1984 Overview 1984 Water Year 19 Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figures Event May to June 1984 Continued were the highest flows in 63 and 82 years of record, respectively. Turkey Creek, a tributary of the Big Blue River in eastern Nebraska, had a peak discharge on June 13 of about 4 Vitimes the previous maximum in 24 years of record. The flood discharge was about three times the discharge for the 100-year recurrence interval. More than 600 residents of DeWitt, at the mouth of Turkey Creek, were evacuated. In southeastern South Dakota on June 23, the peak discharge of the James River near Scotland was at an all-time high in the 56 years of record and exceeded flows of the 100-year recurrence interval. (See article "June 1984 Floods on the Missouri River and Tributaries.") The greatest monthly volume of flow ever recorded in June during the past 50 to 75 years occurred on several streams in Minnesota, including the Minnesota, the Chippewa, and the Des Moines Rivers. Heavy flows of the Chippewa and Lac qui Parle Rivers into Lac qui Parle caused the Minnesota River (which flows through the lake) to flow upstream over the Marsh Lake Dam (the next dam upstream) as well as downstream out of the lake for several days during June. ______ June 1984 ___________ 70 On June 4, at Richmond, Va., 20 Mgal of sewage, which was discharged directly into the James River, by- passed the water-treatment plant. This was done to prevent possible plant damage from potentially dangerous and explosive chemicals in the runoff from a nine-alarm fire that destroyed a feed and seed warehouse. 71 Intense thunderstorms occurred over the southeastern tip of Minnesota and adjacent west-central Wisconsin on June 16. Seven inches of rain in 75 minutes was reported near Westby, Wis., 80 mi northwest of Madison. A flood with a recurrence interval greater than 100 years occurred on Spring Coulee Creek near Coon Valley, 5 mi northwest of Westby. 72 On June 25, water levels in the San Antonio area, Texas, "sole-source" Edwards aquifer declined to 625 ft above sea level and triggered Phase I, Voluntary Conservation, of the recently established water-conserva- tion plan. 73 Two fishkills occurred in June along Trout Creek in northeastern Florida, about 25 miles south of Jackson- ville, apparently caused by discharges from food-processing operations. Estimates of fish killed on June 15 were 80,000, and, on June 28 and 29, nearly 400,000 were killed. Trout Creek is a tributary of the St. Johns River. 74 In a 20-acre pond at Milan in southeastern Indiana, nearly 5,000 game fish died on June 29 and 30 from pollution by an insecticide. 75 In June, the level of Malheur Lake, Oreg., peaked at an altitude of 4,102.4 ft, highest in the 52-year period for which levels have been recorded or observed and exceeding the previous highest record level observed by 7 ft. Malheur and Harney Lakes, coalesced into a single body of water as a result of the rising water levels, covered nearly 150,000 acres. Eighteen ranch families were evacuated, and damages were estimated to be $13 million. Persistent flooding of lakeshore areas has been escalating since 1982. 76 In Puerto Rico, June rains, especially during the second one-half of the month, replenished the water resources of the island and thus ended a prolonged period of drought and water shortages. 77 In June in Frederick County in northwestern Virginia, a tire fire that had burned for 8 months following ignition on October 31, 1983, finally was quenched. The fire consumed a 4.5-acre mountain of 9 million used tires. At its peak, the fire generated more than 100,000 gal of residual oil per day. More than $1.25 million of Superfund money allocated by the U.S. Environmental Protection Agency assisted in the support of fire-suppression and pollution-control efforts. After containment of the surface contaminants, surface- water problems were minor, but long-range effects on ground water are uncertain. _______________________________July 1984_________________________________ 78 On July 1, the level of Great Salt Lake peaked at 4,209.25 ft above sea level, the highest level in more than a century. The historical high level, about 4,211.5 ft above sea level, was in 1873, when the lake covered about 2,500 mi2 . The lowest recorded level was 4,191.35 ft in 1963, when the lake covered only 1,000 mi2 . (See article "Rise of Great Salt Lake, Utah.") 79 The largest terminal lakes in west-central Nevada reached their maximum water levels in many years in July. Pyramid Lake, the terminus of the Truckee River, peaked at 3,813 ft above sea level, the highest level since the 1940's. Walker Lake, the terminus of the Walker River, peaked at nearly 3,972 ft above sea level, the highest level since the mid-1960's. Carson Sink, the normally nearly dry terminus of the Carson and Humboldt Rivers, reached a peak of about 3,876 ft above sea level, which probably was the highest since the 1860'sorthe 1870's. 80 On July 7, intense thunderstorms caused significant flooding of several streams in Westchester County, in southeastern New York State. As a result of this storm, the highest peak discharge since 1972 was recorded for the Bronx River. In north-central New Jersey, also on July 7, severe thunderstorms caused record or near-record flooding in the 190 mi2 drainage area of the North Branch Raritan River. At least 75 families 20 National Water Summary 1984 Hydrologic Conditions and Events Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figures Event July 1984 Continued were evacuated from their homes. Rainfall of 8.92 in. in 24 hours at Pottersville on the Lamington River was reported by the National Weather Service. Peak flows on the Lamington River and parts of the North Branch Raritan River were higher than any in the last 89 years. 81 Along a 7-mi reach of the Susquehanna River near Marietta and west of Lancaster in southeastern Pennsylvania, herbicides and pesticides from agricultural operations killed about 3,000 fish between July 11 and 15. 82 Hawaii entered the 18th month of a drought that began in January 1983. Irrigated sugar-cane fields on leeward slopes on Oahu, which have received only 50 percent of normal rainfall since 1983, were depending heavily on ground water for irrigation. Honolulu received 5.03 in. of rain in 1983, less than one-quarter of its normal annual amount of 22 in. In July 1984, Kalihi Stream near Honolulu had its lowest July flow in 70 years of record. On July 12, Oahu residents and businesses were ordered to reduce water usage by 10 to 25 percent. Kauai residents have been under water conservation orders since April 1983. 83 On July 16, in Juneau, southeastern Alaska, a mud and debris slide from an old drainage chute off Thunder Mountain caused extensive personal property damage. The slide followed 10 days of rain, of which 1.5 in. fell within the 24-hour period before the slide. 84 Denali (Mount McKinley) National Park, in south-central Alaska, was closed on July 26 after a third mudslide in 3 days blocked the only road in the park. The park received about 1.56 in. of rain in one 24-hour period and about 3.76 in. for the month. July rainfall in the park usually amounts to only a trace. 85 During the last 10 days of July, Nevada had many heavy thunderstorms that caused moderate to intense flooding. In the Moapa Valley and at Las Vegas, many flash floods caused damage in the millions of dollars and the deaths of at least two persons. 86 Heavy rains in the Northeast during July, especially July 15 to 21, resulted in widespread flooding. A washout on a rail line caused a passenger-train accident in northern Vermont. 87 Extremely dry conditions persisted in much of Oklahoma and Texas. Flows of many streams in central and south Texas were near or at record low flows for the month. 88 At the end of July, nearly all the streams in north-central and northeastern Montana had very low flows or dry channels. Milk River at Nashua and Teton River were dry, the first zero-flow occurrence in the period of record. In contrast, streamflow elsewhere in the State, was average or near average, except in the southwestern part of the State where flow was higher than average. ^^ _______ August 1984 89 Flash floods hit the Southwestern States on August 6 and 7. In New Mexico, six deaths and $2.5 million in property and roadway damage were reported. 90 From August 10 to 13, heavy rains caused local flooding on the eastern slopes of the Appalachians. Intense rains of 5 to 7 in. fell in a 3-hour period on August 13 on the headwaters of the Wills Creek basin in Somerset and Bedford Counties in southwestern Pennsylvania. Flooding occurred along a 28-mi reach of Wills Creek resulting in numerous evacuations and five deaths by drowning. The communities of Glencoe, Fairhope, and Hyndman suffered most of the devastation with total damage estimated in excess of $14 million. Peak discharge exceeded 100-year levels as far downstream as Hyndman. The flood was the highest observed at the Hyndman gage in the 34 years of record. In Maryland, peak discharge of a small stream west of Baltimore occurred on August 13 and had a recurrence interval of 75 years. In northwestern and west-central Virginia, intense local flooding occurred in parts of Loudoun and Nelson Counties; total rainfall from August 10 to 13, was as much as 6 in. in some locations. 91 About 4,400 fish died in a 1 '/2-mi reach of Bargers Run, which is a tributary of the Susquehanna River, near Liverpool, Pa., 20 mi north of Harrisburg, on August 17. The cause was runoff from a hog-manure lot. 92 In southeastern Colorado, heavy rains between August 18 and 22, resulted in high flows in Fountain Creek and the Arkansas River upstream from John Martin Reservoir. Considerable hail damage occured (August 21) in and east of Pueblo during the storms. Insurance claims resulting from the hailstorm and associated wind and flooding in southeastern Colorado totalled more than $20 million. 93 In central Idaho, an earthquake of magnitude 5.2 occurred in the morning of August 22, 8 mi east of Challis, in the same general area as the earthquake of October 28, 1983. The hydrologic responses of both earthquakes were rising water levels in wells and increases in streamflow. 94 Lightning in dry forest and prairie areas of northern and central Montana triggered massive forest fires beginning about August 25. The fires were fanned by 70-mi/hr winds, strong enough to help the blazes jump the Missouri River and fire lines. Areas primarily affected were sparsely populated federally owned timber and grasslands. More than 300,000 acres were burned. Potential flood and sediment problems in the burned areas are of concern. National Water Summary 1984 Overview 1984 Water Year 21 Table 1. Chronology of significant hydrologic and water-related events Continued Location number in figures Event September 1984 95 In southern Alaska, record-high August rainfall preceded by above-normal temperatures caused excessive runoff in the area of Portage Glacier, 60 mi southeast of Anchorage. Flooding of Portage Creek, near Portage Lake, was in the vicinity of the National Park Service's new observatory, which is under construction. 96 Intense rainfall of 4 to 6 in. in a 2- to 4-hour period on August 30, produced major flash floods in eastern West Virginia. Several streams near Marlinton and Webster Springs had peak flows with a recurrence interval of 100 years. The Cranberry River near Richwood, W. Va., reached a stage that was the highest recorded in over 40 years. 97 A continuing series of moderate to severe flash floods that extended from the end of July to September in the Las Vegas Valley, Nev., culminated in the drowning death of a five-member family when their vehicle was washed off a roadway on September 10. 98 Hurricane Diana, after stalling off the North Carolina coast on the night of September 11, moved inland near Southport, N.C., at about 1 a.m. on the 13th with heavy rains and winds of about 100 miles per hour. Winds quickly decreased to 80 miles per hour, and, by the afternoon, Diana was downgraded by the National Weather Service to a tropical storm. The system moved slowly westward over New Hanover, Brunswick, and Craven Counties in southeastern North Carolina and then moved northwestward. Early on September 14, the storm circled northeastward across the central Coastal Plain and moved out to sea. Significant flooding occurred along headwater and intermediate-sized streams (less than 1,000 mi ). Recurrence intervals of floods on smaller streams generally were 5 to 25 years. At Black River near Tomahawk, N.C., the highest flow of record (17,300-ft3/s) contributed to a flood with a recurrence interval of greater than 100 years. Although the storm produced excessive rains, dry antecedent conditions and the sandy nature of Coastal Plain soils contributed to minimize surface runoff, and flood crests were considerably below predicted levels. Total damage estimates were over $90 million including more than $20 million in structural and agricultural damage in Brunswick and New Hanover Counties. The coastal towns of Southport, Long Beach, and Yaupon Beach (Brunswick County), reported the greatest damage. As much as 16 in. of rain fell in parts of New Hanover and Brunswick Counties. Elsewhere in the storm's path, rainfall generally was 3 to 10 in. 99 Four inches of rain that fell in about 2 1/2 hours on September 23 resulted in flash flooding in Pine Bluff, Ark., southeast of Little Rock. Flood waters as deep as 6 ft on some city streets were reported. Sixty-nine buildings including residences, businesses, and public buildings were damaged, some seriously. 100 Hydrilla verticillata, the submersed aquatic plant from southeast Asia, that recently invaded the tidal Potomac River in the Washington, D.C., area, had become established on both sides of the river from Alexandria, Va., to Marshall Hall, Md., and also had been found in Chicamuxen Creek and Mallows Bay, south of Quantico, Va. Along most of the shoreline, Hydrilla was growing with many other submersed aquatic plants such as wildcelery, sago pondweed, coontail, and water-stargrass. It was most abundant from Hunting Creek to south of Dyke Marsh, the location where it was first discovered in 1982. The extremely rapid growth rate and reproductive capability of Hydrilla have made it a nuisance plant in California and Florida and in parts of the Southeastern United States. Although it has many of the same beneficial attributes as other submersed aquatic vegetation, concern is increasing that it may outcompete other, more desirable species and interfere with recreational use of the river. SELECTED REFERENCES Bergman, K. H., 1984, The climate of autumn 1983 Featur- ing the conclusion of a major El Niflo event: Monthly Weather Review, v. 112, p. 1441-1456. Busby, M. W., 1963, Yearly variations in runoff for the conterminous United States, 1931-60: U.S. Geological Survey Water-Supply Paper 1669-S, 49 p. Lins, H. F., 1985, Streamflow variability in the United States, 1931-78: Journal of Climate and Applied Meteorology, v. 24. [In press.] 22 National Water Summary 1984 Hydrologic Conditions and Events SEASONAL SUMMARIES OF HYDROLOGIC CONDITIONS, WATER YEAR 1984 By Harry F. Lins FALL SEASON OCTOBER TO DECEMBER 1983 Above-normal streamflow dominated most of the conterminous United States during the fall season of water year 1984 (fig. 6A). Above-normal streamflow occurred in a broad band across the Southwest, in Oklahoma and western Texas, and throughout the Mississippi Valley. Below-normal streamflow was con- fined primarily to the High Plains region and south- central Texas. This largely nationwide pattern of above-normal flows appeared in conjunction with below-mean 700-millibar (mb) [about 10,000 feet (ft)] pressure surface heights over the Eastern Pacific Ocean and the Western United States and above-mean 700-mb heights in the Western Atlantic Ocean (dashed lines, fig. 6E). The principal effects of the resultant atmospheric circulation pattern were below-normal temperatures over the central two-thirds of the country (fig. 6Q and above-normal precipitation across most of the Nation (fig- 6£>). Although large positive departures of streamflow from normal were distributed widely across the Nation between October and December 1983, the climatic conditions and events giving rise to these flows were diverse. The very high flows occurring in the Southern Plains and middle Mississippi and Ohio River valleys resulted mostly from a single storm that moved north- eastward across this region during a 7-day period in October. The storm, an extratropical cyclone, formed over Texas as warm moist air from the Gulf of Mexico mixed with the weakened remnants of the Pacific Hurri- cane Tico. Torrential rains, exceeding 10 inches (in.) in parts of Oklahoma, generated peak flows on some Red River tributaries in the 50- to 100-year-recurrence inter- val range. Cottonwood Creek, near Oklahoma City, crested at nearly 10 ft above flood level (table 1, event 20). In contrast, the high flows observed in much of California and Nevada resulted from numerous frontal storms trailing from low-pressure systems that moved ' EXPLANATION 400 Line shows points of equaf per- centage. Number shows percen- tage of normal seasonal streamflow. Values compared are the 1984 mean seasonal dis- charge and the normal seasonal discharge (1951-80) 6A Streamflow in the United States and Puerto Rico shown as a percentage of normal fall conditions Figure 6. Hydrologic conditions during the fall season, October to December 1983. (Sources: Compiled by H. F. Lins and H. C. Tang from National Oceanic and Atmospheric Administration, National Weather Service, meteorological data and U.S. Geological Survey streamflow data.) National Water Summary 1984 Seasonal Summaries 23 onshore between northern California and British Columbia during November and December. Similarly, above-mean flows along the east coast occurred in conjunction with the very regular movement of storms across the East and Southeastern United States during November and December. Local flooding was wide- spread in Maine and Massachusetts in late November after the fourth storm for the month swept through this region (table 1, event 28). Moreover, heavy rains in northern Mississippi and Alabama in early December produced severe flash flooding (table 1, event 32). Outside the conterminous United States, extreme conditions also were noted. In Alaska, for example, heavy rains and snowmelt resulting from warm temper- atures in late November led to widespread flooding and mudslides south of Anchorage on the lower Kenai Peninsula (table 1, event 30). On the island of Maui, in Hawaii, Christmas thunderstorms produced 6 to 10 in. of rainfall causing local floods while providing some relief from the drought that had persisted through the fall season (table 1, event 36). Temperature also affected streamflow during the fall season. The below-normal temperature that cov- ered much of the northern and central parts of the Nation during the fall season contributed to early and heavy snowfalls which kept the moisture from con- tributing immediately to streamflow. Nationally, tem- peratures during December were the coldest on record. 66. Mean height of 700-millibar pressure surface (solid lines in meters) over North America and departures from normal fall conditions (dashed lines in meters). 6C. Temperature in the conterminous United States expressed as a departure from normal fall conditions. ( A , above 70th percentile; B , below 30th percentile; N , between 70th and 30th percentiles). BD. Precipitation in the conterminous United States expressed as a percentile for fall conditions. The 50th percentile represents the median precipitation (A , above the 70th percentile; B , below the 30th percentile) Figure 6. Continued. 24 National Water Summary 1984 Hydrologic Conditions and Events WINTER SEASON JANUARY TO MARCH 1984 The national pattern of largely above-normal streamflow continued into the winter quarter (fig. 1A). The largest above-normal departures occurred in the upper Mississippi Valley and in southern Florida. High seasonal flows also were prevalent across the Great Basin and the western Rocky Mountains. The continuation of above-normal streamflow across much of the Nation came in association with a 700-mb flow pattern similar to but more intensified than that which existed during the fall (fig. IE). Princi- pal features of this upper air pattern included a deep trough over the North Pacific Ocean, a moderate ridge over the west coast of the United States and Canada, and a trough over the eastern two-thirds of the United States. Temperatures during the January-to-March period ranged from above normal along the Pacific coast and in the Northern Rockies and Northern Great Plains to below normal in the lower Great Lakes area, parts of the South, and sections of the Great Basin and the west-central Rockies (fig. 1C). Although severe cold engulfed the Nation in late December and persisted into January (the December-February period was the sixth coldest of record), the remainder of the winter quarter was quite mild over much of the country. February, in particular, was an unusually warm month from the Northern Great Plains to the Northeast. Precipitation varied from below normal along the Appalachians, in the Southwest, and along the Pacific coast to above normal along the southeast Atlantic coast and in the Central Great Plains and the Central Rocky Mountain regions (fig. ID). Notably, precipita- tion was below normal across much of the Nation during January but increased to normal amounts over most of the Nation during March. In general, the areas exhibiting excessive stream- flow during the winter quarter also experienced above- normal flows during each month of the period; namely, the Great Basin-Central Rockies region, the Northern Great Plains-upper Mississippi River valley area, west- ern Oklahoma-northern Texas, and Florida. Condi- tions giving rise to the flooding in each area varied considerably. The high flows in much of the upper Mississippi River valley resulted from snowmelt runoff and ice jams caused by the mild temperatures that began at the end of January and continued into March. In particular, moderating temperatures coupled with an ice jam nearly 500 miles long, which extended upstream along the Missouri River from Jefferson City, Mo., produced flooding along many streams near the end of EXPLANATION 400 Line shows points of equal per- centage. Number shows percen- tage of normal seasonal streamflow. Values compared are the 1984 mean seasonal dis- charge and the normal seasonal discharge (1951-80) 7A. Streamflow in the United States and Puerto Rico shown as a percentage of normal winter conditions Figure 7. Hydrologic conditions during the winter season, January to March 1984. (Sources: Compiled by H. F. Lins and H. C. Tang from National Oceanic and Atmospheric Administration, National Weather Service, meteorological data and U.S. Geological Survey streamflow data.) National Water Summary 1984 Seasonal Summaries 25 January (table 1, event 44). Similar conditions during the middle of February spawned lowland flooding in Illinois, Indiana, New York, Pennsylvania, Maryland, and Virginia (table 1, event 45). Moderate to severe flooding caused by 2 days of heavy rains affected southern Georgia and northern Florida. Flows on some Georgia streams had recurrence intervals of once in 50 years (table 1, event 49). High flows in the Great Basin-Western Rockies region, however, were associat- ed primarily with storm-generated runoff and, toward the end of the quarter, with snowmelt. C 7B. Mean height of 700-millibar pressure surface (solid lines in meters) over North America and departures from normal winter conditions (dashed lines in meters). 7C. Temperature in the conterminous United States expressed as a departure from normal winter conditions. ( A , above 70th percentile; B , below 30th percentile; N , between 70th and 30th percent!les). ID. Precipitation in the conterminous United States expressed as a percentile for winter conditions. The 50th percentile represents the median precipitation ( A, above the 70th percentile; B , below the 30th percentile) Figure 7. Continued. 26 National Water Summary 1984 Hydrologic Conditions and Events SPRING SEASON APRILTO JUNE 1984 Nationwide, the pattern of above-normal stream- flows persisted through the April to June period (fig. SA). Spring patterns were similar to those of the winter, with high-flows occurring in the Great Basin and the Northern Great Plains, but they increased in both areal extent and magnitude. For example, the combined average flow of the Mississippi, the St. Lawrence, and the Columbia Rivers during the spring months increased 68 percent compared to the winter season. As during the winter, the areas with the greatest departures from long-term normal conditions were in the Great Basin- Central Rockies, Northern High Plains-middle Missis- sippi River valley, and southeast Atlantic coast. Again, as in the winter, streams in these areas had above- normal flows in each month of the season. The only large area of significantly below-normal streamflows was in Texas. During the spring period, several notable events occurred. In northern New Jersey and southeastern New York, for example, severe flooding on April 4 and 5 resulted from intense rains falling on frozen ground and from melting of a residual snowpack. Peak flows of the Wanaque and Ramapo Rivers were the highest in nearly 70 years (table 1, event 53). Later, in early May, a series of storms moved eastward from northeast Texas to New Jersey and produced heavy downpours and flooding in many eastern and east-central parts of the United States. Extensive flooding between May 5 and 8 was reported along streams in central and southern Kentucky, southwestern Virginia, and Tennessee (table 1, event 62). In the Western United States, warming temperatures in the Rockies, beginning in mid-May, increased snowmelt from the record-high snowpack and caused severe flooding in addition to accompanying mudflows and mudslides. Extreme flooding occurred in the Colorado River basin, the Snake River basin, and also in the Great Basin. Peak discharges on many streams exceeded the 100-year flood (table 1, event 64). Finally, in June, rains replenished the water resources of Puerto Rico, ending a prolonged period of drought and water shortages (table 1, event 76). Associated with these elevated flows nationwide was a greatly reduced gradient in the 700-mb height field over North America (fig. 8fi). Such a reduction is typical in spring as the contrast in temperatures between high and low latitudes decreases. Specific aspects of the upper-air pressure field included intensification and northward extension of the North Pacific subtropical EXPLANATION 400 Line shows points of equal per- centage. Number shows percen- tage of normal seasonal streamflow. Values compared are the 1984 mean seasonal dis- charge and the normal seasonal discharge (1951-80) PUERTO RICO 75 8A Streamflow in the United States and Puerto Rico shown as a percentage of normal spring conditions Figure 8. Hydrologic conditions during the spring season, April to June 1984. (Sources: Compiled by H. F. Lins and H. C. Tang from National Oceanic and Atmospheric Administration, National Weather Service, meteorological data and U.S. Geological Survey streamflow data.) National Water Summary 1984 Seasonal Summaries 27 C. high-pressure area, a trough over the southern Pacific coast of the United States, and a relatively weak wester- ly upper-air flow over most of the conterminous United States. Climatologically, these patterns were associated with above-normal temperatures in the Pacific South- west, across the Northern Great Plains to the Great Lakes, and in Maine (fig. 8C). Below-mean tempera- tures dominated the Columbia Plateau-northern Rocky Mountain region, the middle Missouri and lower Missis- sippi River valleys, and most of the Southeast. Spring precipitation was normal to above normal over most of the Nation (fig. &D). The notable dry areas (the North- ern and Southern Great Plains, the central Great Lakes, and central California) generally were coincident with the areas of below-normal streamflow (fig. &4). Much of the very high streamflow that occurred in the North- ern and Central Great Plains came during June when, early in that month, an unusually cold air mass moved over the Rockies and the Northern Great Plains and generated severe weather and torrential rain over much of the region. Monthly mean flows were highest of record for June in parts of Iowa, Kansas, Nebraska, and South Dakota. In addition, peak flows on several streams in Kansas, Nebraska, and South Dakota were also highest of record (table 1, event 69). 8B. Mean height of 700-millibar pressure surface (solid lines in meters) over North America and departures from normal spring conditions (dashed lines in meters). 8C. Temperature in the conterminous United States expressed as a departure from normal spring conditions. ( A , above 70th percentile; B , below 30th percentile; N , between 70th and 30th percentiles). 8D. Precipitation in the conterminous United States expressed as a percentile for spring conditions. The 50th percentile represents the median precipitation ( A, above the 70th percentile; B , below the 30th percentile) Figure 8. Continued. 28 National Water Summary 1984 Hydrologic Conditions and Events SUMMER SEASON JULYTO SEPTEMBER 1984 Streamflow patterns changed little during the summer season from those observed during the spring (fig. 9A). The core areas of above-average flows in the Great Basin-Central Rockies, Northern Great Plains, and across much of the Atlantic coast persisted, although some variations in their intensity and extent were observed. For example, large areas of above-average rainfall were observed in the West and, more locally, along the east coast during the July to September period. Across the Great Plains, however, the area of exces- sive flows in the northern and central sections of the Plains decreased considerably as very low streamflows carried over from the spring in the southern sections and spread northward into the central sections. Another indication of the elevated state of summer season streamflows nationwide is evident in the combined average flow of the three largest rivers in the conterminous United States. Between July and September the Mississippi, the St. Lawrence, and the Columbia Rivers had a combined average monthly flow of 926,000 ft3/s. Although this value represents a 52-percent decrease from the spring flow (a seasonal decline in flows during summer being normal), it was still 14 percent above the average summer combined flow for these rivers. Specific events during the summer months included some record-setting flows. In July, for example, a slow-moving cold front moving eastward from the Northern Great Plains dropped locally heavy amounts of precipitation and produced record flooding on several streams in Connecticut and New Jersey. Several weeks later, a very similar frontal system produced rains which generated record flows on streams in Maine, Rhode Island, and New York (table 1, event 86). Perhaps the most notable streamflow event of the sum- mer quarter occurred during the middle of September in North Carolina. There, in response to several days of heavy rains associated with Hurricane Diana, severe flooding oc- curred on streams in the State's southeastern coastal plain region (table 1, event 98). Peak discharges on headwater streams had recurrence intervals in the 5- to 100-year range although only minor flooding occurred in the lowlands along the lower reaches of such major rivers as the Cape Fear and the Neuse. Porous, sandy soils coupled with locally dry antecedent conditions accounted for reduced flooding in the lowlands. The broad similarity in streamflow anomalies between the spring and summer seasons can be associated with a notable persistence in the pattern of upper air circulation (fig. 9B). The maps of spring and summer mean 700-mb pressure surfaces (figs. SB, 9B), do not show any apparent significant differences. Indeed, the only notable differences relate to the absolute height of the pressure contours and not to the EXPLANATION 400 Line shows points of equal per- centage. Number shows percen- tage of normal seasonal streamflow. Values compared are the 1984 mean seasonal dis- charge and the normal seasonal discharge (1951-80) 9A Streamflow in the United States and Puerto Rico shown as a percentage of normal summer conditions Figure 9. Hydrologic conditions during the summer season, July to September 1984. (Sources: Compiled by H. F. Lins and H. C. Tang from National Oceanic and Atmospheric Administration, National Weather Service, meteorological data and U.S. Geological Survey streamflow data.) National Water Summary 1984 Seasonal Summaries 29 C distribution or location of high- and low-pressure areas. The increase in the height of the contours across the map is associated with a "thickening" of the atmosphere that occurs every summer. This thickening, or expansion, of the atmos- phere occurs in response to the warmer temperatures of the summer season. The most obvious associations between the summer 700-mb circulation and surface streamflow patterns occur in the Western and Central United States. The con- tinued elevated flows in the Great Basin and Central Rockies resulted from the trough over coastal California, which deep- ened during the summer. Moreover, the intensification and expansion of the drought in the Southern and Central Great Plains was primarily caused by the westward and northward expansion of the "Bermuda High" into that region (note position of the 3,180-meter height contour over Texas and the Southeast in fig. 9B). With the position of this high-pressure area extending so far westward, moist tropical air from the Gulf of Mexico was not able to move northward into the Great Plains. Instead, the Gulf air moved into Mexico and, after taking on dry continental characteristics there, moved northward into the Great Plains. Temperatures and precipitation nationwide varied con- siderably during the summer quarter (figs. 9C, 9D). Through- out California and in much of Nevada, Utah, and the North- ern Rockies, temperatures averaged above normal. Across much of the Southwest, above-average precipitation resulted from the upper-air trough above the California coast. In north-central and northeastern Montana, high temperatures coupled with reduced rainfall led to exceedingly low flows in, or to the drying-up of, many streams (table 1, event 88). In contrast, much of the northwest and central portions of the Nation experienced normal summer temperatures. Given the below-average precipitation over much of the Pacific Northwest and most of the Central and Southern Plains, these normal temperatures helped to keep the reduced summer streamflows from being even lower. This was espe- cially true in north and west Texas where below-average temperatures prevailed. Finally, most of the eastern and southeastern parts of the country had normal or below- normal temperatures during the summer. Interestingly, de- spite the heavy rains along the southeast Atlantic coasts which accompanied Hurricane Diana, most of this region still re- mained below average in precipitation for the summer quarter. SB. Mean height of 700-millibar pressure surface (solid lines in meters) over North America and departures from normal summer conditions (dashed lines in meters). 9C. Temperature in the conterminous United States expressed as a departure from normal summer conditions. ( A , above 70th percentile; B , below 30th percentile; N , between 70th and 30th percentiles). 9D. Precipitation in the conterminous United States expressed as a percentile for summer conditions. The 50th percentile represents the median precipitation ( A, above the 70th percentile; B , below the 30th percentile) Figure 9. Continued 30 National Water Summary 1984 Hydrologic Conditions and Events Selected Hydrologic Events, Water Year 1984 Rising Lake Levels During the late 1970's and early 1980's, rising lake levels in the Central and Western United States created a host of flood problems affecting communities, highways, wetlands, recreational facilities, and agricultural lands adjacent to terminal or closed lakes. These lakes occur in interior drainage basins that have no natural outlet to the oceans. Runoff within these basins creates the lakes found in the low-lying areas of these drainage systems. The altitudes of such lakes fluctuate in response to changes in climate and (or) other changes in the hydrology of the interior-drainage system. Interior-drainage basins comprise 5 percent of the drainage area in North America (de Martonne, 1927). Within the past 2 years, high lake levels have caused flooding problems at the Great Salt Lake in Utah, Devils Lake in North Dakota, Big Marine Lake in Minnesota, Round and East Eightmile Lakes in Wisconsin, and the Malheur- Harney Lakes system in Oregon. In July 1984, the largest terminal lakes in west-central Nevada Pyramid Lake, Walker Lake, and Carson Sink reached their maximum water levels in many years (table 1, event 79). Because of the unusual nature of the rising lake-level phenomenon and the effects on neighboring communities, two of these lakes Great Salt Lake and Devils Lake are discussed in detail in this section. Saltair, a huge dance and recreational pavillion, being submerged by the Great Salt Lake, Utah. Water covered the dance floor to a depth of more than 1 foot on April 11,1984, as the lake level reached 4,207.7 feet. The lake peaked at 4,209.25 feet on July 1, 1984. (Photograph by Ted Arnow.) RISE OF GREAT SALT LAKE, UTAH National Water Summary 1984 Selected Events 31 By Ted Arnow The Great Salt Lake (fig. 10) rose 5.0 feet (ft) from September 25, 1983, to July 1, 1984, the second largest seasonal rise for this lake since records began in 1847. The maximum seasonal rise was observed the previous year when the lake rose 5.1 ft from September 18, 1982, to June 30, 1983. The lake declined only 0.5 ft during the summer of 1983; therefore, the net rise from Sep- tember 18, 1982, to July 1, 1984, was 9.6 ft. By comparison, the previously recorded maximum net rise during a 2-year period was 4.75 ft during 1970 and 1972. Great Salt Lake is the modern remnant of a much larger water body, Lake Bonneville, which covered about 20,000 square miles (mi2) in Utah, Nevada, and Idaho during the most recent ice age of the Pleistocene Epoch. Lake Bonneville reached its maximum level, approximately 1,000 ft above the present surface of Great Salt Lake, about 16,000 to 17,000 years ago. About 11,000 years ago, the lake declined to its current level of approximately 4,200 ft above sea level (Scott and others, 1982, p. 3). The lake level has a yearly cycle (fig. 11). It begins to decline in the spring or summer when the weather is hot enough so that the loss of water by evaporation from the lake surface is greater than the combined inflow from surface streams, ground water, and precipi- tation directly on the lake. It begins to rise in the autumn when the temperature decreases and the loss of water by evaporation is exceeded by the inflow. Ac- cording to past records, the rise can begin at any time between September and December and the decline any time between March and July. Thus, the level and volume of the lake reflect a dynamic equilibrium between the inflow and evapora- tion. The surface area and brine concentration are the major aspects of the lake that affect the volume of evaporation. During dry years, the water level declines, causing a decrease in surface area; consequently, the volume of evaporation decreases. Moreover, as the lake level declines, the brine generally becomes more concen- trated, which also decreases the rate of evaporation. During wet years, the water level rises, causing an increase of surface area; consequently, the volume of evaporation increases. As the lake rises, the brine generally becomes less concentrated, which also in- creases the rate of evaporation. When the lake level peaked on July 1, 1984, it was at an altitude of 4,209.25 ft above sea level, and it covered an area of about 2,300 mi2 . This level was still below the historic high level in 1873 at approximately 4,211.5 ft above sea level. At that time, the lake surface covered about 2,500 mi2 . At the other extreme, the lowest lake level was recorded in 1963 at 4,191.35 ft, when the lake covered less than 1,000 mi2 . During the summer of 1983, precipitation was above average, and evaporation was relatively small because of greater-than-usual cloud cover. These con- ditions resulted in an unusually small decline of lake level during the summer. By September 25, when the seasonal rise began, the lake level had declined only 0.5 ft. The excessive precipition continued throughout the fall and culminated in the wettest December ever recorded at Salt Lake City. By New Year's Day, Salt Lake City had received 24.26 in. of precipitation during calendar year 1983, about 1.6 times the average. The cumulative precipitation from January to June 1984 also was above average. Much of the precipitation fell in the form of snow on the mountains in the drainage basin. The snowmelt began soon after May 1, at which time the snow cover ranged from about 1.2 to 1.5 times greater than the average amount for May 1 in the Bear River basin, about 1.5 times the average in the Weber River basin, and from about 1.3 to 1.8 times the average in the Jordan-Provo River basin (Whaley, 1984, p. 9-13). The lake rose steadily from October 1983 through June 1984, primarily in response to the surface inflow that resulted from the excessive precipitation. The precipitation at the Salt Lake City Airport was about 1.5 times greater than average for the 9-month period, and the resultant inflow from the three major surface tributaries of the lake during that period greatly exceed- ed their average flows for this 9-month period: the Bear River flow was 2.7 times greater (3.12 million acre-ft), the Weber River flow was 2.1 times greater (923,000 acre-ft), and the Jordan River flow was 5.2 times greater (1.23 million acre-ft). The flow in the Bear River during water year 1984 was the greatest measured during 95 years of record, and the flow during water year 1983 was the second greatest on record. Similar annual records were observed for the Weber and Jordan Rivers based on the past 35 years of measurement. Because of the shape of the lakebed, more water is needed to raise the level of the lake each additional foot as the water altitude increases. Thus, the 5.0-ft rise from September 25, 1983, to July 1, 1984, involved about 15 percent more water than did the 5.1-ft rise from Sep- tember 18, 1982, to June 30, 1983. When the lake peaked on July 1, 1984, the net increase in volume represented by the 9.6 ft rise since September 18, 1982, was about 12 million acre-ft, and the increase in area was about 600 mi2 (an increase of 35 percent). This increase in the lake's area resulted in extensive damage to roads, railroads, wildfowl-management areas, recreational facilities (fig. 12), and industrial installations that had been established on the exposed lakebed. The capital damage at these facilities as the lake rose the 9.6 ft was approximately $212 million (Utah Division of Water Resources, 1984, p. 3-41). The salinity of the brine in Great Salt Lake before 1959 varied inversely with the lake level (fig. 11). During 1869, for example, when the lake was within a few feet of its historic high level, the concentration of . Historic high level Average level Historic low level Figure 10. Landsat thematic mapper image of Great Salt Lake, Utah. The lake was imaged on June 25 and July 2, 1984, during two passes of the Landsat satellite. The southern part of the lake crested at 4,209.25 feet on July 1,1984. The level is within 0.1 foot of the peak as shown on the image. The satellite image is capable of delineating the shoreline more completely than ground surveying or aerial photographic methods. The southern and northern parts of the lake are separated by a causeway, producing great differences in water quality in the two halves of the lake and thus differences in the color of the water. dissolved minerals was 15 percent of the brine weight. During 1930, however, when the lake was about 10 ft lower, the mineral concentration was 21 percent. Between 1957 and 1959, the Southern Pacific Transportation Co. built a railroad causeway, which divided the lake and restricted the movement of the brine. The southern part of the lake receives more than 90 percent of the freshwater inflow, whereas the inflow to the northern part is nearly all brine that moves through the causeway from the southern part. Thus, National Water Summary 1984 Selected Events 33 4190 30 Figure 11. Changes of water level and dissolved-mineral concentrations of Great Salt Lake, Utah, 1847 to 1984. Since 1959, the northern and southern parts of the lake have differed in water level and mineralization, the data for which are shown in blue for the southern part and in red for the northern part. (Source: Compiled by Ted Arnow from U.S. Geological Survey and Utah Geological and Mineral Survey data.) the water in the southern part always is higher and fresher than the water in the northern part of the lake. From 1959 to 1982, the brine concentration north of the causeway remained relatively constant at or close to saturation regardless of changes in lake levels. The concentration decreased somewhat, however, during the large lake-level rises of 1983 and 1984. The brine south of the causeway was close to saturation during the historic low lake level in 1963. As the lake rose, the salinity of the brine south of the causeway continued to change inversely with the lake level, but the salinity was less than it would have been before the construction of the causeway. In 1977, for example, at a lake level of about 4,200 ft, the mineral concentration was approxi- mately 12 percent, whereas before 1957 at the same level, it would have been more than 20 percent. The maximum recorded difference in levels between the two parts of the lake was 3.7 ft on July 1, 1984, when the salinity in the northern part was about 23 percent, and in the southern part, only about 6 percent. At 6 percent, which is less than two times the salinity of ocean water, the famed flotation powers of Great Salt Lake are practically nonexistent. The Utah legislature in 1984 approved an action to breach the railroad causeway to help equalize the water levels between the northern and southern parts of the lake. A 300-ft wide opening was completed on August 3. This will reduce the differences in level and salinity between the two parts of the lake, but it will not eliminate completely the differences. Given the uncer- tainty about future lake levels and the effects of in- creased flooding if lake levels continue to rise, the behavior of Great Salt Lake will continue to be the subject of intensive interest and study. Figure 12. Entrance to Antelope Island Causeway, looking west, with the lake level at 4,209.15 feet on June 16, 1984. Note center line of the Causeway showing through the water. The causeway was completed in 1968 when the lake level was at 4,195 feet. (Photograph by Ted Arnow.) 34 National Water Summary 1984 Hydrologic Conditions and Events RISE OF DEVILS LAKE, NORTH DAKOTA By Gregg J. Wiche Another example of a lake with rising water levels is Devils Lake in northeastern North Dakota. The Devils Lake basin is a 3,900-square mile (mi2) closed basin in the drainage of the Red River of the North (fig. 13). About 3,130 mi2 of the closed basin drains into Devils Lake itself; the remaining 770 mi2 are tributary to East Devils and Stump Lakes, which lie to the east. The topographic relief and surficial landforms of the basin are of glacial origin, which accounts for the large number of shallow depressions and potholes through- out the basin. Many of these depressions are connected by poorly defined channels and swales. The rising levels of Devils Lake (fig. 14) pose a flood threat to the community of Devils Lake, a Nation- al Guard Camp, roads, and sewer and lagoon systems of several other communities. Rising ground-water levels probably caused by the rising lake levels also have flooded basements and septic systems in and near the Devils Lake basin boundary Subbasin boundary Figure 13. Drainage basin of Devils Lake, N. Dak. (Source: Compiled by G. J. Wiche from U.S. Geological Survey data.) 1453 1440 1435 Lake outlet altitude 1430 1425 1420 1415 1410 1405 1400 I EXPLANATION Infrequent measurements Periodic measurements 1860 1880 1900 1920 1940 1960 1980 2000 Figure 14. Water levels of Devils Lake, N. Dak., 1867 to 1983. The outlet of Devils Lake is 1,453 feet above sea level. (Source: Compiled by G. J. Wiche from U.S. Geological Survey data.) city of Devils Lake. However, not all impacts of rising lake levels have been adverse; the water quality of the lake has improved, which, in turn, has increased fishing and other water recreation on the lake. An additional source of interest in Devils Lake is the fact that it is included as part of the Garrison Diversion Unit, a congressionally authorized water-development project. The primary reason for including Devils Lake in the proposed project is to stabilize the lake's level. Water-surface altitudes of Devils Lake were record- ed, albeit somewhat sporadically, from 1867 to 1901, and these records have been authenticated by the U.S. Geological Survey. In 1901, the U.S. Geological Survey established a gage on Devils Lake. The maximum water-surface altitude of 1,438 ft above sea level for the period of record of Devils Lake occurred in 1867, when the lake had a surface area of about 140 mi2. From 1867, the water-surface altitude of Devils Lake fell almost continuously until 1940, when it reached a recorded low of 1,400.9 ft above sea level and was a shallow, brackish body of water covering 10.2 mi2 (North Dakota State Engineer, 1944). From 1940 to 1956, Devils Lake rose; from 1956 to 1968, it declined again; and, in 1983, it rose to a modern maximum altitude of 1,428.1 feet. Lake levels have remained fairly stable during 1983 and 1984, and the surface area of the lake has been about 84 mi2. Swenson and Colby (1955) reported a dissolved- solids concentration of 25,000 mg/L in Devils Lake in November 1948 when the water level was only 3 ft above National Water Summary 1984 Selected Events 35 the recorded low level of 1940. Water samples collected in May 1979 indicated that, when the lake was at one of its peaks, dissolved solids were less than 2,000 mg/L (U.S. Geological Survey, 1980). Knowledge of the fluctuations of Devils Lake before 1830 is based on studies by Aronow (1957) and Callender (1968). Aronow (1957) developed a post- glacial chronology of lake-level fluctuations based on tree stumps uncovered as the water receded, lacustrine deposits containing buried soils, and bison skulls. Aronow indicated that Devils Lake rose to its outlet altitude of 1,453 ft above sea level (fig. 14) at least twice since the retreat of Pleistocene glaciers about 10,000 years ago. Callender (1968) studied the postglacial sedimen- tology of Devils Lake and reconstructed the recession of the lake from the chemical contents of core samples. Callender's chronology which extends from about 6,000 years ago indicates that a substantial fluctuation in water-surface altitude of Devils Lake has occurred in response to climatic variations. His findings corrobo- rate much of Aronow's research. Numerous reasons for the lake-level fluctuations have been proposed and debated (Swenson and Colby, 1955, p. 8). In the early 1900's, the popular theory was that human settlement in the 1880's and subsequent breaking of the "impermeable" sod caused a reduction in runoff. According to this theory, the water table was lowered because of related increases in evapotranspira- tion (Horton and others, 1910; Simpson, 1912). However, as the water-surface altitude of Devils Lake rose in the 1940's, support for this theory declined. Swenson and Colby (1955) indicated that, based on limited climatic data, fluctuations in lake levels were caused by climatic change. Langbein (1961), however, stated that the decline in water-surface altitude from 1867 to 1940 was greater than can be accounted for by changes in climate and the negligible amount of irriga- tion that had occurred. Although it is certain that both climatic variability and human modifications of the drainage basin of Devils Lake are affecting lake-level fluctuations, addi- tional interpretation and analysis of data will be re- quired before the relative importance of the various processes controlling lake levels can be completely un- derstood. Currently, studies are underway to achieve this understanding. SELECTED REFERENCES ON RISING LAKE LEVELS Arnow, Ted, 1984, Water-level and water-quality changes in Great Salt Lake, Utah, 1847-1983: U.S. Geological Survey Circular 913, 22 p. Aronow, Saul, 1957, On the postglacial history of the Devils Lake region, North Dakota: Journal of Geology, v. 65, no. 4, p. 410-427. Callender, Edward, 1968, The postglacial sedimentology of Devils Lake, North Dakota: Ph.D. dissertation, Universi- ty of North Dakota, 312 p. de Martonne, Emmanuel, 1927, Regions of interior-basin drainage: Geographical Review, v. 27, p. 411. Hahl, D. C., and Langford, R. H., 1964, Dissolved-mineral inflow to Great Salt Lake and chemical characteristics of the Salt Lake brine: Utah Geological and Mineralogical Survey Water-Resources Bulletin 3, Part 11,40 p. Horton, A. H., Chandler, E. F., and Bolster, R. H., 1910, Surface-water supply of the United States, 1907-08: U.S. Geological Survey Water-Supply Paper 245, p. 38-67. Langbein, W. B., 1961, Salinity and hydrology of closed lakes: U.S. Geological Survey Professional Paper 412, 20 p. North Dakota State Engineer, 1944, Fourth report of State Water Conservation Commission and 21st biennium report of State Engineer of North Dakota. Scott, W. E., Schroba, R. R., and McCoy, W. D., 1982, Guidebook for the 1982 Friends of the Pleistocene, Rocky Mountain Cell, field trip to Little Valley and Jordan Valley, Utah: U.S. Geological Survey Open-File Report 82-845, 59 p. Simpson, H. E., 1912, Physiography of the Devils-Stump Lake region, North Dakota: North Dakota Geological Survey, 6th Biennial Report, p. 101-157. Swenson, H. A., and Colby, B. R., 1955, Chemical quality of surface waters in Devils Lake basin, North Dakota: U.S. Geological Survey Water-Supply Paper 1295, 82 p. U.S. Geological Survey, 1980, Water resources data for North Dakota: U.S. Geological Survey Water-Data Report ND-79-l,p. 784. Utah Division of Water Resources, 1984, Great Salt Lake, summary of technical investigations for water level con- trol alternatives: Salt Lake City, Utah Division of Water Resources, 100 p. Whaley, B. L., 1984, Water supply outlook for Utah, May 1, 1984: Salt Lake City, U.S. Soil Conservation Service, 38 p. Winter, T. C., Benson, R. D., Engberg, R. H., Wiche, G. J., Emerson, D. G., Crosby, O. A., and Miller, J. E., 1984, Synopsis of ground-water and surface-water resources of North Dakota: U.S. Geological Survey Open-File Report 84-732, 127 p. 36 National Water Summary 1984 Hydrologic Conditions and Events Floods Floods were prominent hydrologic events throughout the Nation during water year 1984. (See "Overview of Water Year 1984 Hydrologic Conditions and Water- Related Events.") Damage caused by these floods was an estimated $3.5 to $4 billion the third highest amount for the period 1975-84 (U.S. Army Corps of Engineers, 1985). This section describes, in some detail, two areas of major flooding, one in the East and the other in the Midwest. Also described is the unusually large spring runoff in the Colorado River basin. Figure 15. Flooding along Route 7 in New Milford, Conn., caused by overflow of the Housatonic River, May 31, 1984. View is looking north along Route 7. (Photograph courtesy of Michael McAndrews and the Hartford Courant.) National Water Summary 1984 Selected Events 37 RECORD LATE-SPRING 1984 FLOODS IN NEW ENGLAND By Richard A. Fontaine Springtime flooding as a result of snowmelt com- bined with moderate rainfall is a normal pattern that generally occurs from about mid-March through mid- May in New England. In late May 1984, however, a series of extratropical storms, associated with a deep, upper-level trough of low pressure, moved across New England. These storms brought eight consecutive days of rain to some parts of the region and caused extensive damage (figs. 15 and 16). From May 28 through June 3, precipitation ranged from 3 to 5 inches (in.) in the northern parts of Maine, New Hampshire, and Ver- mont to 9 in. or more in the hilly and mountainous areas of northern and western Connecticut and Massa- chusetts, in southwestern Maine, and in southern New Hampshire and Vermont. In Maine, the May precipitation, as reported by the National Weather Service, averaged 235 percent of normal. At individual sites in Maine, totals ranged from 129 to 325 percent of normal. Precipitation at Portland, Maine, set a new record total for May of 9.64 in. The same pattern of record-breaking precipitation for May was noted throughout New England. Runoff in response to this record rainfall varied widely throughout New England. Floods with recur- rence intervals that ranged from 5 to 25 years occurred on most streams, although flooding on some streams was considerably more severe with recurrence intervals that ranged from 35 to 100 years (table 2). Locally intense rainfall contributed to record or near-record flooding on the Winnipesaukee and Ashuelot Rivers in New Hampshire. The Kennebec River basin in Maine and the Housatonic and Connecticut River basins in Massachusetts and Connecticut had record or near- record flooding that was primarily in response to the large areal extent of the intense rainfall. Peak dis- charges at selected sites (fig. 17) are summarized in table 2. Figure 16. Aftermath of flooding in central Vermont, June 7,1984. The remains of a home destroyed when floodwaters undercut 50 feet of embankment behind the structure located in the foreground. View is upstream on Great Brook in Plainfield, Vt. (Photograph courtesy of Toby Talbot, Associated Press photographer.) 38 National Water Summary 1984 Hydrologic Conditions and Events Table 2. Peak discharge at selected stream sites caused by the New England storm, May 28 to June 3,1984 [do = ditto, ft3/s = cubic feet per second. Data from U.S. Geological Survey files] Site no. on fig. 17 1 2 3 4 5 6 7 8 9 10 11 River and station location Kennebec River: Winnipesaukee River: Tilton.N.H. --------- Ashuelot River: Hinsdale, N.H. -------- Housatonic River: Great Barrington, Mass. - - - - Falls Village, Conn. ------ Connecticut River: Thompsonville, Conn. ----- Date do-- May 31 May 31 do do do- June 1 do- June 2 Peak discharge (ft3/s) Ijro f\Tlf\ 2-if) ono U 500 2i4 ono 10,200 21,100 34 OflO 140 ono 186,000 IQO ono i c£ nnn Approximate recurrence interval (years) 100 100 100 100 60 70 35 50 50 65 75 Length of record (years) 56 B1 47 74 71 72 44 on 56 Bfl 20 Highest peak discharge of record. ' Second-highest peak discharge of record. '""HSt. Albans" ? 7 Johnson rl ,s~ Plainfied WellsR IVERMONT /HAMPSHIRE} . / li Winnipesaukee f V--- MASSACHUSETTS C CONNECTICUT j RI ^ ^ 7New10 . /Salmon R \, ; t*Milford /* \ . J ' J M' East ^Hampton Figure 17. Areas of New England flooded in 1984 by late- spring floods. Numbers show location of stations listed in table 2. The May 28 to June 3 storm caused extensive damage throughout New England. Several hundred people were forced to evacuate their homes, and agricultural losses were severe. An account published in the Springfield, Mass., Morning Union newspaper (June 1, 1984) estimated agricultural damage to be as much as $30 million in the Connecticut River Valley of Massachusetts alone. Flooding, such as that in New Milford, Conn., depicted by figure 15, was common- place. New Milford is located on the Housatonic River, about 7 miles (mi) downstream from the U.S. Geologi- cal Survey stream gage at Gaylordsville (table 2). Residents of central Vermont who did not experi- ence the extreme flooding from the May 28 to June 3 storm were not as fortunate the following week. An intense band of thundershowers traversed Vermont from St. Albans in a southeasterly direction to Wells River near the New Hampshire border on the evening of June 6 and the morning of June 7. The storm dumped from 2 to 5 in. of rain in an area where soils were saturated from the rains of the previous week. Flash floods occurred throughout Franklin, Lamoille, and Washington Counties. Figure 16 depicts damage that was typical in this area. A peak discharge of 13,600 cubic feet per second (ftVsec) was recorded on June 7 on the Lamoille River at Johnson, Vt. This peak had a recurrence interval greater than 100 years and was the second-highest peak discharge recorded at the site in 57 years of record. The late-spring floods of 1984 in New England also were abnormal because of the unusually late time of the year in which they occurred. In New England, flooding in the early spring is much more common. It typically National Water Summary 1984 Selected Events 39 occurs in response to snowmelt that is accelerated by seasonally warm temperatures or rainfall or a combina- tion of both. Spring floods may be intensified by several factors, mainly frozen or saturated soils that retard infiltration. The probability of flooding is de- creased once the snow has melted, the soils have thawed and drained, and evapotranspiration has increased in response to plant growth and elevated temperatures. Thus, most annual peak discharges of New England streams occur in March and April each year. Annual peak discharges, for example, on the Pis- cataquis River near Dover-Foxcroft, Maine (fig. 18), occurred during the spring months 63 percent of the time over the period from 1903 to 1983. Of these peaks, 88 percent occur in the first half of the spring season (March 20-May 8). In southern and coastal New Eng- land, 73 percent of the annual peak discharges on streams such as the Salmon River near East Hampton, Conn., occur from midwinter to early spring. Only twice in the 55-year period of record at the Salmon River station has an annual peak discharge occurred during the months of May or June. In summary, the late-spring floods of 1984 in New England were unusual, not only because of their magni- tude, but also because of their late occurrence in the year. 35 30 25 20 15 10 5 n D Piscataquis River, 1903-83 (northern New England) "fl" Salmon River, 1929-83 (southern New England) ' ~\ -i 1 r pi r ; 1 :-. n n fTl OCT NOV DEC JAN FEE MAR APR MAY JUNE JULY AUG SEPT MONTH OF WATER YEAR Figure 18. Monthly occurrence of annual peak discharges for the period of record of the Salmon River near East Hamp- ton, Conn., and the Piscataquis River near Dover-Foxcroft, Maine. (Source: Compiled by Richard Fontaine from U.S. Geological Survey data.) 40 National Water Summary 1984 Hydrologic Conditions and Events JUNE 1984 FLOODS ON THE MISSOURI RIVER AND TRIBUTARIES By I. L. Burmeister Heavy rains in South Dakota, Nebraska, and Iowa during a 3-week period in June 1984 caused extensive flooding on streams in those States and along the Missouri River from Sioux City, Iowa, to Rulo, Nebr. Although June floods are common in the Midwest, a persistent climatological pattern across the United States led to unusually serious flooding this year. At the surface and in the upper air, a nearly stationary ridge of high pressure was established over the Southeastern United States, while a similarly stationary trough of low pressure settled over the Western States. The western trough produced cool temperatures and numerous storm systems which moved eastward toward the Great Plains and intensified as they mixed with the warm moist Gulf air pushed north by the high pressure in the Southeast. The succession of cyclones and frontal passages produced many intense and widespread rain- storms. Nebraska and Iowa last experienced this type of weather pattern in 1967, when similar flooding occurred (Osugi, 1984). Major Nebraska flood areas were Louisville and Plattsmouth along the Platte River and Nebraska City and Rulo along the Missouri River (fig. 19). On June 14, the Platte River at Louisville peaked at a flow of 144,000 cubic feet per second (ft3/s) exceeding the previous record of 124,000 ft3/s that occurred on March 30, 1960. The flow on June 14 was a combina- tion of sustained high seasonal releases from upstream Figure 19. Area of June 1984 floods on the Missouri River and tributaries. reservoirs (in anticipation of high runoff from later snowmelt) and flooding along tributaries to the Platte River (including Salt Creek, Loup River, and Elkhorn River). At Plattsmouth, downstream from Louisville, the water and waste-treatment plants, businesses, and homes were flooded for many days. Although high flows on the Platte River were a major factor in the downstream flooding at Nebraska City and Rulo along the Missouri River, a combination of other factors also contributed to the flooding. Sever- al intense thunderstorms in eastern Nebraska, eastern South Dakota, and western Iowa produced accumula- tive rainfall totals of 10 to 13 inches (in.). Amounts of 6 to 10 in. fell in several 24-hour periods. As a result, flood crests of major tributaries other than the Platte River significantly added to the Missouri River crest; for example, during this period, the Big Blue River had the second-highest discharge of record, the Little Blue River had a record discharge, Weeping Water Creek discharge was second highest of record, and the Nish- nabotna River had a record water height. Another contributing factor was that upstream from Rulo, a levee was breached on the Missouri State side and caused flooding at Big Lake State Park and the sur- rounding area. Many homes, cabins, marinas, bridges, and highways suffered flood damage (fig. 20). Another crest reached Nebraska City and Rulo on June 26 and 29, respectively. This flooding was caused by high runoff from thunderstorms in eastern South Dakota, northeastern Nebraska, and northwestern Iowa. Record flows were recorded on the James, Ver- million, and Little Sioux Rivers. The Missouri River at Sioux City, Iowa, even with controlled releases at the Missouri River dams at and above Gavins Point Dam (just upstream from James River), reached its second- highest stage of record with a discharge of 103,000 ft3/s on June 25. On June 27, the Missouri River crested at Omaha, Nebr., with a discharge of 114,000 ft3/s. Although levees in the Omaha area held, most marinas, riverfront property, country highways, and cropland along the river were flooded for several days. This flooding still did not exceed the record flood at Sioux City, which occurred on April 14, 1952, when the Missouri crested with a discharge of 441,000 ft3/s. Damage from the 1984 floods was very high, par- ticularly in terms of crop loss and soil erosion. The depth and duration of the flood waters on the low-lying cropland caused suffocation of the young plants in the fields. Moreover, because the plants were small and had immature root systems, they provided little protec- tion against soil erosion. The heavy rains saturated the National Water Summary 1984 Selected Events 41 soil early in the 3-week period, resulting in high runoff rates from the rainfall that occurred later. Six counties in Iowa, five in Missouri, and several in Kansas and Nebraska were declared Federal disaster areas. Dam- ages were extensive to croplands in Iowa, Nebraska, and Missouri. The U.S. Army Corps of Engineers halted barge traffic on the Missouri River during the 3-week period of flooding. Two swing-span bridges near Leavenworth, Mo. (upstream from Kansas City), were not opened to barge traffic from June 8 to July 9 because of high water. Consequently, in addition to erosion and crop losses, financial losses to the barge operators and to other businesses and industries dependent on barge transportation were substantial. Figure 20. Aftermath of flooding of the Missouri River at Rulo, Nebr., June 18,1984. High water marks for peak flow on June 16, 1984, were 0.9 foot higher on buildings. (Photograph by V. L Spiers.) 42 National Water Summary 1984 Hydrologic Conditions and Events SPRING 1984 RUNOFF IN THE COLORADO RIVER BASIN By Dannie L. Col I ins Runoff in the Colorado River during the 1984 runoff season (April-July) was much higher than nor- mal for the second consecutive year. This unusually large runoff resulted from very heavy snows in Novem- ber and December augmented by additional heavy snows in April and early May. Examples of the snow- pack variation from the U.S. Soil Conservation Service (1984), for the 1983-84 winter season for the Colorado River watershed in Colorado are as follows: 1984 Average snowpack, in percent of 1961 to 1980 average January 1 - - - - February 1 - - - - March 1 - - - - - April 1- ----- May 1 ----- - 222 160 139 141 169 Heavy snowfall also occurred after May 1 just before the start of the major runoff season. Unseasonably warm temperatures followed the late-spring snow- storms, causing the near-record runoff that began about May 20, 1984. The magnitude of peak flows for the 1984 runoff season varied somewhat but were generally 5 to 10 percent greater than those of 1983. The peak flow of the Colorado River near Cisco, Utah, for example, was 68,500 ft3/s, the largest recorded peak flow since 1917 and 110 percent of the 1983 peak discharge. The estimated recurrence interval for this peak (using the station record for analysis after major storage struc- tures were in place) was about 100 years. An extreme example was the flow of the Uncompahgre River at Delta, Colo. (fig. 21). The peak flow of 5,750 ftVs at that station was more than 1.5 times the estimated 100-year peak flow and 194 percent of the 1983 peak discharge. The Uncompahgre River basin has no major flood-control storage structures. Another indicator of the unusually large runoff in the Colorado River basin during the 1984 runoff season is the inflow into Lake Powell. Flow volumes and their recurrence intervals were computed for the combined flows at the three Utah gaging stations that measure the major inflows into Lake Powell Colorado River near Cisco, Green River at Green River, and San Juan River near Bluff. From May 1 through July 31, 1984, the combined flow volume was 11.8 million acre-ft, which was equal to the flow volume for the same period in 1957, the largest since 1921. The estimated recurrence interval for this flow volume is approximately 35 years. For water year 1984, the combined flow volume was 20.6 million acre-ft; this flow exceeds the 1983 combined flow volume of 19.5 million acre-ft and is the largest annual volume since 1917. The estimated recurrence interval for this annual volume is 100 years. Peak inflow into Lake Powell, which occurred on May 28, 1984, was approximately 122,000 ftVs. Peak outflow from Lake Powell (42,800 ft3/s) began on May 8, 1984, and con- tinued until mid-July. Lake Powell crested at 3,702.5 ft on July 12, 2.5 ft above normal full-pool level. Down- stream at the Hoover Dam outlet, the maximum flow peaked at about 37,500 ftVs on June 25, 1984. Further downstream, the maximum releases from Davis and Parker Dams were about 35,000 ft3/s and 32,500 ftVs, respectively. High releases over a period of 42 days through the Glen Canyon Dam spillways during the 1983 spring runoff resulted in extensive tunnel damage. Repairs, which began in July 1983, included excavation and removal of the tunnel's damaged concrete lining, the filling of cavities eroded in the sandstone, the installa- tion of a new lining, and the construction of airslots in the inclined portions of the spillway tunnel to prevent Figure 21. The Colorado River basin. National Water Summary 1984 Selected Events 43 Figure 22. Flow being released from Glen Canyon Dam, Ariz., May 23,1984. Rate of flow was approximately 42,800 cubic feet per second. (Photograph by U.S. Bureau of Reclamation.) cavitation (or erosion) damage during future operations (U.S. Bureau of Reclamation, 1983, p. 1). Repairs were completed on both spillways during the summer of 1984 and one spillway was tested successfully in August 1984 (U.S. Bureau of Reclamation, 1984, p. 1-2). Larger than normal releases from all major reser- voirs within the basin were begun in late fall 1983 and continued through spring and summer 1984 in anticipa- tion of runoff forecast to be higher than normal (fig. 22). These releases caused continued minor flooding in some downstream areas that had been flooded in 1983. Releases at Glen Canyon Dam were increased to 42,800 ft3/s in May as inflows to Lake Powell were forecast to be 197 percent of normal. The sequence of operations throughout the year enabled the Colorado River Stor- age Project to accomodate the largest annual volume of runoff in the basin since 1917. Peak flows along the lower Colorado River downstream from Davis Dam were about 10,000 ft3/s less than the damaging flows of 1983. If additional flood storage space had not been made available, peak flows would have been much higher and flooding would have been severe and wide- spread. Instead, flood damage in the basin during the 1984 runoff season was minor except in some areas adjacent to uncontrolled streams in the upstream part of the basin. SELECTED REFERENCES ON FLOODS Osugi, R. M., 1984, Monthly report of river and flood condi- tions: Omaha, Nebr., National Oceanic and Atmospher- ic Administration, National Weather Service, 5 p. U.S. Army Corps of Engineers, 1985, Annual flood damage report fiscal year 1984. U.S. Army Corps of Engineers Report DAEN-CWH-W, 12 p. U.S. Bureau of Reclamation, 1983, Upper Colorado Region readying for runoff: The Spillway, v. 4, no. 12, p. 1-2. __1984, Glen gets A-plus on spillway test: The Spillway, v. 5, no. 8, p. 1-2. U.S. Soil Conservation Service, 1984, Colorado and New Mexico Water Supply Outlook: Denver, Colo., U.S. Department of Agriculture, Soil Conservation Service, 8 p. 44 National Water Summary 1984 Hydrologic Conditions and Events Water Quality The discovery of relatively high and toxic concentrations of selenium in irrigation return flows along the west side of the San Joaquin Valley of California is a matter of concern to many different groups. Although it is not a hydrologic event in the sense of a flood or drought, it is a notable example of how human activities can seriously affect water quality. Figure 23. View of the Kesterson Reservoir, San Joaquin Valley, Calif., (looking west) showing the San Luis Drain (foreground) and evaporation ponds (background). (Photograph by S. J. Deverel.) National Water Summary 1984 Selected Events 45 SELENIUM IN THE SAN JOAQUIN VALLEY OF CALIFORNIA By Steven J. Deverel In 1983, the U.S. Fish and Wildlife Service found deformities and a high mortality rate in newborn and embryonic coots, grebes, stilts, and ducks nesting at the Kesterson National Wildlife Refuge near Gustine, Calif, (fig. 23). Those symptoms matched embryonic and developmental deformities in chickens attributed to selenium poisoning described by the National Research Council (1977, p. 205-488). Selenium concentrations in fish and bird tissues from the Kesterson refuge were found to be considerably higher than those at nearby wetland wildlife areas not receiving agricultural drain- age water (U.S. Bureau of Reclamation, 1984). Selenium, a naturally occurring, nonmetallic ele- ment present in the soils and ground water of the west side of the San Joaquin Valley in California, is believed to be essential to human and animal nutrition in minute amounts but can be toxic at relatively low concentra- tions. Agricultural drainage water from part of the west side of the San Joaquin Valley flows into the wetland wildlife refuge, which was developed as part of the San Luis Drain, a drainage canal constructed to aid agricul- ture in the area (fig. 24). The selenium present in the drainage water is believed to originate from sedimentary rocks of marine origin in the California Coast Range, which has been eroded to form the valley-fill deposits along the west side of the San Joaquin Valley. These valley soils are underlain by a shallow, impermeable clay layer that restricts the downward drainage of applied irrigation water. This irrigation water is essen- tial to farming of about 1.2 million acres in this semi- arid region. Because the clay layer restricts downward move- ment of water, the water accumulates close to the land surface. When water levels rise to the point that the root zone becomes saturated, plant growth may be inhibited, and salts can accumulate near the soil sur- face. Salts present in the irrigation water and soil are left behind as the shallow water evaporates and as the plants extract water from the soil. This can create saline conditions in the crop-root zone to a degree that de- creases agricultural productivity. The U.S. Bureau of Reclamation estimates that about 253,000 acres in the San Joaquin Valley are affected by inadequate drainage of salts and leaching water (U.S. Bureau of Reclama- tion, 1984). To remove the drainage water from the valley, the Bureau started construction of a discharge canal in 1968, the San Luis Drain (fig. 24), to carry the water from the west side of the valley ultimately to a proposed outlet in Suisun Bay in the Sacramento-San Joaquin Delta, where the two major rivers of California's Central Valley flow into the San Francisco Bay. The completed drain would provide a drainage outlet for about 493,000 acres of irrigated land. EXPLANATION Existing San Luis Drain Proposed extensions of San Luis Drain Kesterson Reservoir Kettleman City CALIFORNIA Bakersfield 32 MILES J Figure 24. The existing and the proposed San Luis Drain, San Joaquin Valley, Calif. In 1975, 85 miles (mi) of the proposed 207-mi-long San Luis Drain were completed from Five Points, Calif., to a temporary discharge point at Kesterson Reservoir which, by agreement between the U.S. 46 National Water Summary 1984 Hydrologic Conditions and Events Bureau of Reclamation and the U.S. Fish and Wildlife Service, was designated Kesterson National Wildlife Refuge (fig. 24). In 1978, the U.S. Bureau of Reclama- tion began discharging water from the San Luis Drain into the wildlife refuge, which is managed cooperatively by the U.S. Fish and Wildlife Service and the U.S. Bureau of Reclamation. The drain presently (1984) provides a drainage outlet for about 8,000 acres. In 1982, the U.S. Fish and Wildlife Service found that selenium levels in the fish at Kesterson Reservoir were 100 times the levels in fish from an adjacent State wildlife area that did not receive agricultural drainage water (U.S. Bureau of Reclamation, 1984). Total dis- solved selenium concentrations in the drainage water flowing into the San Luis Drain and in the water in the Kesterson Reservoir subsequently were found to range from 0.1 to 1.4 milligrams per liter (mg/L) (Presser and Barnes, 1984, p. 8). Water taken from farm-drain systems to be serviced by the proposed completed drain was found to contain selenium concentrations as high as 4.2 mg/L. In a recently completed study of the areal distribution of selenium in the shallow ground water (Deverel and others, 1984), the proposed San Luis Drain service area was divided in three zones based on topography and soils. The alluvial fan zone, which includes the gently sloping deposits on the western edge of the service area, and the basin rim zone, which includes the level part of the valley between the alluvial fan and the San Joaquin River basin, had the highest selenium concentrations. The minimum limit for clas- sification of dissolved selenium as a hazardous waste has been set at 1 mg/L by the U.S. Environmental Protection Agency (1980, p. 33122). In drinking water the criterion is 0.01 mg/L (U.S. Environmental Protec- tion Agency, 1982); however, these farm-drain systems are not part of a domestic water supply. Selenium toxicity has been observed in other parts of the world where livestock consume forage crops and grains that have high selenium contents. Chronic selenosis in cattle and sheep is manifested by weight loss and muscle dysfunction. At the other extreme, minute amounts of selenium are added to the diet of livestock in areas that lack selenium to prevent dietary deficien- cies. According to Lakin (1973, p. 97), "Selenium is an essential nutrient for animals [and humans] and is required at a concentration level of about 40 ppb [parts per billion; 0.040 milligrams per liter (mg/L)] in their diet; at concentrations of 4,000 ppb [4.0 mg/L] and above, however, it becomes toxic to animals." Additional work is needed to define the extent and severity of the water-quality problem in the San Joaquin Valley. Areas of concern include: The source and areal extent of selenium in the San Joaquin Valley, The geochemical processes controlling selenium mo- bility in the soil, The potential effects of discharging drainage water into the Sacramento-San Joaquin Delta and San Francisco Bay, Possible treatment for removal of selenium from drainage water, and The toxic effects of selenium on waterfowl and aquatic organisms. A number of government agencies have ongoing studies or have proposed studies to address these topics. SELECTED REFERENCES Brooks, A. S., 1984, Selenium in the environment An old problem with new concerns, in Workshop proceedings The effect of trace elements on aquatic ecosystems: Palo Alto, Calif., Electric Power Research Institute, EA-3329, p. 2-1-2-7. Deverel, S. J., and others, 1984, Areal distribution of seleni- um and other inorganic constituents in shallow ground water of the San Luis Drain service area, San Joaquin Valley, California A preliminary study: U.S. Geologi- cal Survey Water-Resources Investigation Report 84-4319, 67 p. Izbicki, J. A., 1984, Chemical quality of water at 14 sites near Kesterson National Wildlife Refuge, Fresno and Merced Counties, California: U.S. Geological Survey Open-File Report 84-582, 9 p. Lakin, H. W., 1973, Selenium in our environment, in Kothny, E. L., ed., Trace elements in the environment: American Chemical Society, Advances in Chemistry Series 123, p. 76-111. National Research Council, Safe Drinking Water Committee, 1977, Drinking water and health: Washington, D.C., National Academy Press, 939 p. Presser, T. S., and Barnes, Ivan, 1984, Selenium concentra- tions in waters tributary to and in the vicinity of Kester- son National Wildlife Refuge, Fresno and Merced Coun- ties, California: U.S. Geological Survey Water- Resources Investigations Report 84-4122, 26 p. U.S. Bureau of Reclamation, 1984, Information on Kesterson Reservoir and waterfowl: U.S. Bureau of Reclamation Information Bulletin No. 2, 11 p. U.S. Environmental Protection Agency, 1980, Hazardous waste management system: Federal Register, v. 45, no. 98, p. 33063-33122. __1982, Maximum contaminant levels (subpart B of part 141, National interim primary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, parts 100-149, revised as of July 1,1982, p. 315-318. Hydrologic Perspectives on Water Issues II_ 47 48 National Water Summary 1984 Hydrologic Perspectives Introduction The articles in this part of the 1984 National Water Summary are grouped under the headings "Water-Quality Issues" and "Water-Availability Issues." Each was selected because it provides a useful insight into an important aspect of water quality and supply. A synopsis of each article is given below. As in the foregoing description of significant hydrologic events, the authors of each article are identified. Articles under the heading "Water-Quality Issues" examine variations in the concentrations, loads, and trends of five water-quality constituents (sediment, dissolved solids, phosphorus, nitrogen, and pesticides) commonly associated with nonpoint- source pollution of surface water. Progress in the control of point sources of pollution of surface water, such as discharges from industrial and mun- icipal waste-treatment plants, has focused attention on the need to reduce nonpoint-source pollution in runoff from agricultural and urban areas to further improve surface-water quality (U.S. Environmental Protection Agency, 1984a); for example, the U.S. Environmental Protection Agency and the U.S. Fish and Wildlife Service estimate that nonpoint sources of pollution contribute to water-quality problems in 38 percent of all waters and are a major concern in 19 percent of those waters (Judy and others, 1984). The U.S. Environmental Protection Agency (1984b) found that, in about 20 percent of the States, non- point sources of pollution are considered the most important cause of water-quality problems. Of the five constituents discussed here, suspend- ed sediment is presented first ("Sediment in Rivers of the United States") because of the dual role sediment transported by rivers plays in determining water quality: the direct effects of sediment concentrations and loads and the transport of phosphorus and other contaminants, such as pesticides, radionuclides, and toxic metals, that can be adsorbed onto the sediment particles and travel with the sediment. Erosion has long been recognized as an agricultural problem and a potential threat to the continued productivity of the land but only recently has attention been given to the consequent offsite effects of sediment runoff. Not all sediment eroded from a field immediately makes its way into a stream, and the sediment that does reach a water course may be stored in the local stream basin or be trapped behind a dam for many years before moving downstream. An understand- ing of sediment-transport processes and changes in sediment concentrations and loads in streams is important in relating the phenomena to specific soil-erosion-control practices. Following the discussion of sediment is a presentation of the distribution of dissolved solids and the nutrients, phosphorus and inorganic nitro- gen ("Loads and Concentrations of Dissolved Solids, Phosphorus, and Inorganic Nitrogen at U.S. Geo- logical Survey National Stream Quality Accounting Network Stations") and a brief discussion of trends and their possible causes and interpretation ("Trends in Concentrations of Dissolved Solids, Suspended Sediment, Phosphorus, and Inorganic Nitrogen at U.S. Geological Survey National Stream Quality Accounting Network Stations"). Both articles are based on continuing analyses of data from the U.S. Geological Survey's National Stream Quality Ac- counting Network (NASQAN). Two major rivers that have some of the highest dissolved-solids concentra- tions in the country, the Colorado and the Arkansas, are discussed as specific examples of problems that may be associated with this water-quality character- istic. An analysis of information collected by the U.S. Geological Survey and the U.S. Environmental Protection Agency's Pesticide Monitoring Network during water years 1975 to 1980 ("Pesticides in Rivers of the United States") concludes the discus- sion of surface-water quality. Although information on the occurrence of synthetic organic substances and toxic chemicals in ground water is very sparse, information on a na- tional scale can be assembled on the occurrence of some of the more common water-quality constitu- ents. One of these constituents, nitrogen, is the subject of the article, "An Overview of the Occur- rence of Nitrate in Ground Water of the United States." Under the heading "Water-Availability Issues," the effects of water-resources development on ground-water levels in five areas of the country where water table or artesian water levels are more than 40 feet below predevelopment levels in at least one aquifer (U.S. Geological Survey, 1984, p. 40) are examined. The article is titled "Ground-Water-Level Changes in Five Areas of the United States." A related article, "Declining Ground-Water Levels and Increased Pumping Costs: Floyd County,Texas A Case Study," presents detailed information on the cost of ground-water withdrawals in relation to increased energy prices and changes in water levels. These examples of the results of intensive ground- water development in different hydrogeologic set- tings provide a background for interpreting the hydrographs shown in each description of ground- water resources in the "State Summaries of Ground- Water Resources" part of this report. SELECTED REFERENCES Judy, R. D., Jr., Seely, P. N., Murray, T. M., Svirsky, S. C., Whitworth, M. R., and Ischinger, L. S., 1984, 1982 National fisheries survey, v. 1, Technical report, initial findings: U.S. Fish and Wildlife Service, Report No. FWS/OBS-84/06, 140 p. U.S. Environmental Protection Agency, 1984a, Report to Congress Nonpoint source pollution in the U.S.: Washington, D.C., U.S. Environmental Protection Agency, Office of Water Program Operations, Water Planning Division. __1984b, National water quality inventory, 1982 report to Congress: U.S. Environmental Protection Agency, Report EPA 440/2- 84-006, 63 p. U.S. Geological Survey, 1984, National water summary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. National Water Summary 1984 Water-Quality Issues 49 Water-Quality Issues SEDIMENT IN RIVERS OF THE UNITED STATES By Robert H. Meade and Randolph S. Parker INTRODUCTION Sediment ranks high among the substances that are supplied to rivers by nonpoint sources. Part of the sediment supplied to rivers is a natural consequence of the geologic processes that erode the continents and transport the eroded material as sediment to the oceans. The rest of the sediment in rivers, which may be most of the sediment in some heavily affected rivers, is a consequence of the accelerated ero- sion that follows such human activities as forest clearing, crop farming, surface mining, and construction. Because most of the sediments supplied to rivers come from diffuse sources, whether they are induced naturally or artificial- ly, the sources are difficult to identify, predict, and control. Adding to the difficulties of predicting sediment inputs to rivers is the complexity of estimating the rate of sediment delivery. Al- though onsite erosion of specific types of soils under specific conditions of cultivation or other land uses can be predicted by using such tools as the Universal Soil Loss Equation (Wischmei- er and Smith, 1965), predicting how much of the eroded soil will be delivered eventually to the channel of a neighboring stream still re- mains difficult. Sediment that has been eroded off upland fields often is deposited on hillslopes or in the upper parts of stream valleys before it reaches a water course. The length of time during which the sediment is stored in this manner can range from a few days to hundreds of years. Consequently, the sediment that one observes in a river channel today may represent episodes of erosion that took place decades or even a century ago. Once it reaches a stream channel, sediment may cause a number of problems. By raising the elevation of the channel bed, increased sedimentation can lead to increased flooding due to a decrease in the carrying capacity of the stream channel. Sediment affects the mainte- nance of in-channel structures, navigation sys- tems, and other works in the river environment. Furthermore, sediment particles adsorb many contaminants, such as pesticides, radionu- clides, and toxic metals, that are transported, deposited, and stored as part of the sedimen- tary component of the riverine system. After first describing some general charac- teristics of sediment in rivers of the United States, this article will discuss some of the more prominent issues involving sediment. By way of introduction, figures 25 and 26 show sus- pended-sediment discharges at the mouths of selected rivers. In the conterminous United States (fig. 25), the patterns of suspended-sediment concentra- tion reflect such influencing factors as climate (especially rainfall) and the properties of the rocks and soils that are exposed to erosion. In the Eastern and Northwestern States, suspend- ed-sediment concentrations generally are low, except in two areas: parts of western Mississip- pi, western and central Tennessee, Illinois, and Iowa that are underlain by loess (easily credible windblown silt deposits) and southwestern Washington, where the recent eruption of Mount St. Helens has added large quantities of sediment to the lower Columbia River stream system. On the High Plains of South Dakota, Colorado, Oklahoma, Texas, and New Mexico, consistently large concentrations of suspended sediment are the result of a combination of easily eroded sedimentary rocks and relatively little protective vegetation. Although intense rainfall events on the High Plains are frequent enough to cause significant erosion, the total amount of precipitation is too small to allow the development of the kind of vegetation that would protect the soil from erosion (Langbein and Schumm, 1958). Similar combinations of credible soils and sporadic, but intense, rainfall also account for most of the large concentra- tions of suspended sediment in rivers in the Southwestern States. Mean annual suspended-sediment loads discharged to the oceans, in millions of tons per year, are portrayed in figure 25 by half-circles at the mouths of selected rivers. These sedi- ment loads, which are averages as of 1980, reflect a number of artificial influences, not the least of which is the interruption of the down- river flow of sediment by dams and reservoirs. The dominance of the Mississippi River as a mover of sediment is readily apparent. In spite of the large dams that have been built across its major tributaries, the Mississippi River still ranks sixth or seventh in the world in suspended 50 National Water Summary 1984 Hydrologic Perspectives Colorado River Concentration of suspended sediment in rivers, in milligrams per liter Less than 300 300-2000 2000-6000 More than 6000 Discharge of suspended sediment to the coastal zone, in millions of tons per year. (Area of semicircle is proportional to sediment volume) Figure 25. Average concentration of suspended sediment in rivers and average discharge of suspended sediment at the mouths of selected rivers of the conterminous United States. See table 3 for ranking of rivers. (Sources: Concentration map modified from Rainwater, 1962, plate 3; sediment-discharge data compiled by R. S. Parker and R. H. Meade from files of the U.S. Geological Survey, U.S. Army Corps of Engineers, and the International Boundary and Water Commission) Concentration of suspended sediment, in milligrams per liter Less than 500 HH 500-2000 ^^^1 More than 2000 Discharge of suspended sediment to the coastal zone, in millions of tons per year. (Area of semicircle is proportional to sediment volume) Figure 26. Average concentration of suspended sediment in rivers and average discharge of suspended sediment at the mouths of selected large rivers of Alaska. (Source: Compiled by R. H. Meade from U.S. Geological Survey data, including reports by Burrows and Harrold, 1983; Knott and Lipscomb, 1983; and Scott, 1982.) sediment discharge to the oceans (Milliman and Meade, 1983, p. 2). Next in rank in the conter- minous States is the Columbia River, which is shown in figure 25 with two different values of suspended sediment discharge: 10 million tons per year (ton/yr), the average load transported before the 1980 eruption of Mount St. Helens, and 40 million ton/yr, the estimated annual suspended sediment load transported after the eruption. Although over 140 million tons of suspended sediment from Mount St. Helens was discharged by the Cowlitz River into the Columbia River in the first 4 months after the eruption, this discharge has decreased consider- ably in the last few years. The additional sediment attributed to Mount St. Helens has declined to about 30 million ton/yr. Less information is available on the con- centration and discharge of suspended sediment in the rivers of Alaska (fig. 26). It is reasonably certain, however, that suspended sediment con- centrations are low in the rivers of northern and western Alaska. Sediment concentrations are larger in south-central Alaska, where glaciers National Water Summary 1984 Water-Quality Issues 51 erode the mountain slopes and glacial melt- waters carry large sediment loads, but these concentrations still are not as large as those in the arid and semiarid parts of the western conterminous United States. The present-day sediment discharges of three rivers that drain the glaciated peaks of the Alaska Range, the Copper, the Yukon, and the Susitna, rank, respectively, second, third, and fourth, among the rivers of the United States. Ten rivers of the United States that are important by virtue of their large sediment discharges or their large drainage areas are listed in table 3. The sediment discharges of the Mississippi River, the Rio Grande, and the Colorado River have been diminished by dams and reservoirs (discussed later in this article). Although it discharges three-quarters as much water to the ocean as the Mississippi River, the St. Lawrence River carries relatively little sedi- ment because the Great Lakes act as natural sediment traps. Table 3. Discharge of suspended sediment to the coast- al zone by 10 major rivers of the United States, about 1980 [ton/yr = tons per year] Rivers Average annual sediment discharge (million ton/yr) Rivers that discharge the largest sediment loads: Columbia: Before Mount St. Helens eruption ---------- (Since Mount St. Helens eruption-approximate - - - - Rivers with large drainage areas: '230 80 65 25 15 11 10 40) 1.5 .8 .1 Includes Atchafalaya River. EFFECTS OF RESERVOIRS ON SEDIMENT LOADS One of the most pervasive influences on sediment loads is exerted by the dams and reservoirs that have been built in large numbers across the rivers of the United States. Dams are built to impound water for various purposes, and the reservoirs they form interrupt the downriver flow of sediment. Although the river water that enters a reservoir is released eventu- ally (through a powerplant, into a diversion canal, or over a spillway), much of the sediment is trapped permanently in the reservoir. Nearly all reservoirs on major rivers of the United States trap at least one-half of the river sedi- ment that flows into them. Some of the largest reservoirs in the country, like Lake Powell and Lake Mead on the Colorado River, trap virtual- ly all the sediment that flows into them. The effects of reservoirs on sediment loads are apparent in rivers in all parts of the country; however, they are most obvious in the large western rivers where the original sediment loads were naturally large and where the construction of dams has been especially intense. Although dams cause a variety of downstream changes in the configurations of the river channels them- selves (Williams and Wolman, 1984), only the effects of reservoirs on the quantities of the sediment loads transported by rivers are dis- cussed in this article. These effects are well described by extensive collections of data from three large western river systems the Mis- souri-Mississippi, the Rio Grande, and the Colorado and a group of rivers in the Eastern United States (figs. 27, 28, 29, and 30). MISSOURI-MISSISSIPPI RIVER SYSTEM Annual discharges of suspended sediment measured at six gaging stations on the Missouri River and two stations on the Mississippi River over a period of about four decades are shown in figure 27. The Missouri River has always been the principal supplier of sediment to the lower Mississippi River; the other two large components of the Mississippi River system, the upper Mississippi River and the Ohio River, supply large quantities of water but compara- tively small amounts of sediment. When five large dams were completed for irrigation and hydroelectric power above Yankton, S. Dak., between 1953 and 1963, the flow of sediment from the upper Missouri basin virtually was stopped (fig. 27). Following the closure of Fort Randall Dam and Gavins Point Dam in 1953, downstream sediment loads were diminished immediately, and the effect could be observed all the way down to the mouth of the Mississip- pi River. Sediment discharges to the Gulf of Mexico by the Mississippi River are now (1984) less than one-half of what they were before 1953. This decrease in the supply of river sediment is probably a strong contributory factor to a rapid recession of shorelines that is occurring in the subsiding Mississippi delta. Rio GRANDE Sediment loads in the Rio Grande, which flows through New Mexico and also forms the international boundary between Texas and Mexico, have been severely diminished by the 52 National Water Summary 1984 Hydrologic Perspectives Williston Bismarck OAHE DAM 1958 loo^l ¥ p 0 ^^^^^^^^^^Wf*Hrr~n Pierre SHARPE DAM 1963 FORT RANDALL DAM 1953 I GAVINS POINT DAM 1953 M I IZJOiJ uLu [^ I^L Yankton Omaha Kansas City St. Louis Baton Rouge Fort Randall Dam Minr>eapoHs Gavins Point Dam Vankton WATER YEAR Figure 27. Annual discharge of suspended sediment at six stations on the Missouri River and two stations on the Mississippi River showing the effects of reservoirs on downstream sediment loads, 1939 to 1982. (Source: Compiled by R. H. Meade from U.S. Army Corps of Engineers and U.S. Geological Survey data.) National Water Summary 1984 Water-Quality Issues 53 cc LU Q_ to Zo CO o z LUas 1o LU O LU CO6 LU OZ £ CO Z) to 20 Otowi Bridge COCHITI DAM 1974 Albuquerque San Marcial ELEPHANT BUTTE DAM 1915 - A/*** n'm l'T^iaPFS "*f»' y i El Paso 20 r I AMISTAD DAM 1969 f Del Rio Roma Otowi Bridge \ CochitiQam Figure 28. Annual discharge of suspended sediment at six stations on the Rio Grande showing the effects of reservoirs on downstream sediment loads, 1906 to 1983. Years are water years in upper three histograms and calendar years in lower three histograms. (Source: Compiled by D. W. Litke from U.S. Geological Survey and International Boundary and Water Commission data.) 54 National Water Summary 1984 Hydrologic Perspectives dams and reservoirs that were built to divert water for irrigation. Records of annual sedi- ment discharges at six gaging stations on the Rio Grande are summarized graphically in fig- ure 28. These records clearly show the effects of reservoirs on the sediment loads in different parts of the river even though they indicate strong year-to-year fluctuations in sediment discharge that are typical of the irregular dis- charges of water and sediment in arid parts of the country. The records from the uppermost two sta- tions show the effects of the closure of Cochiti Dam in 1974. Before 1974, sediment discharges at Albuquerque were always greater than those recorded upriver at Otowi Bridge; since 1974, however, sediment discharges at Albuquerque generally have been smaller than those at Otowi Bridge. Between Albuquerque and San Mar- cial, the sediment discharge of the Rio Grande is increased markedly by additions from several important tributaries, most notably the Rio Puerco. Records of sediment discharge at San Marcial and El Paso dramatically show the effects of Elephant Butte Reservoir. (See fig. 28.) During the last several decades, suspend- ed-sediment discharges at El Paso have ave- raged only about 200,000 ton/yr, or less than 5 percent of the average discharge at San Marcial during the same period. Below El Paso, the sediment discharge of the Rio Grande is in- creased again by contributions from two more tributaries, the Rio Conchos from the Mexican side and the Pecos River from the Texas side. These added contributions of sediment have been trapped, however, behind Falcon Dam, which closed in 1953, and Amistad Dam, which closed in 1969. The discharge of suspended sediment to the Gulf of Mexico by the Rio Grande, which was on the order of 20 million ton/yr as recently as 1940 and probably was even greater before Elephant Butte Dam was closed in 1915, now averages less than 1 million ton/yr. COLORADO RIVER Perhaps the classic example in the United States of the interruption of a large discharge of river sediment to the oceans is that of the Colorado River. Before about 1930, the Colorado River delivered an average of 125 to 150 million tons of suspended sediment per year to its delta at the head of the Gulf of Califor- nia. Since the closure of Hoover Dam, which began in 1935, this rate of sediment delivery has declined, first precipitously and then more gradually, to an average annual amount today of about 100,000 tons. Figure 29 graphically shows this decline in sediment and also the more gradual decline of water flow in the lowermost Colorado River since the turn of the century. Aside from a period between 1934 and 1938, when 25 million acre-ft of the river water was appropriated for the initial filling of Lake Mead behind Hoover Dam, the quantity of water carried by the Colorado River past Yuma, Ariz., has declined more or less progres- sively. This decline has been in response to the increasing diversion of water from the Colora- do River for irrigation of croplands and for municipal water supplies. The more abrupt decline in sediment discharge at Yuma clearly was related to a single event, the closing of Hoover Dam. The example of the Colorado River is altogether analogous to that of the Nile River of Egypt, which formerly carried more than 100 million ton/yr of sediment past Cairo to its delta in the Mediterranean Sea, and which now (since the completion of the high dam at Aswan) discharges virtually no sediment or water to the sea. SOUTHWESTERN ATLANTIC SEABOARD To avoid the impression that interruption of the seaward transport of sediment by dams and reservoirs is a phenomenon confined to the western part of the country, figure 30 is pre- sented to show the effects of reservoirs on the sediment loads of rivers in Georgia and the Carolinas. Although continuous records of sediment discharge, such as those shown in figures 27 to 29, are not available for these rivers, enough data were available to compare measurements made about 1910 with data col- lected about 1980. During the years between the two World Wars, many dams were built across these rivers, mostly for hydroelectric power and flood control. A comparison of the sediment loads before (about 1910) and after (about 1980) shows the large influence of these reservoirs in trapping sediment. As shown in figure 30, five major rivers, which previously carried a total of 10 million ton/yr of sediment to the coastal zone, now carry only about one-third of that amount. STORAGE OF SEDIMENT IN RIVER SYSTEMS The 1983 National Water Summary (U.S. Geological Survey, 1984, p. 68-69) emphasized the importance of sediment storage in the over- all picture of erosion and sedimentation. It points out that, on a national scale, the amount of sediment delivered to the oceans by rivers was only about 10 percent of the total amount eroded off the uplands of the country and that National Water Summary 1984 Water-Quality Issues 55 i j 11111111 u 11 H it) 111111111111111111 ii i u ]rn Figure 29. Annual discharge of water (1905-64) and suspended sediment (1911-79) in the Colorado River at Yuma, Ariz. Large sediment discharges shown for the years through 1940 may be somewhat exaggerated; these data were collected before modern sediment samplers and techniques were developed and standard- ized. However, this does not detract from the observation that the abrupt decrease in suspended-sediment discharge in the middle 1930's coincided with the closure of Hoover Dam. (Source: Compiled by R. S. Parker from U.S. Geological Survey water-discharge data and U.S. Bureau of Reclamation suspended- sediment data.) 90 percent of the soil eroded in the country was being stored somewhere between erosion sites and the sea. A fraction of this 90 percent is being stored in reservoirs, as discussed in the preceding paragraphs, but most of it is stored in other places, such as on hillslopes, flood plains, and other parts of stream valleys. The implica- tions of the large amount of sediment storage are enormous; for example, because many of the toxic materials that travel in streams, such as metals, radionuclides, pesticides, and other organic substances, are adsorbed tightly onto sediment particles, any accurate prediction of the fate of toxic substances in a stream will require an understanding of what is happening to the sediment. Sediment storage is difficult to 56 National Water Summary 1984 Hydrologic Perspectives Figure 30. Average suspend- ed-sediment discharges of major rivers in Georgia and the Carolinas during two periods, about 1910 and about 1980, that indicate the decrease in sediment loads caused by several reservoirs constructed dur- ing the intervening years. (Source: Compiled by R. H. Meade from U.S. Geologi- cal Survey data.) 0 100 MILES EXPLANATION Suspended-sediment discharge, in millions of tons per year Width of river represents suspended-sediment discharge predict, however, because it involves many different sedimentary processes, operating at a variety of different time scales (Walling, 1983). The following examples serve to illustrate some of these processes. SHORT-TERM STORAGE OF SEDIMENT- LOWER MISSISSIPPI RIVER Short-term (seasonal) storage of sediment in river channels is probably easier to under- stand and predict than long-term storage in river systems. Some of the short-term changes in storage of suspended sediment in the lower reaches of the Mississippi River in Louisiana are shown in figure 31. No dams obstruct these reaches of the Mississippi, no tributaries bring in sediment, and no outlets drain sediment away until it reaches the mouth of the river. Any downriver changes that are observed in the discharges of suspended sediment represent deposition of material onto the riverbed or resuspension of material from the riverbed. At average water discharge, the sediment load remains the same through the entire 300-mile reach of the lower Mississippi; on a net basis, sediment is neither stored nor resuspended at average water discharge. At less-than-average water discharge, the suspended load decreases down the reach; sediment is being dropped by the flowing river and stored on the riverbed. At greater-than-average water discharge, the sedi- ment load increases down the reach; at least part of the previously stored sediment is being resuspended from the riverbed. The short-term pattern, therefore, shows sediment being deposited and stored on the riverbed at lower flows and being resuspended and flushed out to the Gulf of Mexico on higher flows. Analogous patterns of seasonal storage and remobilization of sediment have been observed and described from rivers that range in size from small (Em- mett and others, 1983; Meade and others, 1981) to the largest in the world (Meade and others, 1979, p. 482; 1983, p. 1139-1140). Questions involving the seasonal storage and resuspension of sediment in the lower Mississippi River that need to be studied in- clude the following: What is the long-term balance between storage and resuspension in the long run, is more sediment being stored than resuspended, or vice versa?, and how does the seasonal storage affect the pollutants that are adsorbed on the sediment particles? LONG-TERM (DECADE-TO-CENTURY) STORAGE HYDRAULIC-MINING DEBRIS IN CALIFORNIA A well-known case of long-term movement and storage of sediment in a river system is that of the hydraulic-mining debris in the Sacramen- to River valley of California (Gilbert, 1917; Kelley, 1959). Between 1855 and 1885, enor- mous quantities of sediment were washed into some of the tributaries of the Sacramento River during hydraulic mining for gold. The resulting problems that developed downstream (flood- ing, filling of navigation channels, destruction of flood-plain farms) became so serious that hydraulic mining was curtailed by a court deci- sion in 1884. By that time, however, the large mass of sediment, characterized as a "wave" by G. K. Gilbert (1917), was already into the stream channels and was moving slowly down the tributaries and into the Sacramento River. As the mass of sediment advanced, it raised the National Water Summary 1984 Water-Quality Issues 57 levels of the channel beds, much as an ocean swell raises the level of the sea as it passes through. Bed levels rose 19 feet (ft) in the tributary Yuba River at Marysville and nearly 11 ft in the Sacramento River at Sacramento. The riverbeds at these towns reached their greatest elevations 10 to 20 years after the mining was stopped, and then they declined steadily to their previous elevations during the next 30 to 40 years. All in all, the great wave of hydraulic-mining debris took nearly a century to pass through the channels of the Sacramento River system and finally to reach San Francisco Bay. DISTANCE DOWNSTREAM, IN RIVER MILES Figure 31. Suspended-sediment discharge in the lowermost 300 miles of the Mississippi River at three different stages of river flow less than average, average, and greater than average. (Source: Compiled by R. H. Meade from U.S. Geo- logical Survey data collected by Everett, 1971, p. 14; and Wells, 1980, p. 13.) This pattern, however, applied only to the sediment in and near the river channels. It did not apply to the debris that had overflowed onto the flood plains. The hydraulic-mining debris that was carried out of the river channel during floods and deposited on the flood plains was sufficient in many places to cover entire houses and orchards (Kelley, 1959, p. 134-135, 203-204). Most of that debris still remains where it was deposited a century ago. The time required to remove sediment from storage on the flood plain is much longer than the century that was required to remove the debris from the main river channels. Flood-plain deposits are removed mainly by erosion of channel banks as streams slowly migrate laterally, a process that proceeds at a substantially slower pace than the vertical removal of material stored in the bot- tom of the river channel. LONGER TIME SCALES FOR SEDIMENT STORAGE COON CREEK BASIN, WISCONSIN Many of the problems associated with the prediction of long-term sediment storage are demonstrated in a study carried out on Coon Creek, a small stream that drains 140 square miles of southwestern Wisconsin (Trimble and Lund, 1982). Originally covered by forests, Coon Creek basin was settled by European immigrants and cleared for farming about 1850. As the forests were cleared and the land was plowed, a cycle of erosion and sedimenta- tion began, the consequences of which are still strongly in effect today. In 1933, after about 80 years of land-management practices that result- ed in excessive erosion, soil-conservation ef- forts were begun in earnest. These efforts still continue. Two time periods (1853-1938 and 1938-1975) are described below. The year 1938 was selected as the transitional date because of an extensive sedimentation study that was car- ried out that year. Figure 32A shows the accelerated erosion of sediment from the uplands and tributary areas and the transfer of sediment to the lower hillslopes and valleys of the Coon Creek basin between 1853 and 1938. Much less than 10 percent of the sediment eroded off the uplands during this period was exported out of the basin by the creek. More than 90 percent of the sediment was deposited along the way, on hillslopes and flood plains, where most of it still remains in storage. From 1938 to 1975, improved soil conser- vation and land management reduced the rates of upland erosion. However, the quantity of sediment that passes out the mouth of Coon Creek is still less than 10 percent of the total 58 National Water Summary 1984 Hydrologic Perspectives Figure 32. Sources, sinks, and storage of sediment in the drainage basin of Coon Creek, Wis., during two periods. A, 1853 to 1938. B, 1938 to 1975. Numbers on the diagram are annual averages for the period, in thousands of tons per year. During the 122-year period between 1853 and 1975, a total of 80 million tons of sediment were transferred from eroded upland sources to lowland storage sites within the Coon Creek basin. During that same period, only 5 million tons of sediment were carried out of the basin by the creek. (Source: Modified from Trimble, 1983.) A 1853-1938 Upland sheet and rill Upland erosion gullies 630 Sources of sediment Sediment discharge at mouth 42 78 230 Lower . 42 3D Middle valley Hillslopes 269 Up|and Tributary vaMey valleys valleys Sinks and storage of sediment 96 B. 1938-1975 Upland Sources of sediment sheet and rill Upland erosion gullies 456 71 Tributaries 39 30 Middle valley Sediment discharge at mouth 40 Hillslopes 332 30 153 Lower 42 Middle valley Upland valley valleys Sinks and storage of sediment upland erosion (fig. 325). The other 90 percent or more of the eroded sediment still is being stored within the creek basin. The only impor- tant difference in recent years is that some of the sediment formerly stored in the middle valley is now being remobilized and transported out of the basin. Further details of the Coon Creek study can be found in two recent publications by Trimble and Lund (1982) and Trimble (1983). The study demonstrates the complexity of the sediment-storage problem. The time scales of storage are so long and the storage sites so diverse that it is difficult to even begin to construct mathematical models to predict the eventual rates of sediment movement. As out- lined in a recent summary by Walling (1983), the problems of sediment delivery and long- term storage in river valleys are among the principal challenges for future studies of sedi- ment. EFFECTS OF INFREQUENT LARGE STORMS ON SEDIMENT TRANSPORT In many rivers of the conterminous United States, a large proportion of the sediment load is transported in only a small proportion of the time; for example, within any individual year, more than one-half of the sediment load for the year is likely to be transported in only 5 or 10 days. Also, over a period of many years, a large proportion of the long-term sediment load may be transported in response to a few large, but infrequent, storms. The frequencies of suspended-sediment dis- charge within individual years and the impor- tance of infrequent large storms in producing large sediment loads are demonstrated by the daily suspended-sediment discharge records for three stations Eel River at Scotia, Calif., Delaware River at Trenton, N.J., and Juniata River at Newport, Pa. (fig. 33). The storms whose effects are shown are of two types Atlantic coast hurricanes and Pacific coast winter storms. These three data sets were selected because each contained the effects of a large storm (whose recurrence interval was longer than the period of sediment record), and each contained sufficient data from years of more average sediment discharge to place the effects of the storm into a reasonably comparative context. Figure 33 shows for each year the quantities and proportions of suspended sediment dis- charged during 1, 10, and 100 percent of the year. Among the three rivers, nearly one-half of a year's sediment usually is discharged in 3.65 days, and nearly 90 percent usually is discharged in 36.5 days. EFFECTS OF ATLANTIC COAST HURRICANES ON SUSPENDED-SEDIMENT DISCHARGE The effects of hurricane-induced floods on the sediment discharges of two rivers that drain parts of the middle Atlantic seaboard are shown in figures 33A and B. In both rivers, the suspended-sediment discharges generated by the hurricanes (10 days' discharge on the Jun- iata River and 2 days' discharge on the Dela- ware River) were equivalent to the totals carried during 3 full years of average suspended- sediment discharge. Further, the record for the Delaware River shows that the quantity of suspended sediment carried past Trenton in 2 days following Hurricane Connie was more than the river carried during 5 full years (1962-66) of the mid-1960's drought. In the record for the Juniata River, it is noteworthy that the suspended-sediment discharge during the year of Hurricane Agnes stands alone; during none of the other 31 years in the period of record did the suspended-sediment discharge even approach that recorded during 1972. National Water Summary 1984 Water-Quality Issues 59 EFFECTS OF PACIFIC COAST WINTER STORMS ON SUSPENDED-SEDIMENT DISCHARGE The most spectacular single sediment- discharge event preserved in the daily sediment records of the United States is the storm that struck northwestern California a few days before Christmas 1964 (fig. 33Q. In 3 days, the Eel River carried more sediment past Scotia, Calif., than it had carried during the previous 7 years. In 10 days, it carried a quanti- ty of sediment equivalent to that transported in 10 average years. The total suspended- sediment discharge of 168 million tons that the Eel River carried past Scotia during water year 1965 was almost as great as the 184 million tons that the Mississippi River carried past St. Louis that same year. The storm of December 1964 brought about long-term changes in the sedi- ment-transport characterisitics of many stream channels in northwestern California (Lisle, 1981, 1982). The sediment loads generated by the large storms as shown in figure 33 seem to belong to different statistical populations than do the normal year-to-year sediment loads. The large loads seem to stand alone with no intermediate sediment loads to bridge the wide gaps between them and the more normal loads. This suggests that it may not be possible to predict accurately the large size of these sediment loads merely by extrapolating a sediment record that does not contain at least one of them. Because it is obviously impractical (and impossibly expensive) to continue collecting daily sediment records at each gaging station until one of these large events has been recorded, estimating their frequencies and magnitudes is extremely dif- ficult. CONCLUSIONS Among the issues and problems that relate to the sediment in rivers of the United States are (1) the effects of dams and reservoirs on sedi- ment transport, (2) importance of large, infre- quent storms on the generation and transport of sediment, and (3) the implications of sedi- ment storage on the downstream movement of sediment particles and their associated contami- nants. Dams and reservoirs have diminished by one-half the amount of sediment that the Mis- sissippi River formerly transported to its delta. They have almost completely stopped the sea- ward transport of sediment by two other great rivers of the country, the Colorado and the Rio Grande. Until the storage of sediment in river valleys at different time scales is understood more clearly, predicting the fate of many of the pollutant substances that are found in the Nation's rivers will continue to be problem- atical. A. Juniata River at Newport, Pennsylvania B. Delaware River at Trenton, New Jersey COz o COz o C. Eel River at Scotia, California CJ cc 150-1 CO6 Q. CO 100- 50- EXPLANATION I. . In full I In 10 percent L .Inl percent f of year of year J J Storm of December, 1964 WATER YEAR Figure 33. Annual suspended-sediment discharge of three rivers showing the fre- quencies of suspended-sediment discharges within individual years and the importance of infrequent heavy storms in producing large sediment loads. A, Juniata River at Newport, Pa. B, Delaware River at Trenton, N.J. C, Eel River at Scotia, Calif. (Source: Compiled by R. H. Meade from U.S. Geological Survey daily-sediment data.) 60 National Water Summary 1984 Hydrologic Perspectives SELECTED REFERENCES Bopp, R. F., Simpson, H. J. Olsen, C. R. Trier, R. M., and Kostyk, Nadia, 1982, Chlorinated hydrocarbons and radionuclide chronologies in sediments of the Hudson river and estuary, New York: Environmental Science and Technology, v. 16, no. 10, p. 666-676. Brown, W. M., Ill, and Ritter, J. R., 1971, Sedi- ment transport and turbidity in the Eel River basin, California: U.S. Geological Survey Water-Supply Paper 1986, 70 p. Burrows, R. L., and Harrold, P. E., 1983, Sediment transport in the Tanana River near Fairbanks, Alaska, 1980-81: U.S. Geological Survey Water-Resources Investigations Report 83- 4046,116 p. Curtis, W. F., Culbertson, J. K., and Chase, E. B., 1973, Fluvial-sediment discharge to the oceans from the conterminous United States: U.S. Geological Survey Circular 670, 17 p. Emmett, W. W., Leopold, L. B., and Myrick, R. M., 1983, Some characteristics of fluvial processes in rivers, in International Symposium on River Sedimentation, 2d, Nanjing, China, October 11-16, 1983, Proceedings: Beijing, Water Resources and Electric Power Press, p. 730-754. Everett, D. E., 1971, Hydrologic and quality charac- teristics of the lower Mississippi River: Louisia- na Department of Public Works Technical Re- port 5, 48 p. Gilbert, G. K., 1917, Hydraulic-mining debris in the Sierra Nevada: U.S. Geological Survey Profes- sional Paper 105,154 p. Haeni, F. P., 1983, Sediment deposition in the Columbia and lower Cowlitz Rivers, Washing- ton-Oregon, caused by the May 18, 1980, erup- tion of Mount St. Helens: U.S. Geological Survey Circular 850-K, 21 p. Kelley, R. L., 1959, Gold vs. grain The hydraulic mining controversy in California's Sacramento Valley: Glendale, Calif., Arthur H. Clark, 327 p. Knott, J. M., and Lipscomb, S. W., 1983, Sediment discharge data for selected sites in the Susitna River basin, Alaska, 1981-82: U.S. Geological Survey Open-File Report 83-870, 45 p. Langbein, W. B., and Schumm, S. A., 1958, Yield of sediment in relation to mean annual precipi- tation: American Geophysical Union Transac- tions^. 39, p. 1076-1084. Lisle, T. E., 1981, The recovery of aggraded stream channels at gauging stations in northern California and southern Oregon, in Davies, T. R. H., and Pearce, A. J., eds., Erosion and sediment transport in Pacific Rim Steeplands: International Association of Hydrological Sciences Publication 132, p. 189-211. __1982, Effects of aggradation and degradation on riffle-pool morphology in natural gravel channels, northwestern California: Water Resources Research, v. 18, no. 6, p. 1643-1651. Meade, R. H., 1982, Sources, sinks, and storage of river sediment in the Atlantic drainage of the United States: Journal of Geology, v. 90, no. 3, p.235-252. Meade, R. H., Emmett, W. W., and Myrick, R. M., 1981, Movement and storage of bed material during 1979 in East Fork River, Wyoming, USA, i/i Davies, T. R. H., and Pearce, A. J., eds., Erosion and sediment transport in Pacific Rim Steeplands: International Association of Hydrological Sciences Publication 132, p. 225-235. Meade, R. H., Nordin, C. F., Jr., and Curtis, W. F., 1979, Sediment in Rio Amazonas and some of its principal tributaries during the high-water seasons of 1976 and 1977: Associacao Brasileira de Hidrologia e Recursos Hidricos, Simposio Brasileiro de Hidrologia, 3rd, Anais, v. 2, p. 472-485. Meade, R. H., Nordin, C. F., Jr., Perez-Hernandez, David, Mejia-B., Abel, and Perez-Godoy, J. M., 1983, Sediment and water discharge in Rio Orinoco, Venezuela and Colombia, in In- ternational Symposium on River Sedimenta- tion, 2d, Nanjing, China, October 11-16, 1983, Proceedings: Beijing, Water Resources and Electric Power Press, p. 1134-1144. Milliman, J. D., and Meade, R. H., 1983, World- wide delivery of river sediment to the oceans: Journal of Geology, v. 91, no. l,p. 1-21. Rainwater, F. H., 1962, Stream composition of the conterminous United States: U.S. Geological Survey Hydrologic Investigations Atlas HA-61. Scott, K. M., 1982, Erosion and sedimentation in the Kenai River, Alaska: U.S. Geological Survey Professional Paper 1235, 35 p. Trimble, S. W., 1983, A sediment budget for Coon Creek basin in the Driftless Area, Wisconsin, 1853-1977: American Journal of Science, v. 283, p. 454-474. Trimble, S. W., and Lund, S. W., 1982, Soil conser- vation and the reduction of erosion and sedimentation in the Coon Creek basin, Wis- consin: U.S. Geological Survey Professional Paper 1234,35 p. U.S. Geological Survey, 1984, National water sum- mary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. Walling, D. E., 1983, The sediment delivery prob- lem, in Rodriguez-Iturbe, Ignacio, and Gupta, V. K., eds., Scale problems in hydrology: Jour- nal of Hydrology, v. 65, p. 209-237. Wells, F. C., 1980, Hydrology and water quality of the lower Mississippi River: Louisiana Office of Public Works Technical Report 21, 83 p. Williams, G. P., and Wolman, M. G., 1984, Down- stream effects of dams on alluvial rivers: U.S. Geological Survey Professional Paper 1286, 83 p. Wischmeier, W. H., and Smith, D. D., 1965, Predicting rainfall-erosion losses from cropland east of the Rocky Mountains: U.S. Department of Agriculture, Agricultural Handbook 282, 47 p. National Water Summary 1984 Water-Quality Issues 61 LOADS AND CONCENTRATIONS OF DISSOLVED SOLIDS, PHOSPHORUS, AND INORGANIC NITROGEN AT U.S. GEOLOGICAL SURVEY NATIONAL STREAM QUALITY ACCOUNTING NETWORK STATIONS By James E. KIrcher, Robert J. Gil Horn, and R. Edward Hickman Dissolved solids, phosphorus, and nitrogen were identified as water-quality concerns in the 1983 National Water Summary (U.S. Geologi- cal Survey, 1984, p. 45-63). When present in high concentrations, they can restrict water use for many purposes. The following discussion provides a broad, national perspective of the loads (transport rates) and concentrations of dissolved solids, total phosphorus, and inor- ganic nitrogen (nitrate plus nitrite) in the Nation's major rivers and also serves as an introduction to subsequent discussions of water-quality trend analyses and case studies of dissolved solids in the Colorado and Arkansas Rivers. DATA SOURCES AND METHODS Data used in this discussion and in the following trend analyses are from the U.S. Geological Survey's National Stream Quality Accounting Network (NASQAN). This network was established in 1972 to account for the quantity and quality of streamflow within the United States, to depict the areal variability of water conditions, and to detect changes in stream quality with time (Britton and others, 1983, p. 5). Data collected include the quantity of streamflow, concentrations of major inor- ganic and trace constituents, presence or ab- sence of bacterial indicators of pollution, and concentrations of selected pesticides. A stand- ard set of water-quality characteristics is mea- sured at each station using the same collecting procedures, sampling frequency, and analytical methods. These procedures provide uniform and consistent data upon which to base analy- ses. NASQAN is an "accounting network" in that it measures the amount of water and dissolved or suspended material that move from one hydrologic accounting unit to another or to the oceans. However, the data from NASQAN sta- tions do not necessarily characterize water- quality conditions either upstream or down- stream of the measuring points because many of the reported constituents undergo changes in concentrations as the water moves downstream. Of 504 currently active NASQAN stations, the 298 stations with complete monthly data from October 1974 to September 1981 (water years 1975-81) were selected to depict national pat- terns of mean concentrations and transport. Concentration of a constituent usually is ex- pressed as mass per unit volume of water and is reported here as milligrams per liter. Transport is characterized by the mean annual load of a constituent passing by a station. It is computed as the product of water discharge and concen- tration and is reported as tons per day or tons per year. In this report, mean annual loads and mean annual concentrations were calculated using methods described by Smith and Alex- ander (1983). All results are shown on national maps (figs. 34, 35, and 36). The mean annual load at each station is shown by a circle that is propor- tional in size to the computed load, as indicated in the map explanations. All loads less than the minimum amount specified in the map explana- tions are depicted by the same-sized circle. Concentrations of each constituent are general- ized in three classes and indicated by the color of the circle. DISSOLVED SOLIDS The major inorganic components of dis- solved solids in rivers are sodium, potassium, calcium, magnesium, carbonate, bicarbonate, chloride, and sulfate ions (Rainwater, 1962). The main sources of these constituents are the dissolution of rock and soil, atmospheric depo- sition, and human activities. Human activities contribute dissolved solids through the dis- charge of wastewater from such point sources as municipal and industrial waste treatment plants and through runoff and drainage from such nonpoint sources as agricultural and ur- ban areas. One of the most important sources of dissolved solids is irrigation return flow to streams by direct surface runoff or by subsur- face drainage. Agricultural and natural sources of dissolved solids are addressed in more detail later in this report in the case studies of dis- 62 National Water Summary 1984 Hydrologic Perspectives Figure 34. Dissolved-solids loads (tons per year) and mean annual concentra- tions (milligrams per liter) at U.S. Geological Survey National Stream Quality Accounting Network sta- tions in the conterminous United States, 1975 to 1981. Color of the circle repre- sents the concentration range and the size of the circle is proportional to the load. (Source: Compiled from data in Smith and Alexander, 1983.) solved solids in the Colorado and Arkansas River basins. The importance of atmospheric sources, which include both human-induced and natural dissolved solids, was evaluated by Peters (1984). The concentration of dissolved solids is used widely as a general indicator of water quality and of the suitability of water for vari- ous uses. High concentrations, for example, hamper municipal and industrial uses of water by increasing treatment costs, accelerating pipe corrosion, and increasing soap and detergent use. The U.S. Environmental Protection Agency (1982a) recommends that public water supplies contain no more than 500 milligrams per liter (mg/L) of dissolved solids. High dis- solved solids also detract from the value of water for irrigation at levels greater than about 700 mg/L (U.S. Bureau of Reclamation, 1983) although higher concentrations can be tolerated by some crops grown on permeable soils with careful water irrigation management. General- ly, water used for irrigation contains less than 2,000 mg/L (National Academy of Sciences and National Academy of Engineering, 1972, p. 335). The mass transport of dissolved solids by a river is sometimes used as a measure of how rapidly rock weathering is occurring in a watershed. Mean dissolved-solids concentrations at NASQAN stations vary widely, reflecting the broad range of natural and human influences on dissolved solids in different parts of the country (fig. 34). Mean concentrations at NASQAN stations range from 26.0 mg/L in the Saco River in Maine to 32,900 mg/L in the Salt Fork Brazos River in Texas. These extremes are indicative of the general pattern of more high concentrations west of the Mississippi River than to the east. Of 71 stations with mean concentrations exceeding the drinking water criteria of 500 mg/L, 68 are west of the Mississippi River. The western part of the country contains vast arid and semiarid areas that favor concentration of dissolved solids through evapotranspiration, a process further stimulated by extensive irrigation. In areas with moderate to high annual precipitation mainly the area east of the Mississippi River, mountain areas, and the Pacific Northwest rivers generally have low dissolved-solids con- centrations due to dilution. EXPLANATION Dissolved solids Load, in tons per year Less than 100,000 10,000,000 100,000,000 Concentration, in milligrams per liter 0 o-ioo 0 100-500 flfc Greater than 500 National Water Summary 1984 Water-Quality Issues 63 In contrast to dissolved-solids concentra- tion, the greatest transport of dissolved solids occurs in rivers with the largest flows of water even though they contain fairly low concentra- tions (fig. 34). The prominent example is the Mississippi River, which transports an average of about 121 million tons per year into the Gulf of Mexico. The Mississippi and other large rivers carrying particularly high dissolved- solids loads the St. Lawrence, the Ohio, and the lower Missouri generally drain large hu- mid areas of the Nation with relatively high rates of rock weathering, extensive agriculture, and high population densities. In most rivers, dissolved-solids loads generally increase down- stream as the flow of the river increases. PHOSPHORUS Phosphorus is an essential and key plant nutrient derived from natural and human- induced sources. Most phosphorus in rivers is either dissolved as phosphate ions and organic phosphorus molecules or suspended in associa- tion with inorganic suspended sediment and organic particulate matter, such as algae. Natural sources of phosphorus include dissolu- tion of phosphorus-bearing rocks (abundant in some parts of the country, such as Florida), decay of organic plant material, animal wastes, and atmospheric deposition. Important human-induced sources are human wastes and synthetic detergents in sewage effluent and runoff from feedlots and urban and fertilizer- rich agricultural areas. The principal adverse effect of phosphorus on water quality is the stimulation of excessive growth of aquatic plants. Such growth may lead to murky water, floating scums of algae, dense mats of rooted and floating aquatic plants, depletion of dissolved oxygen associated with decaying plant material, and associated damage to fisheries. Recreation may be ham- pered and treatment costs may increase for municipal and industrial users. Such problems are more severe in lakes, reservoirs, and estu- aries fed by rivers rather than within the rivers, where velocities of flow reduce the adverse effects. The U.S. Environmental Protection Agency (1976) has suggested that total phos- phorus concentrations generally should not exceed 0.05 mg/L in rivers near where they enter a lake or reservoir or 0.10 mg/L elsewhere Figure 35. Phosphorus loads (tons per year) and mean annual concentrations (mil- ligrams per liter) at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981. Color of the circle represents the concentration range and the size of the circle is pro- portional to the load. (Source: Compiled from data in Smith and Alexan- der, 1983.) Concentration, in milligrams per liter 64 National Water Summary 1984 Hydrologic Perspectives Figure 36. Inorganic nitrogen (nitrate plus nitrite) loads (tons per year) and mean annual concentrations (mil- ligrams per liter) at U.S. Geological Survey National Stream Quality Accounting Network stations in the conterminous United States, 1975 to 1981. Color of the circle represents the concentration range and the size of the circle is pro- portional to the load. (Source: Compiled from data in Smith and Alexan- der, 1983.) in rivers. However, the variability between rivers in terms of the biological availability of the phosphorus they contain is so large that uniform criteria are often not suitable or rele- vant, and, thus, there is no firm total phos- phorus criterion. The load of phosphorus carried by a river is particularly important where it enters a lake, reservoir, or estuary. Useful management criteria have been developed from relations between phosphorus loadings to lakes and reservoirs and phosphorus concentrations in the impoundments (for example, see Reckow, 1979). However, the applicability of such rela- tions to river inflows carrying much of the phosphorus in association with inorganic par- ticulate matter, rather than in more biologically available forms, is unclear. Mean concentrations of total phosphorus at NASQAN stations vary widely across the coun- try (fig. 35) and generally are similar in pattern to the suspended-sediment concentrations depicted in figure 25 (see "Sediment in the Rivers of the United States"). In many rivers, most of the phosphorus is associated with fine- grained sediment rather than with the dissolved state. Mean concentrations range from 0.015 mg/L in the Saco River in Maine to 5.7 mg/L in the Little Colorado River in Arizona. The general quality guideline of 0.05 mg/L for rivers entering lakes or reservoirs is exceeded by mean concentrations at 233 stations, and the guideline of 0.10 mg/L is exceeded at 165 sta- tions. The high frequency at which the quality guidelines are exceeded may be somewhat mis- leading because a majority of the phosphorus in these large rivers probably is bound tightly with sediment particles and not readily available to biota. As with dissolved solids, most phosphorus transport occurs where flow is greatest, even though concentrations are moderate. The greatest loads occur in the Mississippi River basin where flows are large and in which many of the tributaries drain agricultural land and, therefore, have high concentrations of the nu- trient. INORGANIC NITROGEN Like phosphorus, nitrogen also is a key plant nutrient. The primary forms of nitrogen in rivers are nitrate, nitrite, ammonia, and EXPLANATION Inorganic nitrogen (nitrate plus nitrite) Load, in tons per year Less than 100 50,000 1.000,000 Concentration, in milligrams per liter 0 0.0-0.5 0.5-1.0 Greater than 1.0 National Water Summary 1984 Water-Quality Issues 65 assorted organic compounds. This discussion focuses on inorganic nitrogen which primarily consists of nitrate with lesser amounts of ni- trite. The principal natural sources of nitrogen are atmospheric deposition and soil nitrogen derived from the degradation of organic material and biological fixation of nitrogen gas from the atmosphere. Human sources include sewage effluent and agricultural and urban run- off. The various transformations of nitrogen compounds in the environment are discussed in detail in the article "Overview of the Occur- rence of Nitrate in Ground Water of the United States." Nitrate is much more soluble than phosphorus, and all nitrate found in river water is biologically available. Potential water-quality effects of nitrate include stimulation of excessive plant growth and toxicity to human infants. There are no water-quality criteria related to the role of nitrogen in stimulating plant growth. The human-health criterion for nitrate in drinking- water supplies is 10 mg/L as nitrogen (U.S. Environmental Protection Agency, 1982b). Nitrate concentrations follow a pattern that is distinctly different from that of dis- solved solids and phosphorus (fig. 36). Many of the highest mean concentrations are in the Mississippi River and its tributaries where dis- charge and transport also are high. Much of that area is farmed intensely, receives heavy nitrogen fertilizer applications, and produces large quantities of nitrogen-rich livestock wastes. Nationwide, mean nitrate concentra- tions range from 0.025 mg/L nitrogen in the Pend Oreille River in Washington to 9.8 mg/L nitrogen in the Gila River in Arizona. Mean nitrate concentration did not exceed the human-health criterion of 10 mg/L at any station. The foregoing national scale analysis of mean concentrations and loads of three key water-quality constituents provides an overview of recent average conditions in the Nation's larger rivers. This overview may be compared with the discussion of recent trends for the same constituents, which is covered in more detail in the following article. SELECTED REFERENCES Britton, L. J., Goddard, K. E., and Briggs, J. C., 1983, Quality of rivers of the United States, 1976 water year Based on the National Stream Quality Accounting Network (NASQAN): U.S. Geological Survey, Open-File Report 80-594, 423 p. National Academy of Sciences and National Acade- my of Engineering, 1972 [1974], Water quality criteria 1972: Washington, D.C., U.S. Govern- ment Printing Office, 594 p. Peters, N. E., 1984, An evaluation of environmental factors affecting major dissolved ion yields of streams in the United States: U.S. Geological Survey Water-Supply Paper 2228,44 p. Rainwater, F. H., 1962, Stream composition of the conterminous United States: U.S. Geological Survey Hydrologic Investigations Atlas HA-61. Reckow, K. H., 1979, Quantitative techniques for the assessment of lake quality: U.S. Environ- mental Protection Agency, Report no. EPA- 440/5-79-015, 145 p. Smith, R. A., and Alexander, R. B., 1983, A statisti- cal summary of data from the U.S. Geological Survey's national water quality networks: U.S. Geological Survey Open-File Report 83-533, 28 p. U.S. Bureau of Reclamation, 1983, Status report Colorado River water-quality improvement pro- gram: Denver, Colorado, 126 p. U.S. Environmental Protection Agency, 1976, Qual- ity criteria for water: Washington, D.C., U.S. Government Printing Office, 256 p. __1980, Economic benefits of the clean lakes pro- gram: U.S. Environmental Protection Agency, Report no. EPA-440/5-80-081, 121 p. __1982a, Secondary maximum contaminant levels (Section 143.3 of part 143, National secondary drinking-water regulations): U.S. Code of Fed- eral Regulations, Title 40, Parts 100-149, re- vised as of July 1,1982, p. 374. __1982b, Maximum contaminant levels (subpart B of part 141, National interim primary drinking- water regulations): U.S. Code of Federal Regu- lations, Title 40, parts 100-149, revised as of July 1,1982, p. 315-318. __1984a, National water quality inventory, 1982 report to Congress: U.S. Environmental Protec- tion Agency, Report no. EPA 440/2-84-006, 63 p. __1984b, Report to Congress Nonpoint source pollution in the U.S.: Washington, D.C., U.S. Environmental Protection Agency, Office of Water Program Operations, Water Planning Division, p. 1-1-4-15. U.S. Geological Survey, 1984, National Water Sum- mary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. 66 National Water Summary 1984 Hydrologic Perspectives TRENDS IN CONCENTRATIONS OF DISSOLVED SOLIDS, SUSPENDED SEDIMENTS, PHOSPHORUS, AND INORGANIC NITROGEN AT U.S. GEOLOGICAL SURVEY NATIONAL STREAM QUALITY ACCOUNTING NETWORK STATIONS By Richard A. Smith and Richard B. Alexander The U.S. Geological Survey is analyzing and interpreting trends in data at its National Stream Quality Accounting Network (NASQAN) and National Hydrologic Bench-Mark Network of water-quality monitoring stations using statistical trend-testing procedures (Hirsch and others, 1982; Smith and others, 1982) and ancillary information from large environmental data bases such as the National Resource Inven- tory (U.S. Department of Agriculture, 1984). The 1983 National Water Summary (U.S. Geo- logical Survey, 1984, p. 46) included prelimi- nary results of these trend analyses for a group of 34 water-quality constituents. This article presents the national pattern of trends for dissolved solids, suspended sediment, total phosphorus, and inorganic nitrogen (nitrate plus nitrite) based on data collected at 298 NASQAN stations between October 1974 and September 1981 (water years 1975-81) and proposes possible explanations for their occur- rence. Because the purpose of these analyses is to define water-quality trends resulting from hu- man activity rather than from natural causes such as changes in temperature and precipita- tion, the statistical trend testing procedures have been designed to remove variations in water quality resulting from changes in season and streamflow. Each trend was tested for significance at the 90-percent confidence level which implies that there is less than a 10-percent chance that the trend could have resulted from a random arrangement of the data. In the following maps, which are used to illustrate the trend patterns, triangles indicate the location of stations with trends that are statistically signifi- cant, and circles indicate the location of sta- tions where trends are not significant (concen- trations are interpreted to have not changed). Upward-pointing triangles indicate increasing concentrations, and downward-pointing trian- gles indicate decreasing concentrations. TRENDS IN DISSOLVED SOLIDS A large number of the Nation's rivers showed significant change in dissolved solids during water years 1975 to 1981 (fig. 37). Dissolved-solids concentrations increased at 59 percent of the stations that showed significant trends. Because the data were flow adjusted before applying the trend tests, the effects of wet and dry years largely were eliminated as explanations for these trends. Therefore, some form of human activity is the probable cause for most of the trends. The geographic pattern of the trends and the location of irrigated farmlands suggests that irrigation return flows are important contribu- tors of dissolved material to rivers, especially in semiarid basins of the West and Southwest. Increases in irrigated agriculture in some basins may lead to increases in dissolved solids. In basins where efforts to control the dissolved- solids content (salinity) of return flows have been made, dissolved-solids concentrations may decrease over time. River basins in which irrigated agriculture is thought to have a major influence on water quality include the Arkan- sas, Red, and Colorado to name a few. (See case study articles "Dissolved Solids in the Colorado River Basin" and "Dissolved Solids in the Arkansas River Basin.") A second type of human activity that may influence dissolved-solids trends is the applica- tion of salt to highways for snow and ice control. Highway salt application has increased dramatically in quantity and geographic extent since the 1950's and is now a major source of dissolved salt in river basins in the Northeast and North-Central States as far south as Mis- souri and Virginia. Since 1974, however, the nationwide tonnage of applied salt has fluctuat- ed considerably from year to year in response to the severity of winter weather (fig. 38). More- over, changes in the use of highway salt may lead to either increasing or decreasing trends in dissolved solids, depending on the geographic region and the intensity of application in rela- tion to station locations. Further insight into the interpretation of these trends in dissolved solids will require analyses of individual basins. TRENDS IN SUSPENDED SEDIMENT Suspended-sediment trends from 1975 to 1981 show nearly equal numbers of stations with increasing (44) and decreasing (43) concen- trations, but some regional groupings of trends National Water Summary 1984 Water-Quality Issues 67 EXPLANATION Dissolved-solids concentration Symbol represents trend that is significant at the 90-percent confidence level (less than a 10-percent chance that the trend could have resulted from a random arrangement of the data) A Increasing trend \J Decreasing trend No change X No data Figure 37. Trends in dissolved-solids concentra- tions at U.S. Geological Survey National Stream Quality Accounting Network stations in the con- terminous United States, 1975 to 1981 (Source: Compiled from data in Smith and Alexander, 1983.) Figure 38. Increase of salt application as a highway deicing chemical in the United States, 1947 to 1983. (Source: Compiled by I. C. James II, U.S. Geological Survey, from data supplied by the Salt Institute, 1984.) 13 12 10 nnnnnnn 1947 1950 1955 1960 1965 1970 YEAR OF APPLICATION 1975 1980 1983 68 National Water Summary 1984 Hydrologic Perspectives EXPLANATION Suspended-sediment concentration Symbol represents trend that is significant at the 90-percent confidence level (less than a 10-percent chance that the trend could have resulted from a random arrangement of the data) A Increasing trend W Decreasing trend No change X No data Figure 39. Trends in suspend- ed-sediment concentra- tions at U.S. Geological Survey National Stream Quality Accounting Net- work stations in the conter- minous United States, 1975 to 1981. (Source: Compiled from data in Smith and Alexander, 1983.) are important (fig. 39); for example, a number of decreases in suspended-sediment concentra- tions occur on the Missouri River mainstem as well as on such tributaries as the Yellowstone, the Knife, the Cannonball, the Grand, the Bell Fourche, the White, and the James in Mon- tana, North Dakota, and South Dakota. De- clining concentrations have been reported previously for a number of locations in the Missouri River basin (Williams and Wolman, 1984) (see also article "Sediment in Rivers of the United States") and are attributed to the effects of reservoir construction throughout the basin during the 1950's and 1960's. Reservoirs act as a trap for sediment, and the effects of a reservoir on suspended-sediment concentra- tions downstream may be felt for an extended period of time after construction as a new equilibrium is established between those processes that carry sediment and those that result in sediment deposition in the river chan- nel. Regions in which the trends in suspended- sediment concentrations are mostly increasing include the Columbia River basin in Oregon and Washington, the Arkansas and Red River basins in Oklahoma, and the tributaries to the Mississippi River near the junctions of the Missouri and Ohio Rivers (fig. 39). In each instance, it appears likely that increased land use is an important cause of the trends; for example, in the Arkansas, Red, and Mississippi River basins, agricultural production increased during the late 1970's (U.S. Department of Percentage of drainage area located upstream of reservoirs Number of NASQAN stations showing trends in suspended-sediment concentrations Increasing Decreasing No change Less than 10 - - 10 to 50- - - - Greater than 50 27 6 10 29 6 4 136 26 32 National Water Summary 1984 Water-Quality Issues 69 Agriculture, 1983), and, in the Columbia River basin, logging increased during that period (U.S. Bureau of Census, 1984). In addition to the effects of land use, many streams in the Columbia River basin were transporting unusu- ally large loads of sediment derived from vol- canic ash and mudflow deposits resulting from eruptions of Mount St. Helens during 1980 and 1981 (Haeni, 1983). In addition to recognizing the regional patterns of trends visible in figure 39, some general questions about the possible trends in suspended-sediment concentrations in rivers throughout the country should be posed. In view of the large number of decreasing concen- trations in suspended sediment in the Missouri River basin, for example, it is logical to ques- tion the effect of reservoirs on sediment trends at NASQAN stations in general. The table to the left shows the number of stations with in- creasing, decreasing, and no significant change in concentrations as a function of the percent- age of basin area located upstream of reser- voirs. From this tabulation, it does not appear that the presence of reservoirs in the basin strongly correlates with the occurrence of suspended-sediment concentration trends in general. However, where more than 50 percent of the basin is controlled by reservoirs, a slight- ly greater percentage of stations have increasing concentrations than those in less controlled basins. The degree to which land use and related soil erosion affects trends in suspended- sediment concentrations at NASQAN stations also is an important question that has not yet been resolved. It is increasingly apparent that the off-site effects of soil erosion are extremely large in dollar terms, larger even than the effects of soil loss on agricultural production (Clark and others, 1985). It is of interest to know, therefore, whether NASQAN stations that conducted by the U.S. Soil Conservation Ser- vice (U.S. Department of Agriculture, 1984). The 1982 NRI includes soil-erosion estimates and related land use information for nearly 1 mil- lion sample locations across the country. The erosion data for individual sample locations can be aggregated according to the boundaries of the NASQAN river basins (a median of 2,037 NRI sites per basin) and then used to character- ize basins in which water-quality trends were observed during the same period. Some of the results of these comparisons appear below. Due to the possibility that intensive regulation by reservoirs may affect the trend results, the following analyses are based on NASQAN stations in basins with less than 50 percent of the drain- age area controlled by reservoirs. The table below gives the number of sta- tions at which suspended-sediment concentra- tion trends were detected in relation to cropland erosion rates in the basins. Where cropland erosion rate is low [less than 1 ton per acre per year (ton/acre/yr)], the number of decreasing trends is more than twice the number of in- creasing trends, and, where cropland erosion is high (greater than 5 ton/acre/yr), the ratio of decreases to increases is nearly reversed. The statistical significance of the associa- tion between trends in suspended-sediment con- centrations with erosion rates can be evaluated with the Chi-square test of independence. Chi- square tests can be performed on any relevant part of the tables presented in this section; for example, a Chi-square test comparing the num- bers of stations with increases and decreases in sediment concentrations in basins that have erosion rates less than 1 ton/acre/yr with those in basins having erosion rates greater than 5 ton/acre/yr, shows that the results are signifi- cant at the 90-percent confidence level (p = 0.07). The probability, p, of incorrectly reject- ing the null hypothesis that there is no associa- tion between concentration trends and erosion Cropland erosion rate (ton/acre/yr) Number of NASQAN stations showing trends in suspended-sediment concentrations Increasing Decreasing No change Less than 1 - 1 to 2.5 - - - 2.5 to 5 - - - Greater than 5 11 9 11 10 9 5 38 43 33 43 show increasing concentrations in suspended sediment lie downstream of areas of intense soil erosion and whether erosion resulting from specific types of land use is associated with the trends. The largest and most comprehensive collec- tion of information about soil erosion nation- wide is the Natural Resources Inventory (NRI) rates is equal to 0.07; therefore, the likelihood that the identified trend is real and does not result from a random arrangement of the data is 93 percent. This is above the 90-percent criterion, and, thus, the association is consid- ered significant at that level. This tends to support the conclusion that the direction of trends in suspended-sediment concentration is 70 National Water Summary 1984 Hydrologic Perspectives Erosion from rural land, as a percentage of total erosion Number of NASQAN stations showing trends in suspended-sediment concentrations Increasing Decreasing No change Cropland: Less than 25 - - - - - Greater than 25 - - - Forest land: Less than 25 - - - - - Greater than 25 - - - Range and pasture land: Less than 25 - - - - - Greater than 25 - - - 25 27 6 22 11 21 14 23 12 21 14 58 99 130 27 69 associated with the cropland erosion rate in the basin. If cropland erosion is expressed as a per- centage of total erosion in the basin, an even stronger relation is seen. As shown in the table above , decreases greatly outnumber increases where cropland erosion is a minor contributor to total erosion, but increases outnumber de- creases where cropland erosion contributes more than 25 percent of total erosion. A Chi- square test of dependence for the above ratios of increases to decreases is highly significant (p = 0.007). Trends in suspended-sediment concentra- tions vary in relation to erosion from other types of rural land, such as range and forest lands, in a fashion complementary to the pat- tern described above for cropland. As shown in the table above, decreases outnumber increases where either forest land or range and pasture land contribute more than 25 percent of total soil erosion in the basin; however, the results are not significant at the 90-percent level (p = 0.13 for forest land; p = 0.56 for range and pasture land). Thus, despite certain regional exceptions to the pattern, evidence exists that, on a nation- wide scale, the hydrologic effects of cropland erosion represent a worsening problem, and those of erosion from other types of land apparently do not. This result, if borne out in more focused types of sampling programs, would have important policy implications re- garding the allocation of erosion control ef- forts. For the present, however, it remains a tentative finding with implications primarily for future sampling and analysis. TRENDS IN PHOSPHORUS CONCENTRATIONS Total phosphorus concentrations at NASQAN stations for water years 1975 to 1981 show roughly equal numbers of increasing (49) and decreasing (43) trends in phosphorus nation- wide (fig. 40), but, as with suspended-sediment concentrations, certain regions exist in which the trends are predominantly in one or the other direction. In the Great Lakes and Upper Mis- sissippi regions, phosphorus concentrations generally are declining possibly as a result of major phosphorus-control efforts in those areas during the late 1970's (Loehr and others, 1980). In Florida, along the Gulf Coast, and in the Arkansas and Red River basins, phos- phorus concentrations are mostly increasing. Many of the increases in the South are in agricultural areas and, thus, may result from increased agricultural activity and fertilizer use. The geographic distribution of trends in phosphorus and suspended-sediment concen- trations are similar, a finding that is not supris- ing because of the tendency for phosphorus to adsorb to the surface of sediment particles. The relation between trends in phosphorus and suspended-sediment concentrations is summa- rized in the table below. The results of a Chi-square test are highly significant (p = 0.001). Direction of trend in phosphorus concentrations Increasing 12 - - 1 31 Number of NASQAN stations showing trends in suspended-sediment concentrations Decreasing No change *- &J 9 19 30 161 Major source of soil erosion in river basins Number of NASQAN stations showing trends ____in phosphorus concentrations____ Increasing Decreasing No change Cropland ------ Range and pasture land Forest and other lands- 13 11 6 14 3 7 73 62 46 National Water Summary 1984 Water-Quality Issues 71 ' * '\ ' f TA. i --*> EXPLANATION Phosphorus concentration Symbol represents trend that is significant at the 90-percent confidence level (less than a 10-percent chance that the trend could have resulted from a random arrangement of the data) Increasing trend W Decreasing trend * No change X No data Some apparent differences, however, exist between the trends in phosphorus and suspended-sediment concentrations in terms of their relation to land use and soil erosion within a basin. Basins where the total erosion is dominated by erosion from pasture and range land have a noticeably higher ratio of phos- phorus increases to decreases than basins where total erosion is dominated by erosion from either cropland or forest and other nonagricul- tural lands (see table to the left ) However, the association between concentration trends and major source of soil erosion is not quite signifi- cant at the 90-percent level (p = 0.13). TRENDS IN INORGANIC NITROGEN (NITRATE PLUS NITRITE) CONCENTRATIONS Inorganic nitrogen concentrations at NASQAN stations from 1975 to 1981 show a large number of increases nationwide, especially at stations in the eastern one-half of the country and in the Pacific coast basins of the North- west. Only scattered locations in the western one-half of the country, especially the Colora- do River basin, show decreases (fig. 41). Although the ratio of increases to decreases for inorganic nitrogen is about 3 to 1 nation- wide, the ratio varies greatly with the type of land and the erosion rate. This suggests that nonpoint sources of inorganic nitrogen are involved to some extent, which is not surprising in view of the importance of nitrogen fertilizers in agriculture generally. Trends in inorganic nitrogen in relation to the type of land con- tributing the largest percentage of total soil erosion in a basin are shown in the table below. These trends show a much lower ratio of increases to decreases for basins dominated by Major source of soil erosion in river basins Range and pasture land - - - Forest and other lands- - - - Number of NASQAN stations showing trends in inorganic nitrogen concentrations Increasing Decreasing No change 33 4 63 9 11 56 19 3 39 Ratio of increases to decreases 8 T« .82 6.00 Figure 40. Trends in total phosphorus concentra- tions at U.S. Geological Survey National Stream Quality Accounting Net- work stations in the conter- minous United States, 1975 to 1981. (Source: Compiled from data in Smith and Alexander, 1983.) 72 National Water Summary 1984 Hydrologic Perspectives Figure 41. Trends in inorganic nitrogen (nitrate plus ni- trite) concentrations at sta- tions in the U.S. Geological Survey National Stream Quality Accounting Net- work stations in the conter- minous United States, 1975 to 1981. (Source: Compiled from data in Smith and Alexander, 1983.) erosion from range and pasture land than for basins dominated by erosion from either crop- land or forest and other nonagriculture lands. Differences in the trend ratios for the three types of land use are highly significant (p = 0.0004). From 1975 to 1981, the total quantity of nitrogen fertilizer applied nationally in- creased by about 38 percent (U.S. Bureau of Census, 1984), a change which would tend to explain the high number of increases for crop- land-dominated basins. The relatively large number of increases in inorganic nitrogen concentrations at NASQAN stations result, at least in part, from widespread increases in atmospheric deposition of nitrate rather than from changes in nitrogen sources directly from the land. The primary evidence for the important role of atmospheric sources consists of recently available nationwide meas- urements of nitrate in precipitation (J. H. Gib- son and C. V. Baker, National Atmospheric Deposition Program, written commun., 1982), which correlate well with inorganic nitrogen levels at NASQAN stations and represent, in some instances, the largest known source of nitrogen in the basin. Moreover, emission rates of nitro- gen to the atmosphere are known to have increased since 1975, especially in the Eastern States (National Research Council, 1983). Median yields of inorganic nitrogen at NASQAN stations (quantity of inorganic nitrogen carried by a stream per year per unit area of drainage basin) in relation to the atmospheric deposition rate of nitrate in precipitation is shown in figure 42 for each of the 18 water- resources regions of the conterminous United States. In the eastern basins, nitrate deposition ranges from one to three times the basin yield of nitrate; and, in the western basins, with the exception of the California region, atmospheric deposition is as high as 10 times basin yield. By comparison, point sources of nitrogen amount to only about one-half to one-third of the measured yield in most of the water-resources regions (Leonard Gianessi, Resources for the Future, written commun., 1984). In regions dominated by cropland, nitrogen-fertilizer ap- plication equals from 5 to 10 times the basin yield of nitrate. Because inorganic nitrogen is a plant nutri- ent and is biologically removable from soil and water, it is not surprising that the total of all EXPLANATION Inorganic nitrogen (nitrate plus nitrite) concentration Symbol represents trend that is significant at the 90-percent confidence level (Jess than a 10-percent chance that the trend could have resulted from a random arrangement of the data) A Increasing trend y Decreasing trend No change X No data National Water Summary 1984 Water-Quality Issues 73 sources of nitrogen is greater than the basin yield of inorganic nitrogen in these large re- gions. Given the data currently available, however, it is nearly impossible to develop a complete mass balance for nitrogen; that is, accurately quantify all inputs and outputs. For this reason, some uncertainty remains about the causes for trends in inorganic nitrogen in stream water. 6.0 50 cc 4.0 ^ 2.0 1.0 ohio / V Mid-Atlantic XTennessee Californ a Pacific Northwest Grea/Baglp.^ x 4 K , Rio Grande i / X Lower /Mississippi Upper Mississippi * $ New England Great Lakes South Atlantic-Gulf Colorado (Upper and Lower) X^Souris-Red-Rasny / _^-<» Texas-Gulf Missouri ^Arkahsas-Whlte-Red 0 1.0 2.0 3.0 4.0 5.0 DEPOSITION, IN POUNDS PER ACRE PER YEAR 6.0 Figure 42. Median yield of inorganic nitrogen at U.S. Geological Survey National Stream Quality Ac- counting Network stations in relation to atmos- pheric deposition rate of nitrate in precipitation for the 18 water-resources regions of the contermi- nous United States. (Source: Compiled by R. A. Smith and R. B. Alexander from U.S. Geological Survey data.) SELECTED REFERENCES Clark, E. H., Haverkamp, J. A., and Chapman, W., 1985, Eroding soils The off-farm impacts of soil erosion: Washington, D.C., The Conserva- tion Foundation. Haeni, F. P., 1983, Sediment deposition in the Columbia and lower Cowlitz Rivers, Washing- ton-Oregon, caused by the May 18, 1980, erup- tion of Mount St. Helens: U.S. Geological Survey Circular 850-K, 21 p. Hirsch, R. M., Slack, J. R., and Smith, R. A., 1982, Techniques of trend analysis for monthly water-quality data: Water Resources Research, v. 18, no. 1, p. 107-121. Loehr, R. C., Martin, C. S., and Rast, W., eds, 1980, Phosphorous management strategies for lakes: Ann Arbor, Mich., Ann Arbor Science Publishers, Inc., 490 p. National Research Council, 1983, Acid deposi- tion Atmospheric processes in eastern North America: Washington, D.C., National Acade- my Press, 375 p. Smith, R. A., and Alexander, R. B., 1983, A statisti- cal summary of data from the U.S. Geological Survey's national water quality networks: U.S. Geological Survey Open-File Report 83-533, 30 p. Smith, R. A., Hirsch, R. M., and Slack, J. R., 1982, A study of trends in total phosphorus measure- ments at NASQAN stations: U.S. Geological Sur- vey Water-Supply Paper 2190, 34 p. U.S. Bureau of Census, 1984, Statistical abstracts of the United States 1984: Washington, D.C. U.S. Governmnet Printing Office, 1015 p. U.S. Department of Agriculture, 1983, 1983 Hand- book of agricultural charts: Agricultural Hand- book No. 619,96 p. __1984, National resources inventory A guide for users of the 1982 NRI data files: Washington, D.C., U.S. Soil Conservation Service and Iowa State University, 32 p. U.S. Geological Survey, 1984, National water sum- mary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. Williams, G. P., and Wolman, M. G., 1984, Down- stream effects of dams on alluvial rivers: U.S. Geological Survey Professional Paper 1286, 83 p. 74 National Water Summary 1984 Hydrologic Perspectives Dissolved Solids Case Studies DISSOLVED SOLIDS IN THE COLORADO RIVER BASIN By James E. Kircher 1% "Municipal Exports and industrial Figure 43. Source of dis- solved solids in the Colo- rado River basin. (Source: Modified from Jonez, 1984, p. 338.) INTRODUCTION The Colorado River is an important source of water for more than 14!/2 million people, many industrial users, and about 2'/2 million acres of irrigated agricultural land. As the Colorado River and its tributaries flow from their headwaters to their mouths, the concen- trations of dissolved solids increase to undesira- ble levels, which result in millions of dollars of damage annually to agricultural, industrial, and municipal water users (U.S. Bureau of Reclamation, 1983a). The cost attributed to excessive dissolved solids in the Colorado River system was about $91 million in 1983 (D. H. Merritt, U.S. Bureau of Reclamation, written commun., 1984). The effects on municipal and industrial users occur primarily as increased water- treatment costs, accelerated pipe corrosion and appliance wear, increased usage of soap and detergent, and decreased water palatability. For irrigators, the greater dissolved-solids concen- trations cause decreased crop yields, altered crop patterns, increased soil leaching and drain- age requirements, and increased management costs. Depending on the soil conditions, the composition of dissolved solids in the water, and the type of crop, agricultural losses occur when dissolved-solids concentrations of applied irrigation water reach 700 to 850 milligrams per liter (mg/L). The 1,400-mile (mi)-long Colorado River originates in the Rocky Mountains of Colorado and is joined by its principal tributary, the Green River, which originates in Wyoming. The Colorado River and its tributaries drain 242,000 square miles (mi2), including parts of seven States Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming, or one-twelfth of the conterminous United States and 2,000 mi2 in Mexico. Precipitation in the Colorado River basin ranges from as much as 60 inches per year (in./yr) in the mountains to as little as 2 in./yr in the deserts adjacent to the middle and lower reaches. The range in precipitation and natural wet- and dry-climatic cycles have affected sig- nificantly the development of the Colorado River reservoir complex. Many dams and reser- voirs exist along the Colorado River in order to store sufficient water to maintain flows of the Colorado River to meet downstream needs during dry periods. In fact, the many reservoirs in the Colorado River basin can store amounts of water equivalent to the average flow of the Colorado River for several years (U.S. Geologi- cal Survey, 1984, p. 32). SOURCE OF DISSOLVED SOLIDS The dissolved-solids concentration of the Colorado River at its headwaters in the moun- tains is about 50 mg/L. This amount increases progressively downstream as a result of water use and dissolved-solids contributions from a variety of sources and reaches an average con- centration of about 850 mg/L at Imperial Dam, Ariz. About one-half of the dissolved-solids concentration in the Colorado River basin is attributed to natural sources (U.S. Bureau of Reclamation, 1983b). The remaining one-half of the concentration is caused by irrigation, reservoir evaporation, river-basin exports (mostly of headwater flows), and municipal and industrial use (fig. 43). Increases in dissolved-solids concentrations are the result of two main processes addition of dissolved solids to water from surface-water and ground-water tributary inflows and the concentration of dissolved solids through water losses by evaporation. The addition of dis- solved solids to a given amount of water results primarily from surface water percolating into the ground and dissolving mineral substances, including fertilizers, from the soil and subsoil. When the water returns to the river system, the dissolved-solids load is increased. The concen- tration of dissolved solids in water involves the loss of water by reservoir evaporation, by ex- portation of fresher water from the basin, and by evapotranspiration from irrigated crops. As water is evaporated and transpired by plants, the residual dissolved solids concentrate in the soil and remaining water. DISSOLVED-SOLIDS ANALYSIS Water development has led to changes in the quantity and quality of water flowing in the Colorado River basin. Most water-develop- ment projects in the basin were complete by 1965. For this reason, the period from 1965 to 1983 was chosen for analysis of the variations in dissolved-solids loads and concentrations within the Colorado River basin. These ana- lyses were made at 26 sites which had concur- rent records of water discharge and dissolved- solids concentrations (table 4). National Water Summary 1984 Water-Quality Issues 75 The maximum, mean, and minimum annu- al dissolved-solids load for the 26 sites in the Colorado River basin are summarized graph- ically in figure 44. In the upper Colorado River basin, the mean annual dissolved-solids loads increase in a downstream direction. The dis- solved-solids loads also increase in a down- stream direction in the lower Colorado River basin, except at site 24 below Hoover Dam. Downstream from Hoover Dam, the dis- solved-solids load actually decreases, due large- ly to decreases of water discharge in the lower Colorado River basin as a result of increased diversions behind Parker (site 25) and Imperial (site 26) Dams. Although the dissolved-solids load and water discharge decrease progressively downstream in the lower Colorado River basin, the dissolved-solids concentrations increase (fig. 45; table 4). The concentration of dissolved solids often is a better index for locating sources and re- gions of poor water quality than is the dis- solved-solids load. Maximum, mean, and mini- mum annual dissolved-solids concentrations for the 26 stations are shown in figure 45. Mean dissolved-solids concentrations are great- er than 2,500 mg/L at only 2 of the 26 stations in the Colorado River basin site 16, the Price River at Woodside, Utah (2,720 mg/L), and site 18, the San Rafael River near the Green River, Utah (2,560 mg/L). These large concen- trations are attributable primarily to dissolved solids gained as water flows through the irrigat- ed areas of these drainage basins. A smaller contribution is due to overland flow from desert-rangeland areas in these basins. TRENDS IN DISSOLVED-SOLIDS CONCENTRATIONS Trends in dissolved-solids concentrations have been investigated at 26 stations in the Colorado River basin to determine if changes have occurred between 1965 and 1983 (fig. 46). Concentrations were adjusted for flow to mini- mize the impacts of changes in flow on concen- trations and to give a more reliable indication of the actual changes in the processes that deliver dissolved solids to the streams (Craw- ford and others, 1983). The trends were statis- tically tested at the 90-percent confidence level. Data from 23 stations show a significant trend in the concentration of dissolved solids (fig. 46). Decreasing trends were detected at 20 stations on the main stem of the Colorado or on major tributaries. Increasing trends were detected for only three sites on tributary streams: site 5, on the Dolores River near Cisco, Utah; site 13, on the Little Snake River near Lily, Colo.; and site 23, on the Virgin River at Littlefield, Ariz. Only 3 of the 26 stations show no trends. Table 4. Mean annual water discharge, dissolved-solids load, and dissolved-solids concentration for 26 stations in the Colorado River basin, water years 1965 to 1983 (October 1964-September 1983) [ft /s = cubic feet per second; mg/L = milligrams per liter; ton/yr = tons per year] Site number on fig. 44 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Dissolved solids Station name Colorado River at Hot Sulphur Springs, Colo. ------- Colorado River near Glenwood Springs, Colo.- ------ Colorado River above Imperial Dam, Ariz. -Calif . ----- Water discharge (ft3/s) 230 2,200 3,700 2,400 900 6,700 520 1,700 1,900 370 2,200 1,600 640 570 660 140 6,000 130 1,200 2,200 12,800 13,300 270 12,000 10,000 8,800 Load (million ton/yr) 0.02 .56 1.45 1.31 .51 3.75 .07 .38 .57 .21 1.08 .26 .13 .37 .27 .24 2.75 .19 .19 1.00 7.06 8.00 .37 8.11 7.21 7.18 Concentration (mg/L) 90 330 540 730 1,660 770 250 240 390 970 500 280 360 1,010 490 2,720 550 2,560 170 550 560 620 1,890 700 720 850 76 National Water Summary 1984 Hydrologic Perspectives EXPLANATION 7 V Site number Dissolved-solids load Million tons per year 0.10 Maximum 0.07 Mean 0.05 Minimum 3/T77 v 145 Vi.7o COLORADO Figure 44. Maximum, mean, and minimum dissolved- solids loads for 26 stations in the Colorado River basin, 1965 to 1983. (Source: Com- piled by J. E. Kircher from U.S. Geological Survey and U.S. Bureau of Reclamation data.) Several factors may be influencing the gen- erally decreasing trends in dissolved-solids con- centration shown in figure 46. These factors include reservoir storage and operation, dissolved-solids control measures in the basin, and variations in natural runoff. The dis- solved-solids concentration in rivers generally decreases with increased streamflow on an an- nual basis. The period from 1963 to 1980 represents the most significant period of reservoir filling in the history of water development in the Colora- do River basin. The amount of water stored in Flaming Gorge Reservoir, Lake Powell, and Lake Mead collectively increased from less than 20 million acre-feet (acre-ft) in 1963 to more than 50 million acre-ft in 1980. During the period of filling, it is possible that the more dense water (high dissolved-solids concen- tration) moved to the bottom of the reservoir and the less dense water (low dissolved-solids concentration) flowed out of the reservoir. Such a situation would cause a decrease in dissolved-solids concentrations downstream of the reservoir. Another possible reason for the trends is changes in irrigation practices. Much of the farmland that had poor drainage and had excessive dissolved solids in the soil has been taken out of production. In addition, irrigation practices have changed significantly during the past 20 years, which should decrease return flows and decrease the dissolved solids input to streams. Many aquifers in the region contain large concentrations of dissolved solids but are con- fined by hundreds of feet of impermeable shales and, therefore, yield relatively little sa- line ground water through springs to the streams under natural conditions. However, when the confining layers for the saline aquifers are disrupted by mining or drilling, the saline ground water can more readily flow to the surface or reach the streams. Many saline springs and flowing wells have been identified in the basin. Some of these flowing wells have been plugged as part of dissolved-solids-control projects, such as at Meeker Dome, near Meek- er, Colo., and, therefore, could be causing a decreasing trend in some areas. The initiation of other dissolved-solids-control projects dur- ing this period also may contribute to the decline in dissolved-solids concentrations in parts of the basin. Each of these factors possi- bly contributes to the predominantly decreasing trends in dissolved-solids concentrations, but determining the relative importance of these major causes will require further study. DISSOLVED-SOLIDS CONTROL MEASURES In 1972, an amendment to the Federal Water Pollution Control Act (Public Law 92-500) set forth goals that included the resto- ration and maintenance of water quality, limi- tation of polluting effluent discharges, and eventual zero pollution discharge. Numerical criteria subsequently were established for three stations by the Colorado River Basin Salinity Control Forum, adopted by each of the seven basin States, and approved by the U.S. Envi- ronmental Protection Agency. The criteria are: National Water Summary 1984 Water-Quality Issues 77 Colorado River locations Annual flow-weighted average dissolved-solids concentration (mg/L) EXPLANATION 7V Site number Below Hoover Dam Below Parker Dam - At Imperial Dam- - 723 747 879 The overall approach to meeting the criteria is to prevent dissolved solids from entering and mixing with the river's flow. A number of agricultural, point, and diffuse sources of dis- solved solids have been identified throughout the basin for possible interception. Another source of great interest in the dissolved-solids concentration of the Colorado River is the international treaty with Mexico concerning the river's water quality as it crosses the international border. In June 1974, Congress enacted the Colora- do River Basin Salinity Control Act (Public Law 93-320) which directed the Secretary of the Interior to expedite planning studies on 12 salinity-control projects of a basinwide pro- gram to control the dissolved solids of Colora- do River water and to construct four select salinity-control projects. Title I of the Act authorized the construction of facilities and onfarm measures to enable the United States to comply with its obligations under Minute No. 242 of the International Boundary and Water Commission, United States, and Mexico. In brief, Minute 242 requires that water delivered to Mexico have an average annual dissolved- solids concentration that is no more than 115 mg/L (± 30 mg/L) greater than the concentra- tion in Colorado River water arriving at Imperi- al Dam upstream of the United States-Mexican border. At the State level, all seven Colorado River basin States have appointed representatives to the Colorado River Basin Salinity Control Forum and to the Colorado River Basin Salini- ty Control Advisory Council to coordinate State actions and to advise the Federal Govern- ment on the State views on issues affecting water-quality standards and ways to meet those standards. At the Federal level, dissolved- solids-control efforts of the U.S. Department of the Interior, the U.S. Environmental Protec- tion Agency, and the U.S. Department of Agriculture are coordinated through an Intera- gency Salinity Control Committee to improve management of irrigated agriculture through research and onfarm improvements and to implement selected structural and nonstructural control measures (U.S. Bureau of Reclamation, 1983c). Specific solutions to the dissolved-solids problem depend, in part, on the mechanisms by Dissolved-solids concentration Milligrams per liter 440 Maximum 250 Mean 170 Minimum Range of mean annual concentration | T 0-500 V 501-1000 V 1001-2500 Greater than 2500 LOWER COLORADO RIVER BASIN I which the dissolved solids enter the river. Sev- eral dissolved-solids-control measures for the Colorado River basin currently are under evaluation: 1. Point-source controls are proposed to remove salt from such local areas as miner- al springs, abandoned oil wells, and gey- sers. To date (1984), several abandoned oil wells have been plugged in the Meeker area, decreasing dissolved-solids loads lo- cally by as much as 57,000 ton/yr. Propos- als are being formulated for the control of Figure 45. Maximum, mean, and minimum dissolved- solids concentrations for 26 stations in the Colorado River basin, 1965 to 1983. (Source: Compiled by J. E. Kircher from U.S. Geologi- cal Survey and U.S. Bureau of Reclamation data.) 78 National Water Summary 1984 Hydrologic Perspectives EXPLANATION 7 V Site number Trend in dissolved-solids concentration at the 90-percent confidence level Figure 46. Trends in dissolved-solids concentrations at 26 stations in the Colorado River basin, 1965 to 1983. (Source: Compiled by J. E. Kircherfrom U.S. Geoiogical Survey and U.S. Bureau of Reclamation data.) other point sources within the basin, such as the Glenwood-Dotsero mineral springs. 2. Diffuse-source controls of dissolved solids being considered include watershed man- agement, land treatment, and the collection and disposal of irrigation-return flows. 3. Irrigation controls are proposed to decrease salt loadings by improving onfarm irriga- tion systems and irrigation management practices that result in the leaching of salts from marine shales and other saline de- posits. Controlling the dissolved solids in the Colorado River basin has challenged and will continue to challenge state-of-the-art technolo- gy and water-management skills. SELECTED REFERENCES Colorado River Basin Salinity Control Forum, 1984, Water quality standards for salinity, Colorado River System, 1984 Review: Bountiful, Utah, Colorado River Basin Salinity Control Forum, 129 p. Crawford, C. G., Slack, J. R., and Hirsch, R. M., 1983, Nonparametric tests for trends in water- quality data using the Statistical Analysis Sys- tem: U.S. Geological Survey Open-File Report 83-550, 102 p. French, R. H., ed., 1984, Salinity in watercourses and reservoirs: Boston, Butterworth, 622 p. lorns, W. V., Hembree, C. H., and Oakland, G. L., 1965, Water resources of the upper Colorado River basin Technical report: U.S. Geological Survey Professional Paper 441, 370 p. Jonez, A. R. 1984, Controlling salinity in the Colorado River Basin, the arid West, in French, R. H., ed., Salinity in watercourses and reser- voirs: Boston, Butterworth, p. 337-347. U.S. Bureau of Reclamation, 1983a, Quality of water Colorado River basin, Progress Report No. 11, January 1983: Denver, U.S. Bureau of Reclamation, Colorado River Water Quality Office, 149 p. __1983b, Colorado River improvement program, Status Report, January 1983: Denver, U.S. Bureau of Reclamation, Colorado River Water Quality Office, 126 p. __1983c, Salinity Update, Special Edition, Janu- ary 1983: Denver, U.S. Bureau of Reclamation, Colorado River Water Quality Office. U.S. Department of Agriculture, 1983, 1983 Annual report, Colorado River Basin Salinity Control Program: 24 p. U.S. Geological Survey, 1984, National water sum- mary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. National Water Summary 1984 Water-Quality Issues 79 DISSOLVED SOLIDS IN THE ARKANSAS RIVER BASIN By Jerry D.Stoner INTRODUCTION The Arkansas River originates in the heart of the Rocky Mountains and flows 1,459 miles (mi) to its confluence with the Mississippi River (fig. 47). It drains parts of seven States Arkansas, Colorado, Kansas, Missouri, New Mexico, Oklahoma, and Texas. The drainage area of the Arkansas River basin is 160,576 square miles (mi2), an area larger than the State of California. From the eastern slopes of the Rocky Mountains, the river flows across the Great Plains of Colorado and Kansas and into Oklahoma, where it flows through a transition zone from the Great Plains to the Ozark and Ouachita Mountains and then flows across the Mississippi River flood plain to its confluence with the Mississippi River. Precipitation in the Arkansas River basin ranges from an annual average of 15 inches (in.) in eastern Colorado to an annual average of 49 in. in Arkansas. Because of the increase in precipitation from west to east, 80 percent of the total basin mean annual water discharge at the mouth of the river originates downstream from Tulsa, Okla., the lower one-third of the river's total length. Tributaries that contribute the most water enter the Arkansas River in Oklahoma and south-central Kansas. These tributaries are the Salt Fork Arkansas, Cimar- ron, Verdigris, Neosho, Illinois, Canadian, Walnut, and Ninnescah Rivers. Throughout its length, the Arkansas River and most of the major tributaries are affected directly by human activities. Reservoirs, which have been constructed on the mainstem, as well as on many of the tributaries, are mostly in Oklahoma. The operation of these reservoirs affects the flow regime by decreasing the max- imum flows somewhat and increasing the mini- mum flows. In Colorado, upstream and downstream of the John Martin Reservoir, water is diverted often from the Arkansas River for irrigation, and the streamflow decreases through this area of diversions. The average annual water dis- charge near Coolidge, Kans., (table 5, site 3) is about 20 percent of the mean annual water discharge 217 mi upstream at Portland, Colo. (site 1), and about 50 percent of the mean annual water discharge 58 mi upstream just below John Martin Reservoir, Colo. (site 2). Diversion activities in the upper one-third of the length of the Arkansas River have altered drastically the water discharge. Downstream from Tulsa, Okla. (site 11), the Arkansas River becomes the McClellan- Figure 47. Maximum, mean, and minimum dissolved- solids loads for 18 stations in the Arkansas River basin, 1968 to 1982. (Source: Compiled by J. D. Stoner from U.S. Geologi- cal Survey data.) EXPLANATION 4 V Site number Dissolved-solids load Million tons per year 1,03 Maximum Mean Minimum Range of mean annual load V 0.00-1.00 T 2.51-10.00 NEW MEXICO 80 National Water Summary 1984 Hydrologic Perspectives Table 5. Mean annual water discharge, dissolved-solids load, and dissolved-solids concentrations for 18 stations in the Arkansas River basin, water years 1968 to 1982 (October 1967-September 1982) [ft /s = cubic feet per second; mg/L = milligrams per liter; ton/yr = tons per year] Site number Station name on fig. 47 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Arkansas River below John Martin Reservoir, Colo. - - - - Arkansas River at Arkansas City, Kans. --------- Walnut River at Winfield, Kans.- ------------ Arkansas River near Van Buren, Ark. ---------- Arkansas River below Little Rock, Ark. --------- Dissolved solids Water discharge (ft3/s) '657 222 89 576 488 1,995 887 754 4,870 1,197 7,449 4,700 9,311 1,596 5,413 33,700 36,310 44,340 Load (million Concentration ton/yr) (mg/L) 0.14 .33 .29 .55 .20 1.21 .29 1.22 3.02 2.74 7.32 .96 1.45 .16 1.20 10.70 11.50 11.51 273 2,632 3,673 1,575 627 954 579 3,127 882 5,077 1,101 252 165 112 259 373 397 301 Period of record: 1975 to 1982. Kerr Waterway and provides an inland water- way for barge traffic from Tulsa to the Missis- sippi River. This is the primary use of the lower one-third of the Arkansas River. The waterway begins as a navigation improvement on the Verdigris River at Catoosa, Okla., on the east- ern edge of the Tulsa metropolitan area and continues to a point downstream from Inola, Okla. (site 12), where it joins the Arkansas River and follows it from there to the Mississip- pi River. The primary use of Arkansas River water in the middle one-third of the river basin is for irrigation. The high dissolved-solids concentra- tions in this reach of the river limits its use for other purposes. SOURCES OF DISSOLVED SOLIDS Dissolved solids in the Arkansas River basin are from two major sources. In the upper reach of the river (eastern Colorado and west- ern Kansas), the source is irrigation flow. Where water is diverted from the river for irrigation, some of the water applied to the cropland returns to the river. This return flow carries dissolved material from soil and rock. In the lower reach of the river (south-central Kansas and northwestern Oklahoma), the source is ground water discharging to the surface-water system from rocks of Permian age, which contain sodium chloride and other naturally occurring salts (Gogel, 1981; Leonard and Kleinschmidt, 1976; Reed, 1982). This water is quite saline, and, in many areas, the dissolved-solids concentrations exceed 35,900 milligrams per liter (mg/L) (Gogel, 1981). In Kansas, the saline-water discharge is to the Little Arkansas River and, through several minor tributaries, directly to the Arkansas Riv- er. In Oklahoma, the saline-water discharge is to the Salt Fork Arkansas and the Cimarron Rivers. These dissolved-solids loadings, particular- ly chloride, make the water in the Arkansas River upstream of Tulsa, Okla., (site 11), unsuitable for many uses without pretreatment. The national drinking-water criterion for chlo- ride is 250 mg/L (U.S. Environmental Protec- tion Agency, 1982b), and this criterion general- ly is exceeded more than 50 percent of the time in the Oklahoma reach of the Arkansas River (Stoner, 198la). For most of the upper two- thirds of its length, the Arkansas River is un- suitable for public water supply and for most commercial and industrial uses without treat- ment to reduce the chloride concentration. Within Oklahoma, the high dissolved-solids concentration in the Arkansas, Salt Fork Arkansas, and Cimarron Rivers decreases the use of these rivers as sources of water for irrigation (Stoner 198la, b). Most of the time, the irrigation salinity hazard (Wilcox, 1955) of these streams ranges from high to very high. National Water Summary 1984 Water-Quality Issues 81 DISSOLVED-SOLIDS ANALYSIS In the Arkansas River basin, human activi- ties such as construction and operation of di- version structures, dams, reservoirs, and water- ways have continually changed the flow pat- terns in the basin. The rate of construction had slowed by 1968, and the flow patterns within the basin are now mostly the result of opera- tional rather than construction activities. Therefore, the period from 1968 to 1982 was selected for an analysis of dissolved solids in the basin to minimize the effect of project con- struction. Eighteen sites within the Arkansas River basin had discharge and dissolved-solids data available for most of this period (see table 5). DlSSOLVED-SOLIDS LOADS Within the Arkansas River basin the amount of dissolved solids transported in- creases in the downstream direction (fig. 47). This downstream increase in load is the cumula- tive result of the contributions of dissolved solids from tributaries and ground-water inflow. Of these inflow sources, the major increases in the load of the mainstem are due to irrigation return flow and natural brine inflow. Thus, although the mean annual water dis- charge in the Arkansas River near Coolidge, Kans. (site 3), is only about 20 percent of the mean annual water discharge upstream at Port- land, Colo. (site 1), the mean annual dissolved- solids load near Coolidge is twice as great as the dissolved-solids load at Portland. Downstream from the irrigation diversion areas in Kansas, the water discharge in the Arkansas River again increases through tributary and ground-water inflow. The mean annual water discharge of the Arkansas River is about 19 times greater at Arkansas City, Kans. [(site 6; 1.45 million acre-feet per year (acre-ft/yr)], than it is at the site near Coolidge (76,000 acre-ft/yr). In this same reach of the river the mean annual dissolved-solids load increases about four times, from 290,000 tons per year (ton/yr) near Coolidge, Kans., to 1.21 million ton/yr at Arkansas City. The Cimarron and the Salt Fork Arkansas Rivers enter the Arkansas River between Arkansas City, Kans., and Tulsa, Okla. The dissolved-solids input from these two rivers causes a dramatic increase in the load in the mainstem. The rivers contribute 34 percent of the mean annual dissolved-solids load for the entire basin while contributing only 4 percent of the basin's mean annual water discharge. Of these two streams, the Cimarron River is the major contributor. This stream contributes 24 percent of the basin's mean annual load while contributing only 3 percent of the basin's mean annual water discharge. Four major tributaries enter the Arkansas River between Tulsa, Okla., and Van Buren, Ark. These tributaries (sites 12-15) contribute another 33 percent of the basin's mean annual dissolved-solids load, which is about the same as the combined contribution from the Cimar- ron and Salt Fork Arkansas Rivers. However, their combined mean annual water discharge, which is 15 million acre-ft, or 47 percent of the basin's mean annual water discharge, is more than 10 times the combined mean annual water discharge of the Salt Fork Arkansas and Cimar- ron Rivers (1.42 million acre-ft). As the Arkansas River flows through the State of Arkansas, its mean annual water discharge increases by about 30 percent, from 24.4 mil- lion acre-ft near Van Buren (site 16) to 32.1 million acre-ft below Little Rock (site 18). The mean annual dissolved-solids load, however, increases in this reach by only 6 percent, from 10.7 million to 11.5 million tons. Altogether, the major tributaries of the Arkansas River contributed 71 percent of the basin's mean annual dissolved-solids load. The remaining 29 percent is contributed by minor tributaries and undefined ground-water inflow. DlSSOLVED-SOLIDS CONCENTRATIONS Information on dissolved-solids concentra- tions, which directly determine the suitability of the river water for various uses, often is over- shadowed by information on dissolved-solids loads. It is important to know the volume of water being discharged. At sites 6, 8, and 15, for example, the mean loads are almost the same, but the mean concentrations vary consid- erably, which reflect the differences in the water discharges. Although the mean loads for two of these sites, Salt Fork Arkansas and Canadian Rivers, are nearly the same, the mean concentration for the Salt Fork Arkansas River (site 8) is 12 times greater than that of the Canadian River (site 15), which makes the Salt Fork Arkansas useless for most purposes. At four sites in the basin (fig. 48), mean dissolved-solids concentrations were greater than 2,000 mg/L, the maximum limit for most irrigation (site 2, 2,632 mg/L; site 3, 3,673 mg/L; site 8, 3,127 mg/L; and site 10, 5,077 mg/L). These four sites correspond to the areas of irrigation return flow and natural brine inflow that were discussed above. Moving downstream from Tulsa (site 11), the dissolved-solids concentrations in the Arkansas River decrease in the downstream direction due to less-saline tributary inflow. This downstream decrease is shown in figure 48 by site 11, where 82 National Water Summary 1984 Hydrologic Perspectives Site number Dissolved-solids concentration Milligrams per liter 3050 Maximum Range of mean annual concentration V 0-500 V 1001-2500 NEW MEXICO Figure 48. Maximum, mean, and minimum dissolved solids concentrations for 18 stations in the Arkansas River basin, 1968 to 1982. (Source: Compiled by J. D. Stoner from U.S. Geologi- cal Survey data.) the mean concentration was 1,101 mg/L, and by site 18, where it was 301 mg/L. The influence of irrigation activities in the upper part of the Arkansas River basin is reflected in the increase in dissolved-solids con- centration (from 2,632 to 3,673 mg/L) between sites 2 and 3 (fig. 48). This increase in dis- solved-solids concentration is accompanied by a slight decrease, 12 percent, in the mean annu- al water discharge. Downstream from Coo- lidge, Kans., for about 140 mi, water discharge in the Arkansas River continues to decrease due to human activities, predominantly irrigation diversion. However, adequate dissolved-solids concentration data from 1968 to 1982 are not available to determine the effects on concentra- tion in this reach. Downstream from the major area of diversions, water discharge in the Arkansas River increases, and dissolved-solids concentration decreases. At site 4, mean annu- al water discharge is more than five times greater, than at site 3, and the mean dissolved- solids concentration is less than one-half of that at site 3. The influence of the natural brine inflows into the Salt Fork Arkansas and Cimarron River basins is reflected in figure 48, where the mean dissolved-solids concentrations were 3,127 mg/L in the Salt Fork Arkansas River (site 8) and 5,077 mg/L in the Cimarron River (site 10); maximum concentrations at these sites were 7,800 and 15,700 mg/L, respectively. These high concentrations severely limit the suitability of these stream waters for most common uses. In these two basins within Ok- lahoma, more than 95 percent of the total water withdrawals is ground water. The surface water used is from impoundments on streams in the areas that have better water quality. The impact of these two streams on dissolved-solids concentration in the Arkansas river is not severe, however. The mean dissolved-solids concentration in the Arkansas River at site 6, which is above the confluences of the two streams with the Arkansas River, is 954 mg/L, whereas the mean concentration at site 11, below the confluences, is 1,101 mg/L. This change amounts to an increase of only 13 percent of the mean concentration. This small increase is due mostly to the dilution of the saline inflow by increased water discharge in the reach. Between sites 6 and 11, mean annual water discharge in the Arkansas River increases by 3.93 million acre-ft, of which only 1.40 million acre-ft can be attributed to the Salt Fork Arkansas and Cimarron Rivers. Downstream from site 11, the Verdigris, the Neosho, the Illinois, and the Canadian Rivers flow into the Arkansas River. The dissolved-solids concentration of these tribu- taries is significantly less (fig. 48), and the mean dissolved-solids concentration in the Arkansas River at site 16, downstream from these tribu- taries, is 373 mg/L, or about one-third of that at site 11. In Arkansas, the dissolved-solids concentrations of the inflowing waters to the Arkansas River, generally are less than 100 mg/L and average about 70 mg/L. National Water Summary 1984 Water-Quality Issues 83 TRENDS IN DISSOLVED-SOLIDS CONCENTRATIONS Trend analyses for the dissolved-solids con- centrations were performed for the 18 sites selected for this study to identify changes that might have occurred during the 1968 to 1982 period. Because dissolved-solids concentra- tions normally decrease as water discharge in- creases, the dissolved-solids concentrations were flow adjusted (Crawford and others, 1983) to minimize the effects of trends in water discharges during the period of record. Of the 18 sites, 3 had increasing trends in concentration, 4 had decreasing trends, and 11 had no change (fig. 49). The decreases in concentration on the Arkansas River at sites 3 and 6 may be due to improved irrigation prac- tices during the period. However, no mech- anism was readily apparent to explain the in- dicated decreasing trends in concentration at these sites or at site 8 on Salt Fork Arkansas River. The decreasing trend indicated for the Arkansas River at site 9 probably is the down- stream propogation of the trends at sites 6 and 8, whatever their causes. The increasing trends in dissolved-solids concentration on the Canadian River (site 15) may be due to evapo- ration or operational practices at Eufaula Reservoir just upstream of that site. The in- creases in concentration in the Arkansas River at sites 16 and 18 also may be due to reservoir effects; however, no change was indicated at site 17, which also is just downstream from a reservoir. Other mechanisms affect the concentra- tions of dissolved solids, but their relative im- portance to the dissolved-solids loads of the Arkansas River is unknown. Increased ground-water pumping can decrease the ground-water gradients toward the streams and thereby diminish the natural brine inflows. Improved treatment practices can decrease point-source loading, whereas, increased popu- lation can increase point-source loadings. None of the mechanisms offered has been investigated or confirmed, and the trends in- dicated may be due to entirely different, un- identified causes. SUMMARY The large dissolved-solids load in the Arkansas River is due primarily to irrigation return flows and natural brine inflows. The mean dissolved-solids load transported out of the basin from 1968 to 1982 was 11.5 million ton/yr, of which 3.96 million tons, or 34 per- cent, was contributed by the Salt Fork Arkansas and Cimarron Rivers, although these two streams contributed only 4 percent of the mean annual water discharge from the basin. The major tributaries entering the Arkansas River between Tulsa, Okla., and Van Buren, Ark., contributed another 33 percent of the mean annual dissolved-solids load out of the basin; however, these tributaries also contribut- ed 47 percent of the basin's mean annual water discharge. The natural brine inflow to the Arkansas River above the confluences of the Figure 49. Trends in dissolv- ed-solids concentrations at 18 stations in the Arkansas River basin, 1968 to 1982. (Source: Compiled by J. D. Stoner from U.S. Geologi- cal Survey data.) 84 National Water Summary 1984 Hydrologic Perspectives Salt Fork Arkansas and Cimarron Rivers con- tributed about 5 percent of the basin's dis- solved-solids load. In Colorado and Kansas, irrigation return flow contributed about 5 per- cent of the basin's dissolved-solids load. The high dissolved-solids concentrations in the basin also are due to the two major sources of dissolved solids. Mean concentrations great- er than 2,500 mg/L are associated with irriga- tion return flow in the upper reach of the Arkansas River and with the natural brine inflows in the Salt Fork Arkansas and Cimar- ron River basins. The high dissolved-solids concentrations are diluted by inflows of better water quality from the major tributaries, the Verdigris, the Neosho, the Illinois, and the Canadian Rivers, which enter the Arkansas River downstream from Tulsa, Okla. Trend analyses show that dissolved-solids concentrations in the basin have remained for the most part unchanged although four stations had decreases in concentrations and three sta- tions had increases in concentration from 1968 to 1982. The two major sources of dissolved solids in the Arkansas River basin contributed almost one-half (49 percent) of the mean annual dis- solved-solids load in the basin during the 1968 to 1982 period. The mean annual water dis- charges associated with these major sources was about 8 percent of the total basin mean annual discharge. Although irrigation return flow con- tributes to the total basin dissolved-solids load (5 percent), the natural brine inflow is the primary source (44 percent) of the total basin dissolved solids load. Therefore, the major dissolved-solids load problem in the Arkansas River basin is due much more to the natural brine inflow than to human activities. Studies of methods to control these brine inflows have been conducted by the U.S. Army Corps of Engineers (DeGeer, 1971;Rought, 1984). Con- struction of diversion dikes, evaporation ponds, and other control structures, however, has not been authorized. SELECTED REFERENCES Crawford, C. G., Slack, J. R., and Hirsch, J. M., 1983, Nonparametric tests for trends in water- quality data using the Statistical Analysis Sys- tem: U.S. Geological Survey Open-File Report 83-550, 102 p. DeGeer, M. W., 1971, Natural chloride pollution Arkansas and Red River basins: University of Oklahoma, Norman, Okla., Annals of the Ok- lahoma Academy of Science Publication No. 2, p.42-46. Gogel, T., 1981, Discharge of salt water from Permian rocks to major stream-aquifer systems in central Kansas: Kansas Geological Survey, Chemical Quality Series 9, 60 p. Leonard, R. B., and Kleinschmidt, M. K., 1976, Saline water in the Little Arkansas River basin area, north-central Kansas: Kansas Geological Survey, Chemical Quality Series 3, 24 p. Oklahoma Water Resources Board, 1975, Oklahoma comprehensive water plan: Oklahoma Water Resources Board Publication No. 60, 108 p. Reed, J. E., 1982, Preliminary projections of the effects of chloride-control structures on the Quaternary aquifer at Great Salt Plains, Ok- lahoma: U.S. Geological Survey Water- Resources Investigations Report 80-120, 45 p. Rought, B. G., 1984, The Southwestern salinity situation The Rockies to the Mississippi River, in French, R. H., Salinity in water courses and reservoirs: Boston, Butterworth, p. 115-124. Stoner, J. D., 198la, Water type and suitability of Oklahoma surface waters for public supply and irrigation; Part 1, Arkansas River mainstem and Verdigris, Neosho, and Illinois River basins through 1978: U.S. Geological Survey Water- Resources Investigations Report 81-33, 197 p. __1981b, Water type and suitability of Oklahoma surface waters for public supply and irrigation; Part 2, Salt Fork Arkansas and Cimarron River basin through 1978: U.S. Geological Survey Water-Resources Investigations Report 81-39, 150 p. __1981c, Water type and suitability of Oklahoma surface waters for public supply and irrigation; Part 3, Canadian, North Canadian, and Deep Fork River basins through 1979: U.S. Geologi- cal Survey Water-Resources Investigations Report 81-80,210 p. U.S. Environmental Protection Agency, 1982a, Maximum contaminant levels (subpart B of part 141, National interim primary drinking-water regulations): U.S. Code of Federal Regula- tions, Title 40, parts 100-149, revised as of July 1,1982, p. 315-318. __1982b, Secondary maximum contaminant levels (section 143.3 of part 143, National secondary drinking-water regulations): U.S. Code of Fed- eral Regulations, Title 40, parts 100-149, re- vised as of July 1, 1982, p.374. Wilcox, L. V., 1955, Classification and use of irriga- tion waters: U.S. Department of Agriculture Circular No. 969, 19 p. National Water Summary 1984 Water-Quality Issues 85 PESTICIDES IN RIVERS OF THE UNITED STATES By Robert J. Gil Horn INTRODUCTION Large-scale use of chemicals for pest con- trol began as early as 1840, when sulfur dust was found to be effective for controlling pow- dery mildew on grapes. By 1890, at least 40 insecticides were patented, most containing arsenic or sulfur as the active ingredient (Dahm, 1970). Then, during the 1940's, the insecticidal properties of DOT and lindane were discovered, and, in the following years, numer- ous other synthetic organic pesticides were developed. Most pesticides are either insecti- cides for controlling insects or herbicides for controlling weeds. By 1964, the chemical in- dustry had developed more than 10,000 com- mercial pesticide products that contained vari- ous combinations and formulations of over 250 basic active ingredients, mostly synthetic organ- ic compounds (Eichers and others, 1968). The synthetic organic pesticides that have come into use since World War II have been proven to be cost-effective against many pests. They have helped increase agricultural produc- tivity by improving yields and reducing labor requirements. Pesticides also have been used widely for other purposes such as the control of roadside and right-of-way weeds and house and garden pests. Along with the benefits of pesticides, however, come environmental costs such as damage to fish and wildlife and the potential health effects of human consumption of pesti- cides in food and water. Pesticides, for exam- ple, caused more than 1,000 fishkills in United States waters from 1961 to 1975 and accounted for about 18 percent of all reported fishkills (U.S. Environmental Protection Agency, 1979). Most of the pesticides discussed in this article have been shown to be potentially haz- ardous to human health if present in drinking water, and water-quality criteria on acceptable concentrations for both drinking water and aquatic biota have been established (U.S. Envi- ronmental Protection Agency, 1980). No simi- lar criteria have been established for pesticides in the bed material (bottom sediment) of rivers or lakes because of a lack of sufficient knowl- edge about the interactions of contaminants in bed materials with water and aquatic organ- isms. Although plants and soil are the recipients of most pesticides applied, water is the princi- pal vehicle for movement after application. Water transports pesticides by eroding pesti- cide-laden soil or powders applied with the pesticide and by dissolving pesticides. The water and pesticides may seep through the soil to recharge ground water or may run off into urban or agricultural drains, ditches, and small streams to rivers and lakes. One of the national water-quality issues identified in the 1983 Na- tional Water Summary (U.S. Geological Sur- vey, 1984, p. 75) was nonpoint-source pollution by pesticide residues in agricultural runoff. To examine the extent and trends of pesti- cide contamination of major rivers of the Unit- ed States, the U.S. Geological Survey and the U.S. Environmental Protection Agency cooper- atively monitored levels of selected pesticides in the water and bed material at more than 150 river sites (fig. 50) during water years 1975 to 1980 (Feltz and others, 1971). The findings discussed below are based on a detailed analysis of data from the Pesticide Monitoring Network for the conterminous United States (Gilliom and others, 1985). GENERAL CHARACTERISTICS OF PESTICIDES The Pesticide Monitoring Network focused on 22 pesticides of particular environmental concern during the 1970's. These pesticides, which represent a wide range of chemical characteristics, toxicity, and uses, included or- ganochlorine and organophosphate insecticides and chlorophenoxy and triazine herbicides (table 6). Figure 50. Location of stream- sampling stations of the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Monitor- ing Network in the conter- minous United States, 1975 to 1980. 86 National Water Summary 1984 Hydrologic Perspectives Figure 51. Trends in national use of herbicides and in- secticides on major crops, 1964 to 1982. (Source: Com- piled by R. J. Gilliom from data in Eichers and others, 1970; Andrilenas, 1974; Eichers and others, 1978; and U.S. Department of Agriculture, 1983. Reported use in 1982 was adjusted according to past use pat- terns to account for use in States for which there were no data.) An important aspect of some pesticides and other synthetic organic chemicals is that many are thought to be hazardous to aquatic life and human health at concentrations that are lower than the concentrations that can be reliably detected and measured by commonly applied analytical methods; for example, the aquatic- life criterion for DOT is 0.001 microgram per liter 0-ig/L), and the human-health criterion is 0.0002 ^g/L, yet the limit of detection for analyses of DOT in Pesticide Monitoring Net- work samples was 0.05 ^g/L (table 6). In other words, even though an analysis does not detect the presence of a pesticide, the pesticide still may be present in the sample at a concentration believed to be hazardous. Because pesticide concentrations are often diluted by river water to levels below detection limits, monitoring pesticide levels and interpreting pesticide data are difficult. Two characteristics that account for varia- tions in environmental behavior of different pesticides are solubility in water and persistence in the environment (table 6). Chemicals with low solubility and high persistence, such as many of the organochlorine insecticides, gener- ally are found in association with particulate bed materials or suspended sediment and may not degrade for several years. These chemicals also tend to accumulate in aquatic organisms and their predators, and, over time, they can reach harmful concentrations in organisms 1964 1966 1971 1976 1982 even if concentrations in water and bed materi- al are low. Conversely, other types of chemi- cals, such as the organophosphate insecticides, are highly soluble in water and usually last only days or weeks before degrading. Even though such chemicals usually degrade to a benign form and do not accumulate in organisms, most are more acutely toxic than the organo- chlorine insecticides. The herbicides monitored also are readily soluble in water, but they generally persist for weeks to months. In gener- al terms, therefore, the organochlorine insecti- cides are the least soluble and most persistent, the organophosphate insecticides are highly soluble and the least persistent, and the herbi- cides are highly soluble and moderately persist- ent. USE OF PESTICIDES All the pesticides analyzed in the Pesticide Monitoring Network are synthetic organic chemicals and, thus, only appear in the envi- ronment as a result of their use, disposal, or manufacture. The greatest release of pesticides was on farms (Eichers and others, 1978), of which about 98 percent was applied to crops and 2 percent to livestock. Corn, cotton, wheat, sorghum, rice, other grains, soybeans, tobacco, peanuts, alfalfa, other hay and for- age, and pasture and range land accounted for 85 percent of the pesticides used on crops. Nationally, insecticide use on crops is de- clining gradually, whereas herbicide use is increasing (fig. 51). Much of the decline in amount of insecticide applied is due to the use of more potent new chemicals. Since 1976, for example, fenvalerate and permethrin, two new insecticides for use on cotton which require very low application rates, largely have re- placed toxaphene and methyl parathion, which were routinely applied at much higher applica- tion rates (McDowell and others, 1982). PATTERNS AND TRENDS IN PESTICIDE DETECTIONS The percentage of samples that contained detectable concentrations of pesticides and the percentage of stations at which pesticides were detected are listed in table 7 for water and bed material, respectively. Relatively few water samples contained detectable pesticide concen- trations; the most common pesticides in water were lindane, diazinon, and atrazine. In bed material, however, some organochlorine com- pounds were detected relatively frequently, al- though organophosphate insecticides and the herbicides were detected very rarely. Data from the Pesticide Monitoring Network indicate that less than 10 percent of almost 3,000 water samples and less than 20 percent of almost National Water Summary 1984 Water-Quality Issues 87 1,000 bed-material samples contained detecta- ble concentrations of any of the pesticides for which analyses were made. ORGANOCHLORINE INSECTICIDES Use and Occurrence For most of the organochlorine insecti- cides, a combination of increasing regulatory restriction and decreasing effectiveness due to insect resistances has caused a dramatic de- crease in use since the mid-1960's (table 6). Overall use of organochlorine insecticides on major crops has declined from a 63-percent share of all insecticide use in 1964 to a 40- percent share in 1971 to a 28-percent share in 1976 (Eichers and others, 1970, 1978). Data for 1982 show that this share has decreased further to less than 10 percent (U.S. Department of Agriculture, 1983). Only toxaphene retained a major share of total use through the 1970's though its use also had declined greatly by 1982. Despite these decreases in farm use, chlordane, heptachlor, methoxychlor, and tox- aphene still are used heavily for other purposes, as indicated by the disparity between total use and farm use (table 6). Chlordane and hepta- chlor, for example, are used extensively for termite control. Frequencies of detection of organochlorine insecticides (table 7) reflect the combined ef- fects of different detection limits, amounts of use, persistence and solubility, and degradation products (table 6). A striking feature of table 7 is the contrast between the very low frequency of detection of organochlorine compounds in water samples and the relatively high frequency of detection in bed material. The low number of detections in water samples compared to bed material is consistent with the low solubility of these compounds and their tendency to associ- ate with particulate matter. A key factor that potentially affects the frequency of detection of a pesticide is the amount used. On the basis of historic use, toxaphene, methoxychlor, DOT, and aldrin should occur most frequently. However, the analytical methods for toxaphene and methoxy- chlor are the least sensitive of the organochlo- rine insecticides; consequently, they were sel- dom detected. DOT degrades over time into ODD and DDE. Though DOT was detected fairly often in bed material, its degradation products, ODD (low use) and DDE (not used), were detected even more often. Aldrin, which has a low detection limit but degrades fairly rapidly to dieldrin, was seldom detected in either water or bed material. Its more persistent degradation product, dieldrin, was detected in about 29 percent of bed-material samples despite sub- stantially less direct use of dieldrin as a pesticide. In contrast to these more heavily used compounds, lindane was used relatively little and yet was the most frequently detected or- ganochlorine in water. The combination of lindane's relatively high solubility, high persist- ence, and a low detection limit probably ex- plains this. Chlordane, used only slightly more than lindane, was almost never detected in water samples but was one of the most frequent pesticides detected in bed-material samples. Chlordane is one of the most persistent of the organochlorine insecticides and is only one- third as soluble as lindane. Thus, the patterns of detection that would be expected from use data alone do not occur because of varying chemical properties and analytical capabilities. Trends Over Time Concentrations of organochlorine insecti- cides in both water and bed material appear to have decreased erratically but gradually since about 1976 or 1977. Frequencies of detection for all stations and samples are shown in figure 52. Average numbers of detections per 100 samples were computed by summing the num- ber of detections for all organochlorine com- pounds for a given year and dividing by the number of samples analyzed for organochlo- rines that year. The maximum possible number of detections per 100 samples is 1,100 because 11 organochlorine insecticides were monitored. Comparison of Pesticide Monitoring Network data for water samples to data from an earlier U.S. Geological Survey study of pesticides in western rivers (Schulze and others, 1973) indi- cate a marked reduction in concentrations since the late 1960's. For 16 stations identically or EXPLANATION Bed sediments 100 05 w 80 || ££{2 ^?_j 60 OC £ t/5 3^<c 40 ^zS s s < a: £5° > u. <0 20 n 1 '] DCU 9CUIII ICI 119 jj^^ Water - - - *-::~ f ' _ I, , ^ ::; :" ""'"" 1 1,100 detections are possible in each 100 samples !:. <-. r"i Jp No data for bed sediments in 1980 Figure 52. Frequency of detection of organochlorine insecticides in water and bed-material samples from stations in the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Moni- toring Network, 1975 to 1980. 88 National Water Summary 1984 Hydrologic Perspectives Table 6. Selected characteristics and uses of pesticides monitored by the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Monitoring Network, 1975 to 1980 [/xg/L, microgram per liter; Ib/yr = pounds per year; nd, no available data; nr, none reported] Characteristics Water-quality Chemical criteria2 Detection (wQ/U Solubility3 limit1 Human Aquatic (/xg/L) health life Relative persistence Uses Total use, Principal National use on farms5 1981 6 uses and (million Ib/yr) (million within sources pesticide group4 1966 1971 1976 1982 Ib/yr) Organochlorine insecticides Aldrin - - - 0.01 0.0007 0.002 13 Low Corn 15 7.9 0.9 nr 0.8 (Most farm uses cancelled 1974) Dieldrin - - .03 .0007 .002 22 Medium Termite control, .7 .3 nr nr 0 degradation (Most farm uses cancelled 1974) Chlordane - .15 .005 .004 56 High product of aldrin. Corn, termites, .5 1.9 nr nr 9.6 general purpose. (Most farm uses cancelled 1974) ODD - - - DDE- - - - DOT- - - - Endrin - - - Heptachlor epoxide - Lindane - - Methoxychlor Toxaphene - .05 .0002 .001 .03 .0002 .001 .05 .0002 .001 .05 *1 .002 .01 .003 .004 .01 *4 .08 .10 *100 *.03 .25 .007 .013 5 10 17 14 30 150 3 400 do do do nd Low Medium nd nd Fruits and vegetables, 2.9 .2 nr degradation (Cancelled 1972) product of DOT. Degradation product nr nr nr of DOT and ODD. Cotton, fruits, 27 . 1 nr vegetables, (Cancelled 1972) general purpose. Cotton, wheat .6 1.4 .8 Degradation product 1.5 1.2 .6 of heptachlor which is used on corn, and termite control. Livestock, seed .7 .7 .2 treatment, general purpose. Livestock, alfalfa, 2.6 3.0 3.8 general purpose. Cotton, livestock 35 37 33 nr nr nr nr nr nr .6 5.9 0 0 0 .3 2.0 .8 5.0 16 Organophosphate insecticides Diazinon - - Ethion - - - Malathion - Methyl parathion- Methyl trithion- - Parathion - Trithion - - .10 nd nd .25 nd nd .25 nd .1 .25 nd nd .50 nd nd .25 nd .04 .50 nd nd 40,000 2,000 145,000 57,000 nd 24,000 340 High nd Low do nd Low nd Corn, general 5.6 3.2 1.6 purpose. Citrus fruits 2.0 2.3 nr General purpose 5.2 3.6 2.8 Cotton and wheat 8.0 28 23 Not identified nr nr nr Wheat, corn, 8.5 9.5 6.6 sorghum. General purpose nr nr nr .3 nr 1.6 11 nr 4.0 nr 9.0 2.0 28 20 .1 5.0 .1 Chlorophenoxy and triazine herbicides Atrazine - - 2,4-D - - - 2,4,5-T- - - Silvex - - - .5 nd nd .5 *100 nd .5 *10 nd .5 nd nd 33,000 900,000 240,000 140,000 High Low Medium nd Corn 24 54 90 Wheat, rangeland, 4 31 38 general purpose. Rice, rangeland, .8 nr nr general purpose. Sugarcane, rice, nr nr nr rangeland. 76 23 .2 nr 92 60 2.2 .4 Detection limits shown are for water samples. Bed-sediment reporting limits are 10 times greater and are expressed in units micrograms per kilogram (Lucas and others, 1980). All criteria are from U.S. Environmental Protection Agency (1980), except for values marked by asterisks, which are from U.S. Environmental Protection Agency (1976). The human-health criteria for all pesticides except endrin, lindane, methoxychlor, 2,4-D, and 2,4,5-T represent the estimated average concentrations associated with an incremental increase in cancer risk of 10" (one additional cancer per 100,000 people over a lifetime of exposure). The aquatic-life criteria are for freshwater and are 24-hour average concentrations. 3 Data from Kenaga and Goring (1980). Relative persistence within each pesticide group as estimated from Hiltbold (1974) and Wauchope (1978). 5 Data for 1966, from Eichers and others (1970); for 1971, Andrilenas (1974); for 1976, Eichers and others (1978); for 1982, U.S. Department of Agriculture (1983). Data for 1982 do not include use on livestock or use in California, Colorado, Connecticut, Maine, Massachusetts, Nevada, New Hampshire, New Jersey, New Mexico, Oregon, Rhode Island, Utah, Vermont, West Virginia, and Wyoming. t Data from Mark H. Glaze (U.S. Environmental Protection Agency, written commun., 1983). See footnote 2. National Water Summary 1984 Water-Quality Issues 89 Table 7. Summary of detections of pesticides in water and bed sediments at the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Monitoring Network stations, 1975 to 1980 Water Stations Chemical Number monitored Percentage with detections Samples Number collected Bed material Stations Percentage with Number detections monitored Percentage with detections Samples Number collected Percentage with detections Organochlorine insecticides Aldrin - - - - Dieldrin - - - Chlordane - - ODD- - - - - DDE- - - - - DDT- - - - - Endrin - - - - Heptachlor epoxide - - - Lindane - - - Methoxychlor - Toxaphene - - 177 177 177 177 177 177 180 177 177 172 177 2.3 2.3 .6 4.0 .6 2.8 1.1 4.5 8.5 .0 2.8 2,946 2,945 2,943 2,720 2,715 2,721 2,950 2,946 2,945 2,761 2,946 0.2 .2 .0 .3 .0 .4 .1 .3 1.1 .0 .4 171 172 171 171 172 171 171 171 171 160 171 2.9 29 30 31 42 26 2.3 5.3 .6 .6 3.5 1,015 1,017 1,014 990 989 992 1,015 1,017 1,018 941 1,014 0.6 12 9.9 12 17 8.5 .6 1.0 .1 .1 .6 Organophosphate insecticides Diazinon - - - Ethion - - - - Malathion - - Methyl parathion - - Methyl trithion - - - Parathion- - - Trithion - - - 174 174 174 174 174 174 174 9.8 .6 .6 2.7 .0 .6 1.1 2,859 2,823 2,859 2,861 2,822 2,856 2,819 1.2 .1 .1 .1 .0 .0 .1 164 163 163 163 163 163 163 1.2 .6 .0 .0 .0 .0 .0 929 928 929 929 928 928 925 .2 .4 .0 .0 .0 .0 .0 Chlorophenoxy and triazine herbicides Atrazine - - - 2,4-D - - - - 2,4,5-T- - - - Silvex - - - - 144 186 186 167 24 2.4 .6 .6 1,363 1,764 1,765 1,768 4.8 .2 .1 .1 126 142 142 142 .0 1.4 .7 1.4 347 487 486 488 .0 .4 .2 .4 90 National Water Summary 1984 Hydrologic Perspectives similarly located in both programs, the earlier data for the western rivers showed an average frequency of detection from 1968 to 1971 of about 12 detections per 100 water samples (using Pesticide Monitoring Network detection limits), compared to an average of less than 1 detection per 100 samples during the period from 1975 to 1980 in the Pesticide Monitoring Network. Trends also were evaluated statistically for each chemical at every station where at least 2 water samples out of 10 or 2 bed-material samples out of 6 contained detectable amounts of pesticides. There were only enough detec- tions in water samples to evaluate trends for 13 out of about 2,000 possible station-chemical combinations. Trends in bed-material levels, however, were testable for 123 station-chemical combinations. Statistically significant (a = 0.30) trends in pesticide concentrations in bed- material were found for 36 station-chemical combinations, with 7 increasing trends and 29 decreasing trends. These trends were concen- trated at relatively few stations. Trends were most often apparent for the chemicals most frequently detected ODD, DDE, DOT, chlordane, and dieldrin. Of the seven increasing trends nationwide, five occurred at the Black River at Kingstree, S.C., which had increasing trends in ODD, DDE, DOT, chlordane, and dieldrin. Of the 29 decreasing trends nationwide, 18 occurred at only 6 stations, and the remaining 11 were at 11 different stations. ORGANOPHOSPHATE INSECTICIDES Use and Occurrence Farm use of the organophosphate insecti- cides that were monitored has declined steadily through the 1970's, though not as dramatically as the use of organochlorine insecticides (fig. 51, table 6). Only the total use of diazinon has been increasing. Methyl parathion was used most often, mainly on cotton. Some of the other chemicals monitored ethion, methyl trithion, and trithion were used very little on farms during the time the Pesticide Monitoring Network was in existence. Frequencies of detections of organophos- phate insecticides, as with the organochlorine insecticides, reflect the combined effects of variable detection limits, amount of use, solu- bility, and persistence. The low frequency of detections probably results primarily from the relatively high detection limits for these chemi- cals and their low persistence. Methyl parath- ion was the most heavily used organophosphate insecticide and yet was detected in only 3 of almost 2,900 water samples. Other chemicals in the group with detection limits equal to or higher than methyl parathion and with less use were detected in even fewer water samples. Diazinon was detected substantially more often than the other organophosphate chemicals in water, but there were only 34 detections in 2,859 samples (1.2 percent). The detection limit for diazinon is less than one-half of that of the other chemicals in this group, and it is more persistent than the other organophosphate compounds. In bed material, organophosphate chemicals were almost never detected due to their high solubility in water and low persist- ence. Trends Over Time No trends are evident in detections of or- ganophosphate insecticides on a national scale (fig. 53) or regional scale or at any individual station for either water or bed material. Detec- tions were too few to allow any analysis of trend in bed-material concentrations. Only six bed-material detections were made at a total of three stations. On a station-by-station basis for all organophosphate chemicals, sufficient num- bers of detections in water samples were made to test trends for only seven station-chemical combinations, and no significant trends were evident. CHLOROPHENOXY AND TRIAZINE HERBICIDES Use and Occurrence The use of herbicides has rapidly increased during the past 20 years (fig. 51), with atrazine and 2,4-D accounting for much of the increase. From 1971 to 1976, these two chemicals ac- counted for about 50 percent of all herbicide use, but the dominance of these chemicals had decreased somewhat by 1980; for example, atrazine fell from 41 percent of total herbicide application on corn in 1976 (Eichers and others, 1978) to 33 percent in 1980 (Hanthorn and others, 1982). Data from the Pesticide Monitoring Net- work show virtually no detections of herbicides 1976 1977 1978 1979 1980 Figure 53. Frequency of detection of organophos- phate insecticides in water samples from stations in the U.S. Geological Survey-U.S. Environmental Protection Agency Pesticide Monitoring Network, 1975 to 1980. National Water Summary 1984 Water-Quality Issues 91 in bed material and, except for atrazine, few detections in water samples (table 7). For most stations, herbicides were measured for only 3 years (1976-78). The second most detected herbicide after atrazine was 2,4-D. These find- ings may be explained by the extremely heavy use of atrazine and 2,4-D, combined with the greater persistence of atrazine (table 6). All stations at which atrazine was detected more than two times are located downriver from major corn-growing areas where virtually all atrazine is applied. Trends Over Time The generally low rate of detections of herbicides, as well as the limited time span of data available for the triazine herbicides made it impossible to evaluate trends meaningfully in either bed sediments or water samples. CONCLUSIONS Concentrations of chlorinated hydrocar- bon insecticides, including dieldrin, chlordane, and DOT, have decreased in both the water and bed material of major United States rivers since the mid-1970's, when their use was greatly cur- tailed. No clear trends are evident in concentra- tions of the organophosphate insecticides and herbicides that were monitored. From 1975 to 1980, fewer than 10 percent of almost 3,000 water samples and fewer than 20 percent of nearly 1,000 bed-material samples contained detectable levels of any of the 22 common pesticides monitored. The small num- ber of detections is due partly to the difficulties of sampling and measuring the very low con- centrations of pesticides that generally are pres- ent. Although analytical detection limits were not sensitive enough to determine if concentra- tions exceeded established water-quality criteria, the low frequency of detections sug- gests that the 22 pesticides that were monitored do not occur in many rivers at concentrations that consistently far exceed water-quality criteria. The low and variable frequency of detec- tion of the pesticides, regional patterns of use, and the constantly changing array of available pesticides make national-scale monitoring of pesticides a very difficult undertaking. Pesti- cide use tends to be strongly regional, with most use of each chemical occurring in only one or two regions of the country; for example, most DOT and toxaphene were applied in cotton- growing areas, and most atrazine was applied in corn-growing areas. The types of pesticides used are changing constantly; new chemicals are being introduced each year, and others are being discontinued. Each different type of chemical presents unique sampling and analysis problems. Future pesticide-monitoring efforts will need to respond to changes in the types of pesticides, methods of application, chemical characteristics, and geographic patterns of use. Analytical methods will need to be developed and improved, and different types of monitor- ing approaches will need to be applied. As our knowledge about pesticide chemicals and their behavior in the environment increases, efforts to monitor the levels, trends, and geographic distribution of pesticides gradually will become more sophisticated and effective. SELECTED REFERENCES Andrilenas, P. A., 1974, Farmers use of pesticides in 1971 Quantities: U.S. Department of Agricul- ture, Agricultural Economic Report No. 252, 56 p. Dahm, P. A., 1970, Chemistry and metabolism of insecticides, in Willrich, T. L., and Smith, G. E., eds., Agricultural practices and water quality: Ames, Iowa State University Press, p. 167-182. Eichers, T. R., Andrilenas, P. A., Jenkins, Robert, and Fox, A. S., 1968, Quantities of pesticides used by farmers in 1964: U.S. Department of Agriculture, Agricultural Economic Report No. 131, 37 p. Eichers, T. R., Andrilenas, P. A., Black, Helen, Jenkins, Robert, and Fox, A. S., 1970, Quanti- ties of pesticides used by farmers in 1966: U.S. Department of Agriculture, Agricultural Eco- nomic Report No. 179, 61 p. Eichers, T. R., Andrilenas, P. A., and Anderson, T. W., 1978, Farmers use of pesticides in 1976: U.S. Department of Agriculture, Agricultural Economic Report No. 418, 58 p. Feltz, H. R., Sayers, W. T., and Nicholson, H. P., 1971, National monitoring program for the assessment of pesticide residues in water: Pesti- cides Monitoring Journal, v. 5, no. 1, p. 54-59. Gilliom, R. J., Alexander, R. B., and Smith, R. A., 1985, Pesticides in the Nation's rivers, 1975-1980, and implications for future moni- toring: U.S. Geological Survey Water-Supply Paper 2271. [In press.] Hanthorn, Michael, Osteen, Craig, McDowell, Robert, and Roberson, Larry, 1982, 1980 pesti- cide use on field corn in the major producing states: U.S. Department of Agriculture, Natural Resource Economics Division, Report No. AGES820202, 33 p. Hiltbold, A. E., 1974, Persistence in pesticides in soil, in Guenzi, W. D., ed., Pesticides in soil and water: Madison, Wise., Soil Society of America, p. 203-222. Kenaga, E. E., and Goring, C. A. I., 1980, Relation- ship between water solubility, soil sorption, octanol-water partitioning, and concentration of chemicals in biota, in Eaton, J. G., Parish, P. R., and Hendricks, A. C., eds., Aquatic 92 National Water Summary 1984 Hydrologic Perspectives toxicology: American Society for Testing and Materials, ASTM STP 707, p. 78-115. Lucas, D., and others, 1980, Recommendations for the national surface-water monitoring pro- gram report two: U.S. Environmental Protec- tion Agency, Report RTI/1864714/01-011, Re- search Triangle Institute, 148 p. McDowell, Robert, Marsh, Cleveland, and Osteen, Craig, 1982, Insecticide use on cotton in 1979: U.S. Department of Agriculture, Economic Re- search Service Staff Report No. AGES 820519, 51 p. Schulze, J. A., Manigold, D. B., and Andrews, F. L., 1973, Pesticides in selected western streams, 1968-71: Pesticides Monitoring Journal, v. 7, no. 1, p. 73-84. U.S. Department of Agriculture, 1983, Inputs out- look and situation, October: Washington, D.C., U.S. Government Printing Office, 23 p. U.S. Environmental Protection Agency, 1976, Qual- ity criteria for water: Washington, D.C., U.S. Government Printing Office, 256 p. __1979, Fish kills caused by pollution: U.S. Envi- ronmental Protection Agency Report EPA- 440/4-78-011, 78 p. __1980, Water quality criteria documents Availability: U.S. Federal Register, v. 45, No. 231, p. 79318-79379. U.S. Geological Survey, 1984, National water sum- mary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. Wauchope, R. D., 1978, The pesticide content of surface water draining from agricultural fields A review: Journal of Environmental Quality, v. 7, no. 4, p. 459-472. National Water Summary 1984 Water-Quality Issues 93 OVERVIEW OF THE OCCURRENCE OF NITRATE IN GROUND WATER OF THE UNITED STATES By Robert J. Madison and Jilann O. Brunett INTRODUCTION Nitrate and other nitrogenous compounds are essential elements in the life processes of plants and animals. In spite of its importance, nitrate is a potentially hazardous pollutant when present in drinking water at sufficiently high concentrations (U.S. Environmental Pro- tection Agency, 1982) 1 . Although nitrate in itself is relatively nontoxic, it can be reduced bacterially to nitrite in the intestines of new- born infants and may result in the disease methemoglobinemia. Infant mortality from methemoglobinemia is rare where nitrate-nitro- gen concentrations in drinking water are less than 10 milligrams per liter (mg/L), but its incidence increases with increasing concentra- tions (Walton, 1951). Nitrite also can react with other substances, such as amines, in the stomach or lungs to form N-nitrosoamines, which have been found to induce tumors in laboratory animals. Although no human tu- mors have been linked directly to these com- pounds, exposure to the compounds may pose a risk of human cancer (National Research Coun- cil, 1978, p. 3). Most natural waters that are unaffected by human-related activities contain less than 10 mg/L nitrate-nitrogen (Feth, 1966, p. 49) though, in some arid areas, natural concentra- tions may be greater. As discussed later in this article, nitrate-nitrogen concentrations greater *han about 3 mg/L may be indicative of human sources. A survey of relevant publications indi- cates that in many areas of the Nation, human sources of nitrogen have resulted in concentra- *ions of nitrate-nitrogen that are well above 3 mg/L in ground water, especially in shallow aquifers. Freeze and Cherry (1979, p. 413) stated that dissolved nitrogen in the form of nitrate is the most common contaminant of aquifer systems. The severity of nitrate con- ^amination on a national scale, however, has lot been well documented. In a recent assessment of nitrate in the environment, the National Research Council '1978, p. 465) concluded that the present ambi- ent levels of nitrate in the United States rarely In this discussion nitrate concentration is expressed in terms of its equivalent elemental nitrogen (N) content. Some investigators may "eport nitrate content in terms of nitrate ion (NO -). Nitrate content expressed as nitrate ion can be converted to its equivalent elemental nitrogen content by dividing by 4.43; for example, 44 mg/L nitrate on is equivalent to about 10 mg/L nitrate-nitrogen. have been reported to affect adversely the health of humans or livestock. However, rapid population growth and associated human ac- tivities may aggravate nitrate-pollution prob- lems in the future. In States where nitrate contamination of ground water has been identified, reconnais- sance surveys and mass-balance studies that attempt to account for the total input and output of nitrogen in individual aquifers or areas have been accomplished. Many of these studies show qualitative relations between high nitrate concentration in ground water and known or suspected nitrogen sources. Several studies have used nitrogen-isotope analysis with some success to infer the sources of nitrate in ground water. In southern Delaware, for exam- ple, Ritter and Chirnside (1984) used nitrogen- isotope ratios in combination with land use information to distinguish between fertilizer nitrogen, animal- or human-waste nitrogen, and natural soil nitrogen. Similar results with isotope ratios have been reported for high- nitrate waters in Texas, Nebraska, and New York (Kreitler and others, 1978; Kreitler and Jones, 1975; Gormly and Spalding, 1979). However, a search of the current literature revealed no studies that summarized the occur- rence and distribution of elevated concentra- tions of nitrate in ground water on a nationwide scale. The purpose of this discussion is to provide a general overview of the occurrence of high- nitrate concentration; to delineate those areas of the country where nitrate contamination of ground water may be, or has the potential for becoming, a regional problem, and to discuss the major sources of nitrate in soils and ground water. SOURCES AND TRANSPORT OF NITROGEN Nitrate can enter the ground-water system from a variety of natural and human sources. The principal natural sources are soil nitrogen, nitrogen-rich geologic deposits, and atmospher- ic deposition. Principal human-related sources and contributory activities include fertilizers, septic tank drainage, feedlots, dairy and poul- try farming, land disposal of municipal and industrial wastes, dry cultivation of mineralized soils, and the leaching of soil as the result of the 94 National Water Summary 1984 Hydrologic Perspectives application of irrigation water. Regardless of the source, the amount of nitrate that enters the ground water is con- trolled by a complex set of hydrologic, chemi- cal, and biological processes that take place in the subsurface environment (fig. 54). The sim- plified diagram in figure 55 illustrates the fol- (Denitrification in reducing zones) Figure 54. Sources, move- ment, and reaction of nitro- gen in soils and ground water. (Chemical symbols: N, elemental nitrogen; N2, nitrogen gas; N2O, nitrous oxide; NO2~, nitrite; NO3~, nitrate; NH 3, ammonia, NH4+ , ammonium; N 2(aq), nitrogen gas; dissolved in water. (Source: Modified from Freeze and Cherry, 1979, p. 414.) Figure 55. Simplified biologi- cal nitrogen cycle, showing some environmentally im- portant reactions of nitro- gen. Other biological reac- tions evolving nitrogen also occur. (Source: Modified from National Research Council, 1978, p. 23.) Heterotrophic conversion lowing major transformations of nitrogen that can take place (commonly referred to as the nitrogen cycle): 1. Assimilation of inorganic forms of nitrogen (ammonia and nitrate) by plants and microorganisms. 2. Heterotrophic conversion of organic nitrogen from one organism to another. 3. Ammonification of organic nitrogen to produce am- monia during the decomposition of organic matter. 4. Nitrification of ammonia to nitrite and nitrate by the chemical process of oxidation. 5. Denitrification (bacterial reduction) of nitrate to nitrous oxide (NO) and molecular nitrogen (N2) under anoxic conditions. 6. Fixation of nitrogen (reduction of nitrogen gas to am- monia and organic nitrogen) by microorganisms. The operation of the nitrogen cycle con- trols the amount of nitrate produced in the soil column, primarily as a result of nitrification, but the concentration at any one place can vary widely depending on environmental conditions. Most nitrogen compounds appear to move freely through aquifers without much change in their total concentrations. An exception is ammonium ions (NH4 + ) which may be ad- sorbed on clay minerals. The rate of movement of nitrate through the soil column and the amount that is ultimately "leached" to the ground water are controlled primarily by the soil type and its hydraulic conductivity. Other factors include soil moisture, temperature, vegetation or crop type, and precipitation. In saturated soils, the main factors limiting water movement are the size and continuity of pores in the soil. Generally, as average intersti- tial pore size increases, the hydraulic conduc- tivity and, thus, the potential for water move- ment increase. Hydraulic conductivity values for saturated uniform-grain size sandy soils can be several hundred times greater than corre- sponding values for clay soils or soils with heterogenerous mixtures of grain sizes. Thus, clean sandy soils will transmit more water and Organic compounds containing nitrogen Ammonification^ Assimilation Ammonium (NH4+ ) i Nitrification Assimilation Nitrite (N02 -» i of nitrogen / into / organic compounds Nitrification Assimilation Nitrate <N03 } of nitrogen organic compounds or denitrification / Denitrification / Nitrogen gas (No) I/ r Denitrifi- cation \ t Nitrous oxide (N20| National Water Summary 1984 Water-Quality Issues 95 more dissolved materials, but they provide less opportunity of the dissolution of nitrates than the fine-grain or organic-rich soils. As soils dry out, the hydraulic conductivity and, thus, the rate of soil-water movement decrease rapidly. At a pressure of 1 atmosphere, the hydraulic conductivity of an unsaturated soil can be as little as one hundred thousandth of the value for the same soil when saturated (National Research Council, 1978, p. 107). A detailed discussion of the rate of nitrate leaching in soils for various geographic areas of the United States can be found in Thomas (1970, p. 1-20). NITRATE LEVELS IN GROUND WATER The level of nitrate concentration that is considered to be above natural or background levels and, thus, the result of human activities, has not been clearly defined. Nitrate-nitrogen concentrations in most unpolluted ground waters seldom exceed 10 mg/L (Feth, 1966, p. 49). In a few isolated areas of naturally occurring nitrate-rich deposits, however, values on the order of several hundred milligrams per liter have been found (Hendry and others, 1984, p. 185). To obtain a national perspective on the extent of elevated nitrate concentrations in ground water for the National Water Summary, existing data were evaluated for human-related influences. Based on this evaluation, a concentration of more than 3 mg/L was arbitrarily defined as indicating possible human inputs. The U.S. Geological Survey's National Water-Data Storage and Retrieval System (WATSTORE) contains nitrate analyses for about 87,000 wells throughout the United States. Nitrate data from this computerized data base represent samples collected and analyzed over a period of 25 years. The data, which were analyzed statistically to see if regional areas of elevated nitrate concentrations could be reason- ably portrayed from existing data, were separated into four ranges of nitrate-nitrogen concentrations: Less than 0.2 mg/L Assumed to represent natural background concentrations. 0.21 to 3.0 mg/L Transitional; concentrations that may or may not represent human influence. 3.1 to 10 mg/L May indicate elevated concentrations resulting from human activities. More than 10 mg/L Exceeds maximum concentration in National Interim Primary Drinking-Water Regula- tions (U.S. Environmental Protection Agency, 1982). Because few data for Texas were available in WATSTORE, the Texas Natural Resources Infor- mation System (TNRIS) of the Texas Department of Water Resources also was used in the anal- ysis. This data base contains water analyses from more than 36,000 wells, including about 5,000 public-supply wells. The frequency distribution of the data for the four categories defined above are shown in table 8. Those areas where more than 25 per- cent of the wells (for which nitrate data are available) had water with a maximum nitrate- nitrogen concentration exceeding 3.0 mg/L are outlined in figure 56. Figure 56 should be interpreted with caution. The data bases used to compile figure 56 do not necessarily repre- sent a random or unbiased sample of all wells or aquifers in the United States inasmuch as the data were collected to meet many different objectives; thus, the types of wells sampled, the numbers of wells, the time period covered, and the areal coverage of sampling networks differ from State to State and within a State. In locations where problems related to nitrate in water are known to exist, the density of sam- pling may be higher than in nonproblem areas. Little information was available for areas in some States because existing data were not in a machine-readable form or because ground wa- ter is not yet important enough to warrant the expense of water analysis. For the rest of the country, the data base contained water analyses from at least five wells in most counties. Be- cause of these biases in the data, figure 56 should not be used to imply that more than 25 percent of all unsampled wells in any shaded area also will have elevated nitrate values. The data do indicate, however, that human activi- ties have elevated the nitrate-nitrogen levels in ground water above 3 mg/L in many areas of the United States. Of the nearly 124,000 wells for which ni- trate values are available, more than 24,000 (20 percent) had water with maximum nitrate- nitrogen concentrations higher than 3 mg/L. However, only about 8,200 of these wells (6 percent) had water with maximum nitrate- nitrogen concentrations that exceeded 10 mg/L, the criterion for drinking waters as established by the U.S. Environmental Protec- tion Agency (1982). In most instances, elevated nitrate concen- trations were found in water from relatively shallow wells (less than 100 feet). The relations between nitrate concentrations and well depth for the data analyzed in this study are shown in figure 57. Water samples with more than 3 mg/L nitrate-nitrogen tended to be less com- mon with increasing depth of the sampled wells. This inverse relation of nitrate concen- tration to well depth has been documented by many investigators (for example, see Spruill, 1983, p. 977-81). Wells that yielded water samples with less than 3 mg/L nitrate-nitrogen had a depth distribution similar to that of all the wells sampled, supporting the assumption of 3 mg/L as a break point between human- 96 National Water Summary 1984 Hydrologic Perspectives Table 8. Summary of nitrate-nitrogen concentrations in ground water, by State [Percentages for each State may not add to 100 percent because of independent Founding; mg/L = milligrams per liter. Source: Data from samples collected and analyzed by the U.S. Geological Survey and Texas Department of Natural Resources over a period of 25 years State Alabama - - - - Alaska - - - - - Arizona - - - - Arkansas - - - - California - - - Colorado - - - - Connecticut- - - Delaware - - - - Florida ----- Georgia - - - - Hawaii ----- Idaho ----- Illinois ----- Indiana- - - - - Iowa- ----- Kansas ----- Kentucky - - - - Louisiana- - - - Maine ----- Maryland- - - - Massachusetts - - Michigan - - - - Minnesota - - - Mississippi - - - Missouri - - - - Montana - - - - Nebraska - - - - Nevada- - - - - New Hampshire - New Jersey - - - New Mexico- - - New York - - - North Carolina - North Dakota - - Ohio- ----- Oklahoma - - - Oregon- - - - - Pennsylvania - - Puerto Rico - - - Rhode Island - - South Carolina - South Dakota - - Tennessee- - - - Texas ----- Utah- ----- Vermont - - - - Virginia - - - - Washington- - - West Virginia - - Wisconsin - - - Wyoming- - - - Total or percentage - - Number of wells sampled 244 1,305 4,164 2,436 2,732 5,492 348 165 3,140 1,137 164 1,806 359 650 4,088 1,140 3,227 3,177 147 1,521 414 1,108 1,655 1,701 2,165 2,821 2,326 465 69 1,385 4,685 2,491 908 7,387 339 1,724 685 4,326 79 171 557 1,996 109 36,196 3,301 73 762 1,158 954 2,727 1,477 123,656 Percentage of wells for which maximum nitrate-nitrogen concentration fell within indicated range (mg/L) 0-0.2 47.1 60.9 12.1 49.1 21.9 33.8 33.6 34.5 71.5 66.7 15.9 33.3 56.0 55.4 44.9 17.0 36.5 78.3 50.3 40.9 42.3 79.1 39.1 76.5 64.2 43.4 18.0 46.2 66.7 63.0 38.4 28.9 72.1 22.4 61.7 23.0 57.1 31.1 16.5 17.0 69.3 49.2 65.1 39.1 52.1 70.7 38.3 68.6 40.1 47.9 0.21-3.0 45.5 33.9 49.7 38.5 45.4 43.3 49.7 30.9 24.2 28.5 75.0 52.0 30.1 33.4 36.7 28.8 46.2 19.4 35.4 30.4 52.2 17.1 40.7 21.7 27.2 45.1 49.3 45.4 29.0 25.6 48.9 30.8 22.0 68.5 90 R Z".o 41.2 36.4 38.7 48.1 38.0 26.6 35.9 29.4 < 76.5 > 50.4 41.1 25.9 38.9 25.9 41.3 40.7 < 80.4 > 3.1-10 7.4 2 0 .0 24.4 8.5 22.5 17.2 14.4 25.5 2.3 4.3 9.1 12.9 5.6 9.7 13.4 34.2 13.0 1.8 12.2 22.0 4.3 2.8 10.9 1.6 6.6 7.7 23.4 7.5 2.9 10.0 9.8 29.3 5.1 4.4 5.9 24.1 5.4 24.4 32.9 8.8 3.4 8.2 4.6 14.1 8.4 5.5 2.6 18.6 5.0 15.1 7.6 13.2 More than 10 0.0 2.4 13.9 3.9 10.1 5.7 2.3 9.1 2.0 .5 .0 1.7 8.4 1.4 5.0 20.0 4.2 .6 2.0 6.8 1.2 1.1 9.3 .2 2.1 3.8 9.3 .9 1.4 1.4 2.9 11.0 .8 4.6 2.6 11.8 1.2 5.9 2.5 36.3 .7 6.7 .9 9.4 2.0 1.4 .8 4.3 .5 3.6 3.8 6.4 National Water Summary 1984 Water-Quality Issues 97 «». HAWAII ALASKA EXPLANATION Nitrate-nitrogen concentration Water samples exceeded 3 mg/L in: * ' 25 percent or more of sampled wells Fewer than 25 percent of sampled wells PUERTO RICO Fewer than 5 wells per county in data base Figure 56. Nitrate-nitrogen distribution in ground water of the United States and Puerto Rico. Delineation is based on whether or not the concentration of nitrate-nitrogen in water exceeded 3 milligrams per liter (mg/L) in 25 percent of sampled wells in each county. The 3-mg/L concentration was selected for the purpose of the 1984 National Water Summary as the approximate concentration beyond which human activities could be contributing nitrogenous compounds to the ground water. It should be noted that concentrations of 3 mg/L or more also can occur naturally, especially in the semiarid West. In most of the area shown on the map, water with less than 3 mg/L nitrate-nitrogen may be available from different parts of the same aquifer. The data represent samples collected and analyzed over the past 25 years. See table 8 for number of wells sampled in each State and text for additional interpretation of map data. (Data were compiled by R. J. Madison and J. O. Brunett from U.S. Geological Survey and Texas Department of Water Resources data.) and natural-nitrate influences. Because most nitrate sources are at the land surface or in the soil column, it would be expected that shallow aquifers would be more susceptible to contami- nation than deeper aquifers. Nitrate contami- nation of deeper ground water can occur, how- ever, where a hydraulic connection and down- ward hydraulic gradient exist between shallow and deep aquifers and where sufficient time has elapsed for the contaminants from shallow sources to migrate to the deeper zones (Peri- mutter and Koch, 1972, p. B22). MAJOR SOURCES OF ELEVATED NITRATE CONCENTRATIONS The major sources of potential nitrate con- tamination include septic systems, agricultural activities (fertilizers, irrigation, dryland farm- ing, and livestock wastes), land disposal of wastes, industrial wastes, and a variety of natu- ral sources. These sources are summarized below, and specific case studies are used to illustrate the present extent and possible region- al significance of elevated nitrate concentra- tions. SEPTIC SYSTEM DISCHARGES Septic tanks and shallow drain fields are the principal method for the disposal of domes- tic wastes from about 25 percent of the year- round housing units in the United States (U.S. Bureau of the Census, 1982, p. 754). The estimated nitrogen content of wastes delivered annually to septic tanks is about 6 percent of the total nonpoint-nitrogen-pollution load (Na- tional Research Council, 1978, p. 263). The effluent from a typical septic tank may contain 98 National Water Summary 1984 Hydrologic Perspectives 80 60 u_ O LLJ 3 40 20 Total wells sampled Water with less than 3 mg/L N03 Water with Water with greater 3.1-10 mg/L N03 than 10 mg/L No3 Nitrate-nitrogen concentration EXPLANATION Total well depth, in feet Less than 100 101-200 201-300 Greater than 300 Figure 57. Distribution of three ranges of nitrate- nitrogen concentrations (milligrams per liter) in well water with well depth. About 124,000 wells were included in analysis. (Source: Compiled by R. J. Madison and J. O. Brunett from U.S. Geological Sur- vey and Texas Department of Water Resources data.) as much as 70 mg/L nitrogen, primarily in the form of ammonia and organic nitrogen, which is nitrified and moves into the ground water as nitrate. Local nitrate contamination, such as that caused by effluent from a single disposal system entering a well in the immediate vicinity, can occur almost anywhere. More extensive prob- lems occur in urban or suburban areas where a high density of individual septic systems con- tributes large quantities of wastes, with the potential to contaminate large parts of water- supply aquifers. Discharge from septic tanks was identified as one of the more prevalent sources of ground-water contamination and elevated ni- trate concentrations in the Northeastern United States (Miller and others, 1974). In the 11 States reported on in that study, 12 million people (23 percent of the total population) used septic systems that discharged as much as 0.5 to 1 billion gallons per day (bgd) of raw sewage to the subsurface. In addition to describing sever- al regional ground-water quality problems, the report stated that cases of contamination from individual onsite disposal systems probably number in the thousands. Several comprehensive studies of the ef- fects of individual sewage-disposal systems on ground-water quality have been carried out on Long Island, N.Y. (Perlmutter and Koch, 1972; Katz and others, 1980; Porter, 1980). Perlmut- ter and Koch (1972, p. B225-B235) concluded that the two main sources of nitrate contamina- tion of the aquifers in southern Nassau County were sewage from several hundred thousand active or abandoned septic systems and leachate from chemical fertilizers. Nitrate-nitrogen in ground water in many parts of the study area approached or exceeded the drinking water limit of 10 mg/L. Nitrate-nitrogen concentra- tions in the upper aquifer, based on 200 ran- domly located wells, averaged about 6.3 mg/L and, in several places, exceeded 22.5 mg/L. A major concern was that water from the upper aquifer had moved downward into the underly- ing Magothy aquifer, forming a body of nitrogen-enriched water that occupied nearly the full thickness of the aquifer in parts of the study area. The Magothy aquifer is a principal source of public water-supply wells. During the period from 1952 to 1969, 72 of 234 public- supply wells for which long-term records are available showed statistically significant in- creases in nitrate concentration. Perlmutter and Koch concluded that if the trend present in 1969 continues, the nitrate concentration of water from 40 to 50 public-supply wells may exceed the 10 mg/L drinking water limit within the next 50 years. From a comparison of sew- ered and unsewered areas, they also concluded that improvement in the quality of chemically deteriorated ground water after construction of sanitary sewers is a slow process. Several decades may be required for effective natural dilution and discharge of most of the residual nitrate. Other areas where regional problems from septic systems have been reported include the Boston, Mass., suburban area, Los An- geles, Calif., Dade County, Fla., and the States of Delaware and Connecticut (Miller, 1980, p. 196-198). AGRICULTURAL ACTIVITIES Agricultural activities are the largest non- point sources of elevated nitrate concentrations in ground water. Nitrate in ground water under agricultural land results from a variety of land use practices and can originate from several sources. A search of the scientific publications revealed reports of investigations of nitrate contamination from agricultural activities for almost every State in the country. Fertilizers The use of chemical fertilizers has grown rapidly in the United States since the end of World War II. During the period from 1950 to 1970, fertilizer use in the United States dou- bled, from 20 million to 40 million tons per year (Miller, 1980, p. 431). During this same period, the percentage of nitrogen in all fertilizers used increased from 6.1 to 20.4 percent. The two National Water Summary 1984 Water-Quality Issues 99 areas of greatest fertilizer use in the United States are the Corn Belt (Iowa, Illinois, In- diana, and parts of adjacent States) and the Central Valley of California. The application of nitrogen fertilizers does not necessarily cause an increase in nitrate levels in ground water. However, in many places, the amounts applied exceed that re- quired by crops; this excess is available to be leached by natural precipitation or irrigation water. The actual amount of nitrate leached also depends on the types of crops grown; shallow-rooted crops such as potatoes require much heavier fertilization than do deep-rooted crops such as corn and must be irrigated more heavily. Saffigna and Keeney (1977) evaluated the nitrate and chloride concentration of ground water in a 650-square-mile (mi2) area of the central Wisconsin sand plains where about 25 percent of the irrigated cropland is planted in potatoes. Nitrate-nitrogen concentrations of ground water ranging from 4 to 23 mg/L were reported in the areas of cultivation, considera- bly above the values for well waters sampled in uncultivated areas. About 40 percent of the well waters sampled during this study had nitrate-nitrogen concentrations exceeding 10 mg/L. Measured chloride-nitrate ratios were relatively constant for all wells, suggesting that much of the nitrogen and chloride input to the ground water was from nitrogen and potassium (potassium chloride) fertilizers. Ground water beneath large areas of the Central Platte region of Nebraska reportedly had nitrate concentrations greater than the drinking water limit. Gormly and Spalding (1979, p. 291) reported that 183 of 256 ground- water samples collected from parts of Buffalo, Hall, and Merrick Counties during 1976 and 1977 contained nitrate-nitrogen in excess of 10 mg/L. The authors concluded, on the basis of measured nitrogen-isotope values, that the pri- mary source of contamination in most well waters was fertilizer. In various other surveys in Nebraska, 4,350 wells were sampled, 700 of which yielded water containing nitrogen con- centrations in excess of 10 mg/L. Eighty-two percent of the contaminated wells were affected by nonpoint sources, such as nitrogen fertilizer contained in irrigation return flow (Pye and others, 1983, p. 140). Irrigated Agriculture The use of irrigation water to expand crop production has increased substantially in the last century. In 1890, about 4 million acres were irrigated. By 1980, 58 million acres were irrigated (Solley and others, 1983, p. 16). As irrigation water moves through the soil profile, residual nitrate is leached. Because the permea- ble soils that commonly are irrigated have high leaching rates and high nitrification rates, ni- trate leaching can be a serious problem for many irrigated soils. As mentioned above, the source of the nitrate leached can be applied fertilizers. Naturally accumulated soil nitrate may be an equally important source, however, especially in the West. Although irrigation usage has been increas- ing in the Eastern United States, most of the irrigated land is still in the West; for example, in the Northeastern United States less than 1 percent of total cropland is irrigated (Solley and others, 1983, p. 18). According to a summary of ground-water contamination in the North- east, ground-water-quality problems resulting from irrigation practices are not as prevalent as those related to the application of fertilizers (Miller and others, 1974, p. 252). In many parts of the arid West, the soils are highly saline and not conducive to crop growth. To leach out unwanted salts and thus maintain soil salinity at tolerable levels for crop produc- tion, water applications must exceed plant requirements. The amount of irrigation water reaching the subsurface commonly is estimated to be 20 to 40 percent of the applied water. Where natural soil nitrogen has accumulated or where large amounts of fertilizer are applied, nitrate leaching can and does occur. California has the greatest percentage of cultivated land under irrigation in the United States; approximately 17 percent of the nation- al total (Solley and others, 1983, p. 18). The impact of irrigated agriculture on nitrate levels in ground water has been studied extensively in that State, especially in the Central Valley re- gion. Hull and others (1985) found well waters with elevated nitrate concentrations throughout the Sacramento Valley, which comprises the northern one-third of the Central Valley. They analyzed data from about 700 wells covering the period from 1912 to 1978. Under natural conditions, the maximum nitrate-nitrogen con- centration in well water was about 3 mg/L. They defined nitrate-nitrogen concentrations greater than 5.5 mg/L as "excessive," which indicated contamination due to human activi- ties. The percentage of wells with nitrate-nitro- gen concentrations greater than 5.5 mg/L in- creased from 2.2 percent between 1912 and 1913 to 4.9 percent for the decade, 1960 to 1969. The long-term increase accelerated sharply from 1974 to 1978, when 10.5 percent of 671 wells sampled had nitrate-nitrogen con- centrations exceeding 5.5 mg/L. Based on statistical analysis of 62 wells with long-term records, the authors concluded that water in nearly one-third of the wells in the Sacramento 100 National Water Summary 1984 Hydrologic Perspectives Valley may be undergoing a significant increase in nitrate concentrations. Except for urban areas in the Sacramento Valley, where the disposal of sewage wastes contributes to high nitrate concentrations, Hull and others (1985) found the major source of excessive nitrate in ground water throughout the Valley to be the leaching of fertilizers by irrigation water, primarily in orchard areas. The major physical factors contributing to the presence of excessive nitrate were good vertical flow in the soil profile, irrigation water derived primarily from ground-water pumping, and a water table that is moderately deep (more than 10 feet). Based on these factors, the areas identified as being susceptible to nitrate con- tamination cover roughly one-third of the Sac- ramento Valley. In the southern end of the Central Valley, especially in the San Joaquin Valley, the problem of high nitrate in irrigation drainage waters has prompted several intensive studies to determine the source of nitrate and methods of removing it (Federal Water Quality Administration, 1969). Dryland Farming Dryland farming, especially in the North- ern Great Plains, can lead to nitrate contamina- tion on a regional level. The crop-fallow rota- tion system of farming has reduced evapotran- spiration, allowing excess moisture to move down through the soil profile beneath the root zone. The region is underlain by geologic for- mations deposited in a marine environment, and the subsoil has a large supply of natural soluble salts, including nitrate. The shallow ground-water system is under- lain in many areas by poorly permeable shale. In the overlying glacial till above the shale, the percolating water forms a mound and moves downslope. As the ground water migrates from upland recharge areas to nearby discharge areas, it leaches the soluble salts and can ac- cumulate large quantities of dissolved solids in relatively short distances. The ground water eventually discharges at some stream channel or depression as a seep. The discharge water commonly has a dissolved-solids concentration in excess of 25,000 mg/L (Miller, 1980, p. 431). Significant concentrations of trace metals as well as high nitrate levels have been found in ground water in seep-prone areas, and nitrate poisoning of livestock from salinized ponds has been reported in a number of areas (Miller and Bergantino, 1983). Seep-affected areas in Mon- tana cover more than 200,000 acres; however, no reports were found that deal directly with nitrate contamination of ground water from these areas. The areas of saline seeps mapped by Miller and Bergantino (1983, p. 2) coincide closely with the areas of elevated nitrate con- centrations shown in figure 56. The leaching of natural soil nitrate after dryland farming also has been identified as one cause of excessive nitrate contamination of the ground water in Runnels County, Tex. (Kreitler and Jones, 1975, p. 53). LIVESTOCK AND POULTRY WASTES An increasing population and consequent increase in demands for meat and poultry products have resulted in a trend toward con- fined feeding of livestock. The largest areas of cattle feedlot operations are in southern California and Arizona, the Texas-Oklahoma Panhandles, the central Corn Belt, and from eastern Colorado through Nebraska to the North Dakota State line (National Research Council, 1978, p. 253). The major poultry- raising regions are in the Southern States and in the Delaware-Maryland area. In 1975, approxi- mately 10 million cattle were fed in operations with more than a 1,000-head capacity (Miller, 1980, p. 390). The National Research Council (1972, p. 20) estimated that animal wastes containing 6 million tons of nitrogen are pro- duced annually in the United States. In Dela- ware, one of the largest poultry-producing areas, about 140 million chickens are raised annually. The amount of waste they produce is estimated to be greater than the amount of solid waste produced by New York City (Liebhardt, 1972, p. 1). Miller (1980, p. 389) listed several primary mechanisms of ground-water contamination from animal feedlots and their associated treat- ment and disposal facilities: runoff and infiltra- tion from the feedlots themselves, runoff and infiltration from waste products collected and disposed of on land, and seepage or infiltration through the bottoms of waste lagoons. The rate of nitrate percolation to the ground-water table will depend on the quantity of nitrate formed, the hydraulic conductivity of the soil, and the amount of denitrification that takes place. Active feedlots reportedly have relatively low infiltration rates because of the puddled condi- tion of the soil, but, when the feedlot is taken out of use, the soil surface dries, nitrification is rapid, and significant leaching and downward percolation of nitrate may occur. Rapid leach- ing and infiltration also can occur when feed- lots are established on coarse-textured soil or if manure is removed frequently. Because confined feeding of livestock is a relatively new practice, few case histories of actual contamination of ground water are avail- able. Stewart and others (1968) evaluated am- monium and nitrate concentrations in ground water under feedlots and adjacent irrigated National Water Summary 1984 Water-Quality Issues 101 fields in Colorado and concluded that the feed- lots were a significant source of nitrate and ammonium in the ground waters. Mink and others (1976, p. 415) in a study of the land disposal of animal waste in the Boise Valley, Idaho, found that, due to denitrification, nitrate-nitrogen concentrations in the soil profile beneath two feedlots decreased rapidly from about 60 mg/L near the surface to 20 mg/L at the 6- to 7-ft depth. Where ground- water levels were less than 5 ft from the surface, the water was found to be affected by the feedlot. In a survey of high-nitrate ground water in Missouri, Keller and Smith (1967) analyzed water from more than 5,000 wells and springs. About 42 percent of the samples (12-75 percent for individual counties) contained more than 5 mg/L nitrate-nitrogen. They found the domi- nant source of nitrate in Missouri ground water to be nitrogenous waste from livestock feedlots. Chicken farms can present special prob- lems because of the high concentration of nitro- gen in the waste. Data from more than 800 well samples collected during a study of ground- water quality in Sussex County, Del., where millions of broilers are raised annually, re- vealed that the shallow water-table aquifer contains excessively high concentrations of ni- trate in several areas (Robertson, 1979). More than 20 percent of the wells sampled yielded water that exceeded the drinking water limit of 10 mg/L. The greatest incidence of high nitrate concentrations was associated with confined poultry-feeding operations. The average nitrate-nitrogen concentration in ground water sampled at chicken farms was 14 mg/L. LAND DISPOSAL OF MUNICIPAL WASTES In 1972, 571 communities in the United States with a total population of 6.6 million used land-disposal methods for municipal ef- fluents. Most were crop-irrigation systems located in the arid Southwest and in the East primarily in North and South Carolina (Nation- al Research Council, 1978, p. 259). Also, many municipalities in the West discharge effluents to infiltration basins in dry river beds. If the rates of application exceed the rate at which the soil or plants can assimilate nitrogenous com- pounds, nitrate contamination is a risk. Miller (1980, p. 230) estimated that approximately 2.3 bgd of effluent, some of which has received only primary treatment, is discharged onto the land. In a report on ground-water contamination in Arizona, California, Nevada, and Utah, Fuhriman and Barton (1971, p. 105) reported ground-water pollution problems in the vicinity of several municipal disposal facilities. In the Santa Cruz and Salt-Gila River basins of Arizo- na, waste water has been discharged to ephem- eral stream channels or used for irrigation for many years. The possibility of ground-water contamination from these disposal practices created a need for several monitoring programs to evaluate and trace the movement of the effluent (Schultz and others, 1976, p. 463). Nitrate-nitrogen concentrations in excess of 10 mg/L and as high as 28 mg/L were found in water from many wells. Maps of the water- quality data indicated that the ground-water areas with the highest chloride and nitrate concentrations tended to be associated with areas irrigated with sewage effluent. Because of a paucity of available data or reports, the actual local and regional extent of ground-water contamination that has occurred as the result of the land disposal of municipal wastes is difficult to evaluate. If the wastes receive effective secondary treatment before disposal, the potential for water-quality degra- dation, with the exception of nitrate contami- nation, probably is minimal (Miller, 1980, p. 227). Existing Federal and State regulations require that effluents discharged to land not degrade ground-water quality below nonpota- ble conditions. Where these regulations are followed or enforced, problems probably will not occur. However, Miller (1980, p. 230) concluded that only a part of the 2.3 bgd of effluent applied to the land has received pri- mary treatment or less-than-effective secondary treatment. INDUSTRIAL WASTES Although the contribution of nitrate to ground-water systems from industrial wastes is minimal compared to nonpoint sources such as agriculture, local impacts can be severe. The industrial process with the greatest potential for producing nitrogenous wastes is the synthesis of ammonia which is then used to produce other nitrogenous products such as fertilizers, nitric acid, urea, and paper products. Ammonia- nitrogen concentrations of more than 200 mg/L can occur in the waste streams of a typical ammonium-nitrate fertilizer plant (National Research Council, 1978, p. 270-273), and it has been estimated that a pulp mill with a capacity of 100 tons per day could produce wastes equivalent to the nitrogen load in the sewage from a city of more than 100,000 peo- pie. An example of the severity of contamina- tion that can occur in the vicinity of fertilizer plants is shown in a study by Naymik and Barcelona (1981). Chemical constituents leached from an uncovered chemical fertilizer bin at a plant in Illinois were drawn into the 102 National Water Summary 1984 Hydrologic Perspectives cone of depression of production wells and thus contaminated the underlying aquifer. The ground water in the interior of the contaminat- ed plume had ammonia concentrations as high as 2,100 mg/L and nitrate-nitrogen concentra- tions greater than 1,800 mg/L. As the plume moved downgradient, most of the ammonia was oxidized to nitrate rather than being lost by volatilization. This particular event involved a nitrate source not directly related to wastes from the production facility, but it does point out the potential for localized pollution where large quantities of nitrogenous materials are produced or concentrated. NATURAL SOURCES In addition to soil nitrogen, the major potential sources of natural nitrate in ground water are the accumulation of nitrate in caves (from bat guano and nitrogen-fixing bacteria) and in playas. Cave deposits have been report- ed in Indiana, Kentucky, Virginia, and Mis- souri (Viets and Hageman, 1971, p. 8), but their contribution to nitrate in ground water has not been well documented. The source that may be of most regional significance is the natural accumulation of nitrate by evaporation during the formation of playas in alluvial valleys in arid and semiarid parts of the country. This accumulation of nitrate in playas, along with high concentration of other dissolved salts, has been found in most of the drier parts of the Western States. In most areas unaffected by human activi- ties, playas probably do not contribute a large amount of nitrate to the ground water. Playas occur in areas where precipitation is low, sur- face drainage is impeded, and the land surface is underlain by materials that retard the down- ward movement of water. However, where conditions have been altered, such as the burial of ancient playa deposits, so that they are now in the zone of saturation, high nitrate ground water can result (Feth, 1966, p. 46). The occur- rence or severity of elevated nitrate in ground water resulting from these natural deposits is difficult to evaluate. They have been postulat- ed as a source of high nitrate in several studies, but their relative impact is difficult to assess because human sources also generally are pres- ent in the same areas. A recent investigation of ground-water quality in Paradise Valley, Ariz., indicated that high nitrate levels within specific areas of the valley may be of natural origin (Silver and Fielden, 1980, p. 244). Historical records indi- cate that nitrate-rich ground water (more than 100 mg/L nitrogen) occurred in the early 1900's before extensive development of the area. Moreover, high nitrate levels were found in ground water from fine-grained strata at depths as much as 1,000 ft, probably too deep to be affected by modern human activities. One possible source may have been ammonium chloride leached from volcanic tuffs in the nearby Superstition Mountains, subsequently oxidized to nitrate, and deposited in abandoned channels of an ancient braided-stream complex. Ground water with naturally occurring high nitrate concentrations also has been identi- fied in the Great Plains area of southern Alber- ta, Canada, just north of Montana. Hendry and others (1984, p. 185) found nitrate-nitrogen concentrations exceeding 300 mg/L in ground water from isolated enclaves below the water table in weathered glacial till. Cultivation of native soil (as discussed earlier for Montana) was not considered a reason for these high nitrate values. Through geochemical studies, environmental isotope studies, microbial ana- lyses, and laboratory experiments, they showed that the high nitrate is the result of the oxida- tion of ammonium present within the tills. It is postulated that the oxidation occurred when water tables were much lower than present-day levels. Naturally occurring nitrate, either in geologic deposits or in soils, existed in a general equilibrium with soil water and underlying ground water before human development. However, the potential for leaching and down- ward migration of natural nitrates with signifi- cant contamination of ground water, is consid- erable in some areas as the land is disturbed or as land use practices change. Research into the relation between fertilizer use and water quality in Nebraska has resulted in the discovery of large quantities of naturally occurring nitrate within the deep loess mantle of the southwest- ern and central parts of the State (Boyce and others, 1976, p. 93). The loess region includes more than 9,000 mi2, and the authors estimated that several million tons of nitrate in the loess is vulnerable to leaching. Data from soil cores in areas that previously had been irrigated showed that the nitrate had been leached. Because irrigation is expanding rapidly in the region, the potential for increased leaching and downward migration of nitrate from the soil, with result- ant nitrate contamination of aquifers, is of concern. PRESENT KNOWLEDGE AND FUTURE TRENDS The examples discussed above of increased nitrate levels in ground water and their poten- tial sources are but a few of the many cases reported in the hydrologic literature. In almost National Water Summary 1984 Water-Quality Issues 103 all cases, investigators have documented site- specific instances of ground-water contamina- tion and have postulated sources. At the pres- ent time, few data are available to quantify the amounts of nitrate contributed by a particular source, even at site-specific locations. A comprehensive review of nitrate in the environment, published by the National Re- search Council in 1978, contains detailed and well-documented evaluations of the present knowledge of the sources, transport, and fate of nitrate in air, water, and soil. The authors of that review concluded that the general qualita- tive relations between inputs, such as nitrogen fertilizer application rates, and crop yields are well known. However, the growth of a crop in a given location and the efficiency of its use of available nitrogen depend on soil properties, weather, climate, and cultivation and manage- ment practices. The interaction of these factors makes it difficult to predict how much nitrogen fertilizer a given crop needs at a given location or to determine the amount of residual nitrogen lost to the environment. The Council also concluded that, even at intensively studied sites, the complexities of soil, water, and nitrogen cycles have frustrated attempts to determine the quantitative contributions of specific sources of nitrate pollution. In an analysis of nitrogen- mass-balance models for two watersheds and for two statewide models, the Council found that a lack of adequate data, especially on nitrogen-cycle processes and leaching to the substrata was a major constraint to predictive modeling. Furthermore, soil characteristics, climatic factors, and agricultural practices are so heterogeneous that no quantitative general conclusions about the regional impact on water quality of a single factor, such as fertilizer application, could be supported. Current trends suggest that nitrate accumu- lations in ground water of the United States will continue to increase in the future. Several investigators have used historical data to docu- ment increasing nitrate levels in shallow aquifer systems. McDonald and Splinter (1982, p. 439), for example, evaluated data from 4,597 water samples from municipal ground- water supplies from all parts of Iowa. They showed that nitrate levels in ground water from wells less than 100 ft deep increased slowly, but steadily, between 1950 and 1979. Agricultural activities (including the disposal of animal wastes) and the disposal of human wastes are the two largest sources of nitrate contamination of ground water throughout the United States. Agricultural activities will increase as popula- tion increases and, thus, the potential for a continuation of these trends is present. Al- though future septic system discharges may decrease with increasing urbanization and the construction of public sewer systems, the ni- trate accumulated in the soil may be available for leaching for a significant period of time. In addition, natural dilution and discharge of human-induced nitrate in the affected ground water may take several decades (Perlmutter and Koch, 1972, p. 235). Although elevated concentrations of ni- trate are now most noticeable at shallow depths, long-term increases of nitrate levels in deeper wells are a possibility where the deeper aquifers are recharged by nitrogen-rich water from the shallow aquifers. The movement of drainage water through the unsaturated zone of many soils can be very slow, and the time required for present inputs of nitrogen to reach the ground-water reservoir may be many years. Because of this slow movement of recharge waters, contamination of deeper wells could continue for long periods, even if input sources of nitrogen decrease or are eliminated. At the present time, situations in which contaminated drinking water is the chief source of ingested nitrate generally are localized and the total population likely to be affected by nitrate-enriched water supplies probably is small (National Research Council, 1978, p. 598). However, the major human inputs of nitrate have occurred over the last 40 to 50 years. This is a short period of time in terms of ground-water movement in some aquifers, and one must consider that the total effects of existing inputs may not yet have occurred in many areas. TECHNIQUES FOR CONTROL The severity of future environmental im- pacts from nitrate accumulation in ground water will depend to a great extent on the development of cost-effective methodologies either to control the input sources of nitrates or to collect and treat wastes before they are dis- charged. Advanced treatment systems present- ly are available that can remove most of the nitrate and other nitrogen species from waste waters. However, they are costly, and their economic feasibility for treating large volumes of waste water has not been proved. Several cropland-management practices can reduce the amount of nitrate leaving the root zone and, thus, the amount available for leaching to the ground water. These include: Controlling use of irrigation water so that the amount of water applied is the minimum that is consistent with efficient crop production; Rotating crops that require high fertilization rates with those that require little fertilization or those that can utilize residual nitrogen from previous plantings; 104 National Water Summary 1984 Hydrologic Perspectives Adjusting the amount and timing of fertilizer applications to match the nitrogen uptake of plants and, thus, minimize the leaching and migration of fertilizer products below the root zone; and Using fertilizers that contain nitrification inhibitors, which reduce the rate of conversion of ammonia in fertilizers to nitrate. Although a range of techniques is available for the control of specific nitrate problems, their long-term effectiveness is difficult to predict. Control measures that limit or reduce nitrate in one part of the nitrogen cycle may increase it in another; for example, treatment processes that remove nitrate from waste waters also have the potential for increasing the release of ammonia or nitrous oxide to the atmos- phere. Commonly, the scientific data are inadequate for defining accurate relations among specific nitrate sources, best manage- ment or treatment practices, and their associat- ed environmental or economic impacts. Many of the source-control techniques for nitrate- related problems, especially for agriculture lands, are cost- or labor-intensive. Moreover, agricultural practices today require large inputs of energy and capital with relatively low re- turns. Given these scientific and economic con- straints, the reduction of nitrate concentrations in ground waters under intensively irrigated and fertilized croplands to levels compatible with drinking-water criterion may be difficult to achieve. Additional research is needed before an accurate determination can be made of the ultimate health risks involved on a national scale or the most feasible methods of control- ling nitrate contamination of ground water. Important areas of research related to water- quality impacts of human manipulation of the nitrogen cycle have been summarized in consid- erable detail by the National Research Council (1978, p. 721) and by Schaller and Bailey (1983, p. 455). Research needs relative to ground-water nitrate problems include: Site-specific (as opposed to State or regional) informa- tion on crop-yield response to nitrogen fertilizers under varying management conditions and weather patterns; More precise data on actual rates of nitrogen fertilizer consumption at the watershed level; Additional studies of the fate of nitrogenous compounds in soils based on actual field conditions; More precise information on the effectiveness and the economic and social impact of various best manage- ment practices to control potential nitrate pollution; Better information on the long-term influences of chang- ing land use patterns on the transport of nitrogen into subsurface and ground waters; Improved models of the rate of movement, fate, and storage of nitrogen in managed ecosystems on local and regional scales; Further evaluation of the health hazards posed by nitrate in water; and Design of alternative, regionally specific control strate- gies. SELECTED REFERENCES Boyce, J. S., Muir, John, Edwards, A. P., Seim, E. C., and Olson R. A., 1976, Geologic nitro- gen in Pleistocene loess of Nebraska: Journal of Environmental Quality, v. 5, no. 1, p. 93-96. Federal Water Quality Administration, 1969, Col- lected papers regarding nitrates in agricultural waste waters: Federal Water Quality Adminis- tration Water Pollution Control Research Series 13030 ELY 12/69, 186 p. Feth, J. H., 1966, Nitrogen compounds in natural water A review: Water Resources Research, v. 2, no. 1, p. 41-58. Freeze, R. A., and Cherry, J. A., 1979, Ground water: Englewood Cliffs, N.J., Prentice-Hall, p.413-416, 442-444. Fuhriman, D. K., and Barton, J. R., 1971, Ground water pollution in Arizona, California, Nevada, and Utah: U.S. Environmental Protection Agency Water Pollution Control Research Series 16060ERU 12/71,249 p. Gormly, J. R., and Spalding, R. F., 1979, Sources and concentrations of nitrate-nitrogen in ground water of the Central Platte Region, Nebraska: Ground Water, v. 17, no. 3, p. 291-301. Hendry, M. J., McCready, R. G. L., and Gould, W. D., 1984, Distribution, source and evolu- tion of nitrate in a glacial till of southern Alber- ta, Canada: Journal of Hydrology, v. 70, p. 177-198. Hull, L. C., Bertoldi, G. L., and Fogelman, R. P., 1985, Nitrate in ground water Sacramento Valley, California: Ground Water. [In press.] Katz, B. H., Lindner, J. B., and Ragone, S. E., 1980, A comparison of nitrogen in shallow ground water from sewered and unsewered areas, Nassau County, New York, from 1952 through 1976: Ground Water, v. 18, no. 6, p. 607-616. Keller, W. D., and Smith, G. E., 1967, Ground- water contamination by dissolved nitrate: Geo- logical Society of America Special Paper No. 90,59 p. Kreitler, C. W., and Jones, D. C., 1975, Natural soil nitrate The cause of the nitrate contamination of ground water in Runnels County, Texas: Ground Water, v. 13, no. 1, p. 53-61. Kreitler, C. W., Ragone, S. E., and Katz, B. G., 1978, N 15/N 14 ratios of ground-water nitrate, Long Island, New York: Ground Water, v. 16, no. 6, p. 404-409. Liebhardt, W. C., 1972, Manure and the nitrate problem, in Lime and Fertilizer Conference: Delaware-Maryland Plant Food Association Proceedings, 2 p. McDonald, D. B., and Splinter, R. C., 1982, Long- term trends in nitrate concentration in Iowa water supplies: Journal of American Water Works Association, v. 74, no. 8, p. 437-440. Miller, D. W., ed., 1980, Waste disposal effects on ground water: Berkeley, Calif., Premier Press, 512p. Miller, D. W., Deluca, F. A., and Tessier, T. L., 1974, Ground water contamination in the north- east States: Washington, D.C., U.S. Environ- National Water Summary 1984 Water-Quality Issues 105 mental Protection Agency, Office of Research and Development, 328 p. Miller, M. R., and Bergantino, R. N., 1983, Distri- bution of saline seeps in Montana: Montana Bureau of Mines and Geology Hydrogeologic Map 7, 7 p. Mink, L. L., Gilmour, C. M., Beck, S. M., Milligan, J. H., and Braun, R. L., 1976, The selection and management of feedlot sites and land dis- posal of animal waste in Boise Valley, Idaho: Ground Water, v. 14, no. 6, p. 411-425. National Research Council, 1972, Accumulation of nitrate: Washington, D.C., National Academy Press, 106 p. __1978, Nitrates An environmental assessment: Washington, D.C., National Academy Press, 723 p. Naymik, T. G., and Barcelona, M. J., 1981, Charac- terization of a contaminant plume in ground water, Meredosia, Illinois: Ground Water, v. 19, no. 5 p. 517-526. Perlmutter, N. M., and Koch, Ellis, 1972, Prelimi- nary hydrogeologic appraisal of nitrate in ground water and streams, southern Nassau County, Long Island, New York: U.S. Geologi- cal Survey Professional Paper 800-B, p. B225-B235. Porter, K. S., 1980, An evaluation of sources of nitrogen as causes of ground-water contamina- tion in Nassau County, Long Island: Ground Water, v. 18, no. 6, p. 617-625. Pye, V. L, Patrick, Ruth, and Quarles, John, 1983, Groundwater contamination in the United States: Philadelphia, University of Pennsyl- vania Press, 315 p. Ritter, W. F., and Chirnside, A. E. M., 1984, Impact of land use on ground-water quality in southern Delaware: Ground Water, v. 22, no. 1, p.38-47. Robertson, F. N., 1979, Evaluation of nitrate in the ground water in the Delaware Coastal Plain: Ground Water, v. 17, no. 4, p. 328-337. Saffigna, P. G., and Keeney, D. R., 1977, Nitrate and chloride in ground water under irrigated agriculture in central Wisconsin: Ground Wa- ter, v. 15, no. 2, p. 170-177. Schaller, F. W., and Bailey, G. W., eds., 1983, Agricultural management and water quality: Ames, University of Iowa Press, 472 p. Schultz, T. R., Randall, J. H., Wilson, L. G., and Davis, S. N., 1976, Tracing sewage effluent recharge Tucson, Arizona: Ground Water, v. 14, no. 6, p. 463-471. Silver, B. A., and Fielden, J. R., 1980, Distribution and probable source of nitrate in ground water, Paradise Valley, Arizona: Ground Water, v. 18, no. 3, p. 244-251. Smith, G. E., 1966, Many gremlins...not just one contribute to nitrate buildup: Fertilizer Solu- tions (May-June 1966). Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001,56 p. Spruill, T. B., 1982, Nitrate-nitrogen concentrations in ground water from three selected areas in Kansas: U.S. Geological Survey Water- Resources Investigations 82-11, 32 p. __1983, Relationship of nitrate concentrations to distance of well screen openings below casing water levels: Water Resources Bulletin, v. 19, no. 6, p. 977-981. Stewart, B. A., Viets, F. G., Jr., and Hutchinson, G. L., 1968, Agriculture's effect on nitrate pollution of ground water: Journal of Soil and Water Conservation, v. 23, p. 13-15. Thomas, G. W., 1970, Soil and climatic factors which affect nutrient mobility, in Engelstad, O. P., ed., Nutrient mobility in soils Ac- cumulation and losses: Madison, Wis., Soil Science Society of America, p. 1-20. U.S. Bureau of the Census, 1982, Statistical ab- stracts of the United States, 1982-83: Washing- ton, D.C., U.S. Government Printing Office, 1008 p. U.S. Environmental Protection Agency, 1982, Max- imum contaminant levels (subpart B of part 141, National interim primary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, parts 100 to 149, revised as of July 1, 1982, p.315-318. Viets, F. G., Jr., and Hageman, R. H., 1971, Fac- tors affecting the accumulation of nitrate in soil, water, and plants: U.S. Agricultural Re- search Service Agriculture Handbook No. 413, 62 p. Walton, G., 1951, Survey of literature relating to infant methemoglobinemia due to nitrate- contaminated water: American Journal of Pub- lic Health, v. 41, p. 986-996. 106 National Water Summary 1984 Hydrologic Perspectives Water-Availability Issues GROUND-WATER-LEVEL CHANGES IN FIVE AREAS OF THE UNITED STATES By LarryJ. Mann An assessment of State water issues in the 1983 National Water Summary (U.S. Geologi- cal Survey, 1984) revealed that ground-water availability is a significant issue in almost every State. The development of the ground-water resources has led to declining ground-water levels in a number of areas of the country. Such declines may lead to streamflow deple- tion, land subsidence, saltwater intrusion, and increased pumping costs for water producers. Under natural conditions, ground water moves from areas of recharge to areas of dis- charge. The water may be discharged to springs or streams, lost to the atmosphere by evapo- transpiration, or directly discharged to the ocean in coastal areas. Generally, an equilibri- um prevails in which the long-term recharge of the ground-water system is balanced by the long-term discharge from it. Ground-water levels in an aquifer fluctuate in response to changes in the rate of recharge and discharge. When recharge exceeds dis- charge, water accumulates in storage and water levels rise. When discharge exceeds recharge, water is released from storage, and water levels fall. The intergranular pores, fractures, or solution openings in an unconfined aquifer are saturated with water below a free surface, termed the water table. The water table rises or falls as the volume of water in storage changes. In a confined or artesian aquifer, water com- pletely fills the pores, fractures, and solution openings within the aquifer and is confined under pressure by an overlying confined bed of low hydraulic conductivity. Changes in storage occur through elastic expansion and contrac- tion of the porous material and of the water in response to changes in pressure and, in some instances, through the inelastic compaction of fine-grained sediments with associated subsid- ence of the land surface. The water level in an artesian well stands above the top of the aquifer and, in some instances, may stand above the land surface, so that the well will flow if left open. For equal changes in water level, the changes in the volume of water stored in con- fined aquifers are much smaller than those in unconfined aquifers. Confining beds vary in their ability to retard water movement, and virtually all are capable of transmitting flow in response to a sufficient difference in water level. Those which transmit measurable flows are often termed semiconfining, or leaky confining, beds, and the associated water-bearing units are termed semiconfined aquifers. Their behavior generally falls between that described above for confined and unconfined aquifers. Under natural conditions, the largest fluc- tuations in ground-water levels for unconfined aquifers are seasonal. Short-term fluctuations in confined aquifers commonly occur due to such factors as changes in barometric pressure. In aquifers where long-term recharge balances discharge, including well withdrawals, ground- water levels may fluctuate from a few feet to a few tens of feet from one season of high levels to the next. However, in ground-water aquifers where large withdrawals from wells have caused discharge to exceed recharge over long periods of time, net declines may amount to tens or even hundreds of feet. These year-to-year de- clines may stop or even be reversed if pumpage is reduced, so that discharge is equal to or less than recharge. In the State-by-State summaries of ground-water resources, which occur later in this report, information on ground-water with- drawals also is included, and water-level de- clines in principal aquifers are discussed for some States. A number of areas of the United States exist, however, where ground-water level declines have been substantial (40 feet or more) in at least one aquifer since development began (fig. 58). The historical behavior of water levels in aquifers in five important areas of ground- water use in which such declines have occurred are described below. These areas, which are in California, Illinois, Louisiana, Virginia, and South Dakota, illustrate the range of hydro- logic conditions and water-use practices that cause changes in water levels in several regions of the country and identify some related ef- fects, such as land subsidence, that may cause problems for ground-water users. Another related effect is the increased cost of ground- National Water Summary 1984 Water-Availability Issues 107 Figure 58. Areas of the con- terminous United States where water-table decline or artesian water-level decline in excess of 40 feet in at least one aquifer has occurred since develop- ment began. Areas describ- ed in the text are San Joa- quin Valley, Calif. (A), Chi- cago, ML, area (B), Baton Rouge, La. (C), Franklin, Va., area (D), and the Dako- ta aquifer of South Dakota (E). (Source: U.S. Geological Survey, 1984, p. 40.) water withdrawals as as result of increased energy prices and changes in water levels. A case study of this effect in Floyd County, Tex., completes the "Water-Availability Issues" sec- tion. SAN JOAQUIN VALLEY, CALIFORNIA The San Joaquin Valley (fig. 58) occupies the southern two-thirds of the Central Valley of California. It is a broad structural trough bounded by mountains in the west, east, and south and by the Sacramento-San Joaquin River Delta on the north. The valley is about 250 miles (mi) long and 25 to 55 mi wide and is underlain by unconsolidated sediments derived from erosion of the surrounding mountains. These sediments form a large alluvial basin aquifer. The climate in the San Joaquin Valley is characterized by hot, dry summers and moder- ate, wet winters. The mean annual precipita- tion ranges from about 5 to 16 inches. The climate allows for a long growing season during which two or three crops commonly are har- vested in some areas. Due to the favorable climate, fertile soils, and the availability of water for irrigation, the San Joaquin Valley has developed into one of the more productive agricultural areas in the world. Significant development of ground-water resources to satisfy the need for irrigation water began in the early 1900's. As ground-water withdrawals increased to the point that dis- charge from the ground-water system exceeded recharge, perennial decline of water levels in the aquifer began. Water levels near Mendota, Calif., declined about 260 feet (ft) between 1940 and 1963 (fig. 59). The extraction of water in this part of the Central Valley resulted in the compaction of fine-grained sediments, which, in turn, caused subsidence of the land surface. During the period from 1940 to 1977, the area near Mendota subsided 29 ft (Ireland and others, 1984). By 1977, land subsidence in this area had ceased for the most part. In response to the problem of declining water levels, rising pumping costs, and land subsidence, the Federal Central Valley Project and the California State Water Project devel- oped a series of canals to bring surface water from northern California to the San Joaquin Valley. The Delta-Mendota Canal and the California aqueduct, major components of the two projects, began delivering water to the western part of the San Joaquin Valley, includ- ing the Mendota area, in the late 1960's. In 1968, when ground-water withdrawals were replaced by the surface water delivered by the aqueduct, the water level in the aquifer began to rise (fig. 59), although some land subsidence continued as a result of earlier withdrawals. By 1976, water levels had recovered about 200 ft, only to decline again in 1977 when California was struck by a 2-year drought. Old wells were reactivated, and new wells were drilled to meet the irrigation needs that the aqueduct could not provide. During this period of renewed pump- age, little or no renewal of compaction oc- curred. Thus, water was supplied largely from elastic storage release, rather than from com- 108 National Water Summary 1984 Hydrologic Perspectives 325 350 375 400 425 450 475 500 525 550 575 600 Alluvial basin aquifer (confined) Well 14/14-30E1 vl Well 14/14-30E2 N Estimated 1935 1940 1945 1950 1955 1960 1965 1970 1975 1980 1984 Figure 59. Water levels in three observation wells in an alluvial basin aquifer near Mendota, Calif., 1935 to 1983. (Source: Compiled by R. P. Fogelman from U.S. Geological Survey data.) paction; as a result, water levels declined rapid- ly, falling nearly 100 ft during the drought. By the end of 1978, however, pumpage had de- creased, and a rapid rise of water level had begun. Since the importation of surface water began, the total rise of water level has been nearly 240 ft in the western part of the San Joaquin Valley. Ground-water withdrawals calculated for the period from 1961 to 1977 for the Mendota area, which is about 100 square miles (mi2), show the dramatic reduction in withdrawals beginning in 1968 when imported surface water became available. As explained above, the increase in withdrawals in 1977 occurred as a result of the drought and resultant decrease in imported surface water. The relation between withdrawals and water-level decline and recov- ery can be seen by comparing the water with- drawals shown in the table below with the water levels shown in figure 59. Annual withdrawals in the Mendota area, San Joaquin Valley, Calif., 1961 to 1977 [Source: Diamond and Williamson, 1983] Year Withdrawals (billion gallons per year) 1961 ..-..--- 1962 -------- 1963 -------- 1964 -------- 1965 -------- 1966 -------- 1967 -------- 1968 -------- 1969 -------- 1970 -------- 1971 ..--.--- 1972 -------- 1973 -------- 1974 -------- 1975 -------- 1976 -------- 1977 -------- ----- 32.3 ----- 31.6 ----- 29.9 ----- 30.9 ----- 27.4 ----- 31.0 ----- 29.3 ----- 9.7 ----- 9.8 ----- 7.6 ----- 6.2 ----- 4.0 ----- 4.4 ----- 3.7 ----- 3.1 ----- 3.1 ----- 17.3 In the past few years, water levels have stabilized in the San Joaquin Valley and in some areas have risen, reflecting both the re- placement of pumpage by surface water and the effects of above-average precipitation during the winters of 1981-82 and 1982-83. CHICAGO, ILLINOIS, AREA In the Chicago, 111., area (fig. 58), two aquifers supply most ground water a deep sandstone aquifer, the Cambrian-Ordovician aquifer, in which ground water occurs under confined conditions, and a shallow dolomite aquifer in which conditions trend from uncon- fined to semiconfined with increasing depth. Water from both aquifers is used mainly for municipal supplies. From 1864 to 1980, the six-county area of metropolitan Chicago had experienced water- level declines of more than 850 ft in the sand- stone aquifer (Sasman and others, 1981). Ground-water levels in a well at Elmhurst, 111., are characteristic of water-level trends in the deep sandstone aquifer (fig. 60). From 1953 to 1980, the water level declined about 370 ft in response to an increase in the annual with- drawal; for example, from 1959 to 1980, with- drawals increased from 10.7 million gallons per day (Mgal/d) to 20.6 Mgal/d. Ground-water levels in a well at Itasca, 111., are representative of water-level trends in the shallow dolomite aquifer (fig. 60). Water levels declined about 50 ft from 1958 to 1978. The dolomite aquifer, like the deep sandstone aqui- fer, has been intensively used for municipal water supply. From 1960 to 1979, the with- drawals increased from 0.40 to 5.3 Mgal/d. The water-level decline in the shallow aquifer, although much smaller than the decline in the deeper aquifer, has reduced the saturated thick- ness of the dolomite aquifer by 57 percent at Figure 60. Water levels in observation wells in the sandstone aquifer at Elmhurst, III., and the dolo- mite aquifer at Itasca, III., 1953 to 1980. (Source: Compiled by M. G. Sherrill from U.S. Geological Survey data.) 0 100 200 300 400 500 600 700 800 1953 1955 Dolomite aquifer ,tasca we,, (semi-confined) Sandstone aquifer (confined) 1960 1965 1970 1975 1980 National Water Summary 1984 Water-Availability Issues 109 Itasca, and the percentage may be much greater in more heavily pumped areas. The amount of water-level decline in the semiconfined dolomite aquifer is much smaller per unit volume of water pumped than in the confined sandstone aquifer. For example, a 4.9-Mgal/d increase in withdrawals from the dolomite aquifer between 1960 and 1979 result- ed in about 50 ft of water-level decline; how- ever, an increase of nearly 10 Mgal/d from the sandstone aquifer between 1959 and 1980 resulted in about 250 ft of decline. Although the withdrawal from the sandstone aquifer was double that from the dolomite aquifer, the water-level decline was five times greater in the sandstone aquifer. The difference in the re- sponse of the two aquifers to a unit withdrawal of water reflects differences in storage proper- ties, in water-transmitting properties, and in the influence of hydrologic boundaries. No major land subsidence has been report- ed in the Chicago area as a result of the large ground-water withdrawals. This is because the rocks in the area are consolidated and resist compaction as water is withdrawn. The declining water level in the Elmhurst, 111., well that taps the sandstone aquifer is a source of concern to water users and managers in the Chicago area (Schicht and Moench, 1971). Artificial recharge of fresh water to the aquifer has been proposed as a solution, but reallocation of Lake Michigan water to replace part of the ground-water demand has been the principal management technique employed thus far. BATON ROUGE, LOUISIANA In the Baton Rouge, La., area (fig. 58), the "2,000-foot" sand is one of nine aquifers that occur at depths between about 400 and 2,800 ft below the land surface and is one of the princi- pal sources of freshwater for local industry. The aquifer, which is confined by overlying silt and clay, ranges in thickness from 150 to 300 ft and its top is about 2,000 ft below the land surface. It extends at least 30 mi to the east, north, and west of Baton Rouge and is bounded on the south by the Baton Rouge fault, which inhibits water movement and is the southern limit of freshwater in the aquifer. Before 1940, withdrawals from the "2,000-foot" sand gener- ally were less than 4 Mgal/d. By the early 1970's, however, withdrawals had increased to slightly more than 38 Mgal/d and, since 1974, have averaged about 37 Mgal/d. Before development, water levels in this confined aquifer were reported to be as much as 60 ft above the land surface, but, by the late 1940's, they were 30 feet below the land surface (fig. 61). In about 1950, water levels began declining at a rate of about 10 feet per year 2000-foot" sand (confined) 1950 1955 1960 1965 1970 1975 1980 1984 (ft/yr). Development accelerated about 1965, and water levels declined at a rate of 15 to 25 ft/yr until 1973. At that time a combination of events, which included a business recession and the implementation of Government regulations concerning treatment of industrial effluents, caused a sharp cutback in industrial pumping. This resulted in the beginning of a general recovery of water levels (fig. 61). Although public-supply pumping in the Baton Rouge area continued to increase slowly, water-level recov- ery occurred in the aquifer in the industrial district. About 1981, water demand was re- duced by industrial cutbacks resulting in addi- tional water-level rises. Today (1984), seasonal water-level fluctuations caused by pumping are 10 to 40 ft at pumping centers and 1 to 5 ft in outlying areas; otherwise, levels generally are stabilized or are rising gradually. Saltwater encroachment from the south in the "2,000-foot" sand as a result of the large EXPLANATION Fault-Dashed where inferred U, upthrown side D, downthrown side Saltwater front Water level in feet below (-) or above (+) mean sea level. Dashed where approximately located. Interval 20 feet Inferred direction of water movement Area where aquifer is thin or missing Proposed test drilling site Figure 61. Water levels in an observation well in the "2,000-foot" sand in Baton Rouge, La., 1943 to 1983. (Source: Compiled by George Cardwell from U.S. Geological Survey data.) Figure 62. Saltwater front, water-level contours, and location of fault in the "2,000-foot" sand as deter- mined during the 1965 test- drilling program in the Baton Rouge, La., area. (Source: Terry and others, 1979, p. N38.) 110 National Water Summary 1984 Hydrologic Perspectives Figure 63. Water levels in observation wells in the middle Potomac aquifer, 1943 to 1984. A, Franklin, Va. 6, Sebrell, Va. (Source: Compiled by J. F. Harsh from U.S. Geological Sur- vey data.) water-level declines is a major concern and has been monitored for about 20 years. Water-level differentials across the Baton Rouge fault zone near the industrial district pumping center are as much as 200 ft (fig. 62). The hydraulic conductivity of the fault zone is low, retarding the northward movement of saltwater (White- man, 1979; Torak and Whiteman, 1982); never- theless, a small amount of saltwater apparently has leaked through the fault zone and may be moving slowly northward toward the pumping center (Terry and others, 1979, p. N36). Land subsidence of about 1.3 ft has oc- curred locally in the Baton Rouge area as a result of pumpage from 1930 to 1940. Most of the early subsidence was attributed to decline in pressure in the shallower "400- and 600-foot" sands, but pressure declines in the deeper aqui- fers, especially the "2,000-foot" sand, are be- lieved to have been a significant factor in later 20 £ 40 3 C/3 i 60 80 m h- 100 LU LLJ £120 ^ 140 160 180 200 Middle Potomac aquifer (semi-confined) 1940 1945 1950 1955 1960 1965 1970 1975 1980 1984 2 ° cc w 20 Q 5 40 O [ll 60 £ 80 cc LLJ ^ 100 - 120 t S140 e Middle Potomac aquifer (semi-confined) 1940 1945 1950 1955 1960 1965 1970 1975 1980 1984 years. Instruments installed in 1975 to monitor compaction indicate that land subsidence has essentially halted coincidental with the rising water levels (Whiteman, 1980). FRANKLIN, VIRGINIA, AREA The most extensive and productive aquifers in the Virginia Coastal Plain are the lower, middle, and upper Potomac aquifers. The Potomac aquifers consist mainly of beds of sand locally separated by lenticular beds of silt and clay. The movement of water from one aquifer to another is impeded by the silt and clay beds, which locally confine the ground water in the beds of sand. The aquifers are part of a semiconfined, or leaky confined, multilay- ered aquifer system that extends from Long Island, N.Y., to South Carolina. The largest withdrawals of ground water from the lower and middle Potomac aquifers occur in the Franklin area of southeastern Virginia (fig. 58). Before the start of pumping, flowing wells were the source of water supply (Cederstrom, 1945). About 1940, water was beginning to be with- drawn from large-capacity industrial and mun- icipal wells in the Franklin area. Withdrawals increased steadily until 1967 (fig. 63), but, since then, generally have stabilized. Withdrawals at present are about 41 Mgal/d compared to about 5 Mgal/d in 1940. These withdrawals have caused water levels in the aquifers to decline over an area of more than 5,000 mi2 (Cosner, 1975). Hydrographs for observation wells show that the decline of water levels in the middle Potomac aquifer since the 1940's ranges from about 80 ft near the town of Sebrell to about 160 ft near Franklin (fig. 63). Water-level declines in the middle Potomac aquifer are about 30 ft in the vicinity of the Atlantic coast. Declines of this magnitude could cause saltwater to move inland in the aquifer, perhaps threatening freshwater sup- plies. However, computed flow velocities for water in the coastal area suggest the landward movement of salty water could not exceed a few feet per hundred years (P. P. Leahy, U.S. Geological Survey, oral commun., August 1983). In the lower and middle Potomac aquifers, water levels are not affected greatly by seasonal water-level changes in overlying aquifers be- cause of the low hydraulic conductivity of overlying and intervening confining beds. Data collected since 1979 show that aquifer compac- tion due to the decline of water levels is only a few hundredths of a foot at present (H. T. Hopkins, U.S. Geological Survey, written commun., August 1983). National Water Summary 1984 Water-Availability Issues 111 DAKOTA AQUIFER OF SOUTH DAKOTA The Dakota aquifer (fig. 58), also referred to as the Dakota-Newcastle aquifer, is made up of water-yielding sandstones of the Dakota Formation. The Dakota Formation ranges in thickness from more than 400 ft in east-central and southeastern South Dakota to less than 40 ft near the northern Black Hills and in the northwest-central part of the State (Hedges, 1968; Schoon, 1971; Howells, 1982). Water in the Dakota aquifer is confined except at the outcrop of the Dakota Formation near the Black Hills and possibly in the south- eastern part of South Dakota. In much of the eastern one-half of the State and before exten- sive development began, water levels in wells drilled into the aquifer rose above the land surface. According to available records, ground-water development began in 1881, prin- cipally for irrigation, water power, and munici- pal supplies (Nettleton, 1892; Darton, 1896). Development occurred because the wells provided large volumes of water, as much as 4,000 gallons per minute, and they did not have to be pumped; that is, the water flowed freely from the wells at the land surface. In some counties, township boards used tax money to drill two wells per township for irrigation. Where artesian pressure was adequate, wells were drilled to power flour mills, machine shops, and other industries. Many cities and towns tapped the Dakota aquifer to save both the cost of pumps and of pumping. By 1895, about 400 wells had been drilled, and the es- timated flow was 150 Mgal/d (Darton, 1896). In 1916, the State Engineer estimated that at least 10,000 wells had been drilled. In 1983, at least 10,000, and possibly more than 15,000, wells were in use or flowed unused. Estimated discharge from the Dakota aquifer through wells was 160 Mgal/d and may have ranged from 150 and 200 Mgal/d between 1895 and 1983 (Bradford, 1981). A generalized recon- struction of the approximate area in which wells flowed at the land surface in 1881 and, for contrast, the approximate area in which wells flowed at the land surface in 1983 are shown in figure 64. The pressures in flowing wells that tapped the aquifer declined rapidly after development began. An example of the pressure decline that occurred in the aquifer can be seen in the following data from a well near Woonsocket, Figure 64. Approximate area in South Dakota where wells in the Dakota aquifer flowed freely at the land surface before develop- ment (about 1881) and at the present time (1983). (Source: Compiled by L. W. Howells from U.S. Geologi- cal Survey data.) EXPLANATION Approximate area where the potentiometric surface of the Dakota aquifer was above land surface Before development (about 1881) Present day (1983) 112 National Water Summary 1984 Hydrologic Perspectives S. Dak., in the James River valley (L. W. Howells, U.S. Geological Survey, written commun., April 1984). Year Shut-in pressure (pounds per square inch) 1 888 i eon 1 8Q1 1915 ....... 1 O£1 - - - 250 - - - 155 - - - 130 - - - 45 - - - 23 Use of the well in which these pressures were recorded was discontinued in 1961. Pressures in other wells at Woonsocket have not de- creased significantly since that time (N. C. Koch, U.S. Geological Survey, oral commun., August 1984). The 227-pounds-per-square-inch reduction in the shut-in pressure between 1888 and 1961 is equivalent to about 520 ft of water-level de- cline; more than 90 percent of this decline occurred between 1888 and 1915. By 1910, almost all use of water from the Dakota aquifer for power had ceased. Irrigation use of the more saline ground water, which also is often high in sodium, resulted in both sodium and salt poisoning of soils after 4 to 6 years of irrigation. For this reason, much of the use of the water from the Dakota aquifer for irriga- tion had ended by 1900. For several decades thereafter, the major uses of ground water from the Dakota aquifer were for livestock, domestic, and municipal water supplies. In general, water from the Dakota aquifer contains 100 to 5,000 milligrams per liter (mg/ L) of sodium, 600 to 1,300 mg/L of sulfate, and 1,200 to 2,500 mg/L of dissolved solids. In some areas, the water may have fluoride con- centrations of as much as 6 mg/L. In the northwestern part of South Dakota, however, the water contains 6,000 to 12,000 mg/L of dissolved solids, mainly sodium and chloride (U.S. Geological Survey and U.S. Bureau of Reclamation, 1975). These values are very high relative to most municipal supplies and to the National Interim Drinking-Water Regulations (U.S. Environmental Protection Agency, 1982a, b). Consequently, use of water from the Dakota aquifer has decreased since 1970, and rural and municipal water systems have been constructed or developed from other sources. SELECTED REFERENCES Bradford, W., 1981, Water levels in bedrock aqui- fers in South Dakota: U.S. Geological Survey 17th Annual Report, part 2, p. 603-694. Cederstrom, D. J, 1945, Geology and ground-water resources of the Coastal Plain in southeastern Virginia: Virginia Geological Survey Bulletin 63, 384 p. Cosner, O. J., 1975, A predictive computer model of the Lower Cretaceous aquifer, Franklin area, southeastern Virginia: U.S. Geological Survey Water-Resources Investigations 51-74, 62 p. Darton, N. H., 1896, Preliminary report on artesian waters of a portion of the Dakotas: U.S. Geo- logical Survey 17th Annual Report, part 2, p. 603-694. Diamond, Jonathan, and Williamson, A. K., 1983, A summary of ground-water pumpage in the San Joaquin Valley, California, 1961-77: U.S. Geological Survey Water-Resources Investiga- tions 83-4037, 70 p. Hedges, L. S., 1968, Water resources of Beadle County, South Dakota, Part 1, Geology: South Dakota Geological Survey Bulletin 18, 66 p. Howells, L. W., 1982, Geohydrology of the Stand- ing Rock Indian Reservation, North and South Dakota: U.S. Geological Survey Hydrologic Investigations Atlas HA-644. Ireland, R. H., Poland, J. F., and Riley, F. S., 1984, Land subsidence in the San Joaquin Valley, California, as of 1980: U.S. Geological Survey Professional Paper 437-1, 193 p. Nace, R. L., 1960, Water management, agriculture, and ground-water supplies: U.S. Geological Survey Circular 415, 12 p. Nettleton, E. S., 1892, Artesian and underflow investigations: U.S. 52d Congress, 1st session, Senate Executive Document 41, part 2, 116 p. Poland, J. F., and Evenson, R. E., 1966, Hy- drogeology and land subsidence, Great Central Valley, California, in Bailey, E. H., ed., Geolo- gy of northern California: California Division of Mines and Geology Bulletin 190, p. 239-247. Sasman, R. T., Schicht, R. J. and others, 1981, Verification of the potential yield and chemical quality of the shallow dolomite aquifer in Du- Page County, Illinois: Illinois State Water Sur- vey Circular 149, 46 p. Schicht, R. J., and Moench, A. F., 1971, Projected ground-water deficiencies in northeast Illinois, 1980-2020: Illinois State Water Survey Circular 101,22 p. Schoon, R. A., 1971, Geology and hydrology of the Dakota Formation in South Dakota: South Dakota Geological Survey Report of Investiga- tions 104,55 p. National Water Summary 1984 Water-Availability Issues 113 Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56p. Terry, J. E., Hosman, R. L., and Bryant, C. T., 1979, Summary appraisals of the Nation's ground-water resources Lower Mississipi region: U.S. Geological Survey Professional Paper813-N, 41 p. Torak, L. J., and Whiteman, C. D., Jr., 1982, Applications of digital modeling for evaluating the ground-water resources for the "2,000-foot" sand of the Baton Rouge area, Louisiana: Louisiana Department of Technical Report 27, p. 6. U.S. Environmental Protection Agency, 1982a, Maximum contaminant levels (subpart B of Part 141, National interim primary drinking- water regulations): U.S. Code of Federal Regu- lations, Title 40, parts 100 to 149, revised as of July 1, 1982, p. 315-318. __1982b, Secondary maximum contaminant levels (section 143.3 of part 143, National secondary drinking-water regulations): U.S. Code of Fed- eral Regulations, Title 40, parts 100 to 149, revised as of July 1, 1982, p. 374. U.S. Geological Survey, 1984, National water sum- mary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. U.S. Geological Survey and U.S. Bureau of Recla- mation, 1975, Mineral and water resources of South Dakota: U.S. 94th Congress, 1st session, Interior and Insular Affairs Committee print. Whiteman, C. D., Jr., 1979, Saltwater encroach- ment in the "600-foot" and "1,500-foot" sands of the Baton Rouge area, Louisiana, 1966-78, including a discussion of saltwater in other sands: Louisiana Department of Transportation and Development, Office of Public Works Water Resources Technical Report 19, 49 p. __1980, Measuring local subsidence with exten- someters in the Baton Rouge area, Louisiana, 1975-79: Louisiana Department of Transporta- tion and Development, Office of Public Works Water Resources Technical Report 20, 18 p. 114 National Water Summary 1984 Hydrologic Perspectives DECLINING GROUND-WATER LEVELS AND INCREASING PUMPING COSTS: FLOYD COUNTY, TEXAS-A CASE STUDY By John E. Schefter Figure 65. Water levels in a well in the High Plains aqui- fer, Floyd County, Tex., 1940 to 1984. (Source: Com- piled by E. D. Gutentag from U.S. Geological Sur- vey data.) 50 100 q 150 200 O 250 t- t LLJ O High Plains aquifer (unconfined) 1940 1950 1960 1970 1980 1984 Irrigated agriculture in Floyd County, Tex., provides an extreme example of the effect that declining water levels and increased energy prices may have on the cost of ground-water withdrawals. Floyd County, which is in the northern part of the State, is underlain by the High Plains aquifer. Although ground-water levels have declined throughout much of the High Plains aquifer, the declines in northern Texas, in general, have been greater than any- where else (Luckey and others, 1981). The aquifer, which consists mainly of sand and gravel, commonly yields from 100 to 500 gal- lons per minute (gal/min) of water to wells and is the main source of water for irrigation. Ground-water withdrawals from the aquifer for irrigation began in the early 1940's. In 1958, the annual irrigation withdrawal in Floyd County was 61.5 billion gallons (gal), and by 1969 it had increased to 103.5 billion gal. However, by 1979, withdrawals had decreased to 57.7 billion gal (Texas Department of Water Resources, 1981). Some of the causes of this sharp decrease in withdrawals are explained below. Between 1945 and 1984, the water level in an observation well in Floyd County decreased from 60 to 245 feet (ft) below the land surface (fig. 65), mainly in response to the withdrawal of water for irrigation. The saturated thickness of the aquifer at that well was reduced from about 300 ft in the early 1940's to about 100 ft in 1980, a decrease in saturated thickness of about 67 percent (Luckey and others, 1981). The observation well is representative of condi- tions in about 400 square miles of Floyd Coun- ty, where ground-water levels have declined 100 ft or more since development began. The cost per acre-foot of pumping water between 1952 and 1981 from the observation well using different assumptions (constant energy cost and constant pressure head) is shown in figure 66. This cost is only that for electrical energy to lift water from the well; it does not include other operating and capital costs. Changes in pumping costs are summa- rized in the table. In terms of nominal (unadjusted for inflation) dollars, the cost of pumping water to the surface increased 594 percent from 1952 to 1981. The change in the nominal cost is due to the following factors: changes in the depth to water and changes in the price of electrical energy. Had electricity remained at its 1952 price, the cost of pumping water would have increased only 172 percent due to declining water levels alone. However, electricity prices did not remain constant; they declined slightly between 1952 and 1973, and increased 233 percent between 1973 and 1981 (Stevens and Cumming, 1977; Sam Thomas, Southwest Pub- lic Service, oral commun., 1982). Had the water level remained at the 1952 level, the cost of pumping would have declined until 1973 and then increased in subsequent years for an aver- age increase of 155 percent due solely to in- creased energy prices from 1952 to 1981. Over the entire 30-year period (1952-81), declining water levels contributed more to in- creased pumping costs than did increased energy prices. However, between 1973 and 1981, increased energy prices contributed more to increased pumping costs than did declining water levels. In that period, pumping costs increased 302 percent. Had the water level remained constant at the 1973 level, pumping costs would have increased 233 percent due to the increase in energy price alone, and had the energy price remained at its 1973 level, pump- ing costs would have increased only 21 percent due solely to declining water levels. National Water Summary 1984 Water-Availability Issues 115 Although the cost of pumping water in- creased 594 percent between 1952 and 1981, the index of prices received by farmers for their crops increased 116 percent over the same peri- od. It cost about $3.82 to lift 1 acre-foot of water to the surface in 1952 and about $26.47 in 1981. But, in 1952 the index of prices received by farmers for their crops stood at 62 (1977 = 100), whereas it was equal to 134 in 1982 (Council of Economic Advisors, 1983). Thus, pumping cost, relative to the crop price index, increased 221 percent over the 30-year period. The decrease in annual ground-water with- drawals, from 103.5 billion gal in 1969 to 57.7 billion gal in 1979 can be attributed partially to increased pumping costs, declining well yields, and resulting changes in irrigation practices. Between 1969 and 1979, 22,000 acres were taken out of irrigation, a decline of about 7 percent. During this same period, the volume of irrigation water applied decreased from 1.0 acre-foot per acre (acre-ft/acre) in 1969 to 0.6 acre-ft/acre in 1979. Total irrigated acreage in the southern High Plains of Texas, which in- cludes Floyd County, dropped 10 percent dur- ing that period and the average rate of applica- tion of water dropped 15 percent, from 1.2 to 1.0 acre-ft/acre (Texas Department of Water Resources, 1981). These changes undoubtedly are related to pumping costs, but changes in other production costs also played a role, as have changes in the prices received by farmers for their crops (Sloggett and Mapp, 1984). Figure 66. Estimated pump- ing costs at an observation well in Floyd County, Tex., 1952 to 1981, based on four scenarios: A, observed (his- toric) changes in water levels and energy prices; B, changes in energy prices with constant water levels; C, changes in water levels with constant energy prices; and D, relative to in- dex of crop prices received by farmers. (Source: Com- piled by J. E. Schefter.) 1950 1960 1970 1980 Percentage changes in pumping costs due to changes in energy prices and ground-water levels, for three time periods [Percentages in rows do not add because base year used for calculation of first column (1952) differs from that used in second (1973)] Factors affecting changes in pumping costs Percentage change in pumping costs 1952 to 1973 1973 to 1981 1952 to 1981 Observed (historic changes in Changes attributable to water-level Changes attributable to energy price; - - 73 - - 125 -23 302 21 233 594 172 155 SELECTED REFERENCES Council of Economic Advisors, 1983, Economic report of the President, 1983: Washington, D.C., U.S. Government Printing Office, 343 p. Luckey, R. R., Gutentag, E. D., and Weeks, J. B., 1981, Water-level and saturated thickness changes, predevelopment to 1980, in the High Plains aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: U.S. Geological Survey Hydrologic Investigations Atlas HA- 652. Sloggett, G. R. and Mapp, H. P., 1984, An analysis of rising irrigation costs in the Great Plains: Water Resources Bulletin v. 20, no. 2, p. 229-233. Stevens, Maria, and Cumming, Ginny, 1977, Texas energy A twenty-five year history: Austin, Tex.: Forecasting and Policy Analysis Division, Governor's Energy Council, Report No. 77004, p. 89-91. Texas Department of Water Resources, 1981, Inven- tories of irrigation in Texas, 1958, 1964, 1969, 1974, 1979: Texas Department of Water Re- sources Report 263, 295 p. 116 National Water Summary 1984 Hydrologic Perspectives Aerial infrared view of center pivot irrigated field patterns near Imperial, Neb., September 1979. The dark-red fields are primarily irrigated corn; the center pivot in the northeastern part of the photograph is in fallow. (Photograph by U.S. Environmental Protection Agency for U.S. Geological Survey Regional Aquifer System Analysis study of the High Plains aquifer.) State Summaries of Ground-Water Resources 117 118 National Water Summary 1984 Ground-Water Resources INTRODUCTION TO STATE SUMMARIES OF GROUND-WATER RESOURCES By Ralph C. Heath The "State Summaries of Ground-Water Resources" part of the 1984 National Water Summary contains descriptions of the occurrence, use, and gener- al quality of the ground-water resources of each State, the District of Columbia (combined with Maryland), Puerto Rico, the U.S. Virgin Islands, and the Trust Territory of the Pacific Islands, Saipan, Guam, and American Samoa. (Hereafter, the term "State" is used for all geographic areas.) Each summary contains the following components: General setting Highlights of the physiographic, hydrologic, and geologic framework of the ground-water system. Principal aquifers A description of location, geology, and use of the aquifers. Ground-water withdrawals and water-level trends A description of the location and purpose of major ground-water withdrawals and the trends in water levels. Ground-water management A description of ground-water relat- ed laws and regulations and an identification of management agencies. Selected references A listing of relevant reports on ground-water resources. Table 1, Ground-water facts A tabulation of ground-water with- drawals for various uses in relation to total water withdrawals. (Not included with the Trust Territory of the Pacific Islands, Saipan, Guam, and American Samoa.) Table 2, Aquifer and well characteristics A listing of important characteristics of the principal aquifers and of the water-supply wells drilled in the aquifers. (Table 1 in Trust Territory of the Pacific Islands, Saipan, Guam, and American Samoa.) Figure 1, Principal aquifers A map showing geographic distribu- tion of the principal aquifers. Figure 2, Areal distribution of major ground-water withdrawals and trends in ground-water levels A map showing areas of withdrawals, hydrographs showing the long-term water level trends of aquifers, and a tabulation of areas of withdrawals and use of the water. In the State summaries, common ground-water terms are used, and reference is made, without explana- tion, to basic ground-water principles. Some of those terms and principles are described briefly in the glossary at the end of the report. Additional discussions of basic ground-water terms and principles and of the general features of ground-water occurrence in the United States are found in Heath (1983, 1984). IMPORTANCE OF GROUND WATER TO THE NATION Ground water is available in at least small amounts at nearly every point on the Earth's surface, making it one of the most widely available of all natural re- sources. It serves as the only, or the dominant, source of drinking water for most rural areas, as the largest source of water for irrigation and other purposes in arid and most semiarid regions, and as an important source of water for urban, industrial, and supplemental irriga- tion purposes in humid areas. The importance of ground water in the United States is shown graphically in figure 67. Nationwide, ground-water withdrawals in 1980 (excluding those for thermoelectric power) range from less than 1 percent of the total water withdrawal in the District of Columbia to 85 percent of that in Kansas. In 10 States, ground water represents more than one- half of the total withdrawal. By far the largest use of ground water is for irriga- tion. States with the largest ground-water use are those in the western part of the conterminous United States Arizona, California, Idaho, Kansas, Nebraska, and Texas where irrigated agriculture is a major ac- tivity. In the eastern part of the country, States that use large amounts of ground water for irrigation include Arkansas, Florida, Louisiana, and Mississippi. The importance of fresh ground water to the differ- ent States readily can be seen by comparing ground- water withdrawals to total fresh surface-and ground- water withdrawals (table 9). Total withdrawals, as given in water use reports, usually include thermoelec- tric power withdrawals mainly for condenser and reac- tor cooling and related purposes. Because water used for thermoelectric power must be available in very large quantities, 99 percent of it is obtained from surface- water sources, of which 30 percent is from saline sur- face-water bodies. Thus, the inclusion of thermoelec- tric power in total withdrawals tends to obscure the relative importance of ground and surface water for other uses, such as for public supplies, irrigation, and industrial usage (exclusive of thermoelectric power). For this reason, the ground-water facts table in each State summary shows total withdrawals including and excluding thermoelectric power. DELINEATION OF PRINCIPAL AQUIFERS IN THE STATE SUMMARIES In each State summary, the aquifers that are devel- oped most intensively for water supplies are identified, and their areal extents are shown on a map (fig. 1 in each summary). Areas in many of the States, and especially those that occupy parts of the Atlantic and Gulf Coastal Plains, are underlain by two or more aquifers separated by confining beds. In most in- stances, the maps show the uppermost of these multiple aquifers, although the maps for some States delineate the most-used aquifers. The relative vertical positions of the aquifers and of the intervening confining beds are indicated on cross sections or in block diagrams which show schematically the arrangement of the aquifers and confining beds along vertical slices through the Earth's National Water Summary Ground-Water Resources 119 PUERTO RICO AND U.S. VIRGIN ISLANDS Figure 67. Ground-water withdrawals in 1980 for the United States, Puerto Rico, and U.S. Virgin Islands. (Source: Modified from Solley and others, 1983.) crust. To help the reader visualize the aquifer distribu- tion in relation to land forms, figure 1 also has a small map showing the physiographic divisions of the State. The relative vertical positions of the aquifers in each State also are indicated in a table of aquifer and well characteristics (table 2 in each summary). Thus, it will be useful to refer to this table while scanning the aquifer map and the cross section or block diagram. In some areas, an aquifer occurring in the same geologic formation is identified by one name in one State and by another in an adjacent State. In preparing this report, attempts were made to resolve these differ- ences in names; however, several remain. Where appro- priate, the corresponding name(s) of the aquifer in the adjacent State is given in the table 2 "Remarks" column to aid in understanding aquifer nomenclature. The importance of an aquifer as a source of water may change from one State to another because of changes in demands for freshwater, variations in ground-water quality, and differences in the hydro- geologic characteristics of the aquifer. The differences may be of such magnitude that an aquifer that serves as a principal source of supply in one State may not be intensively developed in a neighboring State. For these reasons, the aquifer boundaries depicted in figure 1 of each State summary may not match at State boundaries. RESPONSE OF AQUIFERS TO WITHDRAWALS A map showing the location of major withdrawals and, through the use of symbols, the magnitude of the withdrawals, is given for each State (fig. 2 in each summary). Also included in this figure are hydrographs that show, in some cases, the effects of climatic changes and, in others, the long-term effect of withdrawals on ground-water levels; the hydrograph data are the annual greatest depth to water. A list of the withdrawal points, the name of the aquifer, and the principal uses of withdrawals also is provided. Changes in the position of the water level in wells reflect changes in the amount of ground water in storage in aquifers, and, where these changes are due to withdrawals, they also may reflect changes in flow direction. Thus, the measurement of the position of the water levels in wells is an important part of most ground-water investigative programs. These water-level measurements are most readily understandable in the form of hydrographs as given in the State summaries and in the form of water-level maps, which can be used to determine directions of flow. The hydrographs in- cluded in the State summaries were selected, in most instances, to show the effect of withdrawing ground water from the most intensively developed aquifers. 120 National Water Summary 1984 Ground-Water Resources Table 9. Summary of fresh ground-water withdrawals as a percentage of total fresh surface- and ground-water withdrawals for all categories of use and for specific categories of use, by State [Data rounded to two significant figures. Data not included for Trust Territory of the Pacific Islands, Saipan, Guam, and American Samoa. Mgal = million gallons. Sources: State data from table 1 in respective State summary, National Water Summary 1984; total data from Solley, Chase, and Mann, 1983] Total surface- and State ground-water withdrawals per day Alabama - - - Alaska - - - - Arizona - - - Arkansas - - - California - - Colorado - - - Connecticut- - Delaware - - - District of Columbia - Florida- - - - Georgia - - - Hawaii - - - - Idaho - - - - Illinois - - - - Indiana- - - - Iowa- - - - - Kansas - - - - Kentucky - - - Louisiana- - - Maine - - - - Maryland- - - Massachusetts - Michigan - - - Minnesota - - Mississippi - - Missouri - - - Montana - - - Nebraska - - - Nevada- - - - New Hampshire New Jersey - - New Mexico- - New York- - - North Carolina North Dakota - Ohio- - - - - Oklahoma - - Oregon- - - - Pennsylvania - Puerto Rico - - Rhode Island - South Carolina South Dakota - Tennessee- - - Texas - - - - Utah- - - - - U.S. Virgin Islands - - - Vermont - - - Virginia - - - Washington- - West Virginia - Wisconsin - - Wyoming - - - Total or percentage - (Mgal) 8,700 220 7,300 33,000 38,000 16,000 1,300 140 340 7,300 6,700 1,700 18,000 18,000 14,000 3,200 6,600 4,600 12,000 850 1,400 2,500 15,000 3,100 2,900 6,900 11,000 12,000 3,600 380 2,900 3,900 7,900 8,100 1,000 13,000 1,700 6,800 16,000 1,100 170 5,800 690 10,000 16,000 4,300 6 340 5,600 8,200 5,600 5,900 5,300 380,000 Percentage Ground- of water population served by ground water 52 69 65 50 46 15 32 60 0 90 48 95 88 49 32 82 49 31 69 57 30 33 43 75 93 34 54 82 50 60 45 89 35 55 62 42 41 61 44 26 24 42 77 51 47 63 42 54 41 71 53 70 54 51 withdrawals per day {Mgal) 290 49 4,200 4,300 14,600 2,800 150 82 .8 3,800 1,200 710 6,300 980 1,200 900 5,600 180 1,800 80 175 320 530 670 1,500 470 200 7,100 710 65 730 1,800 970 770 110 740 960 1,100 1,000 246 37 210 330 460 9,700 770 1.1 45 370 750 220 580 540 88,000 All categories of use1 3 22 58 13 39 18 11 59 52 18 41 35 5 11 28 85 4 14 9 13 13 4 22 54 7 2 59 20 17 25 47 12 10 11 6 56 17 6 22 22 4 48 5 61 18 18 13 7 9 4 10 10 23 (14) (26) (57) (81) (38) (18) (20) (57) .2 (.4) (69) (52) (37) (35) (24) (30) (81) (89) (22) (27) (10) (17) (28) (18) (48) (82) (34) (2) (73) (20) (21) (37) (47) (28) (20) (11) (32) (61) (17) (16) (35) (21) (21) (48) (21) (62) (18) (18) (50) (30) (9) (22) (46) (11) (38) Ground-water withdrawals as a percentage of total fresh surface- and ground-water withdrawals for Specific categories of use Public supply 28 43 54 42 46 8 17 38 0 86 29 90 94 27 41 81 48 13 44 19 9 24 17 52 18 22 39 77 40 48 40 90 23 12 54 27 28 29 16 22 15 22 68 40 46 66 12 35 17 37 27 48 33 35 Rural suDDlv Domestic 100 99 100 100 93 36 100 100 0 100 100 90 96 97 90 100 86 91 100 98 100 100 100 100 100 74 94 100 94 98 100 97 89 100 100 90 83 87 100 42 100 100 94 100 84 90 100 85 100 78 95 100 92 97 Livestock 34 0 82 36 41 18 18 100 0 66 61 96 42 100 18 100 43 5 70 59 54 58 77 85 77 26 38 80 31 25 67 50 65 85 40 60 12 27 88 50 50 55 88 17 49 80 0 62 10 67 13 96 21 55 Industrial self- supplied 1 0.6 (4) 9 72 1 54 2 3 68 27 8 73 95 1 8 13 35 2 5 5 6 6 1 5 21 2 20 3 30 5 10 25 4 6 2 23 15 4 3 36 1 54 2 23 14 0 2 2 15 3 1 34 6 (11) (88) (55) (89) (1) (10) (73) 6(57) (82) (57) (20) (95) (10) (18) (71) (77) (25) (12) (5) (18) (30) (3) (20) (61) (39) (52) (85) (45) (6) (20) (98) (11) (17) 3 (25) (16) (35) (16) (15) (21) (36) (5) (55) (11) (24) (16) (0) (35) (24) (15) (18) (15) (76) (26) Irrigation 30 0 58 86 39 19 8 63 0 53 66 93 25 100 98 84 92 6 47 3 54 28 37 88 35 75 1 67 17 0 73 44 46 30 37 36 84 14 14 34 9 27 33 51 70 10 0 19 29 4 8 97 8 40 Number in parentheses was calculated excluding thermoelectric power. National Water Summary 1984 Ground-Water Resources 121 These hydrographs represent only a small sample of those available from the U.S. Geological Survey and State ground-water agencies. The response of water levels in aquifers to ground-water withdrawals is de- scribed in detail in the 1983 National Water Summary (U.S. Geological Survey, 1984, p. 36-45). Estimates of well yields for each aquifer are given in table 2 of each State summary. These yields are the amounts of water per minute that can be obtained when an effort is made to design and construct wells to obtain large supplies of water, such as are needed for agricul- tural, public supply, or industrial uses. For most aqui- fers, they do not represent the average yield of all wells, which may include many small-yield rural domestic wells. A range of yields reflects the effect of areal differences in aquifer thickness or composition. The yields listed in the "May exceed" column are obtainable where conditions are especially favorable; for example, where an aquifer has its greatest thickness or is most permeable. All yields represent the rates at which individual wells can be pumped continuously for long periods. They do not, however, include the possible influence of interference from nearby wells and do not indicate the "safe" or sustained yields of the aquifer. GROUND-WATER MANAGEMENT The Nation's freshwater needs are met by with- drawals from streams, lakes, reservoirs, and ground- water systems. Trends in water developments over the last 30 years show that the use of ground water for all purposes, exclusive of thermoelectric power, has been increasing at a faster rate than has the use of surface water for the same purposes. Several factors may cause this trend to continue or accelerate in the future. First, the most cost-effective surface reservoir sites already have been developed (U.S. Geological Survey, 1984, p. 33) and the sustained yields of existing reservoirs are decreasing due to sedimentation. Second, the cost of storage at the remaining reservoir sites is becoming increasingly expensive. And third, public opposition is increasing to reservoir construction because of potential environmental damages. Thus, the development of alternative ground-water supplies and the protection of ground-water quality are management issues of critical importance. Discussion of the quality of ground water is limited in this report to identifying the natural condition of the water in those instances where it influences the use of the water. For the most part, data are available to assess the common constituents that influence the qual- ity of the Nation's ground water. However, much less is known about ground-water constituents that occur naturally in trace concentrations and about the degree and extent of contamination by human activities. Investigations by Federal and State agencies, universi- ties, and other groups are underway to address these technical aspects of ground-water management. To ensure that the Nation's future water demands are met, it is important that an infrastructure exists within each State to utilize the technical information and manage the ground-water resources. To achieve these ends, many States have enacted ground-water laws and regulations and have established organizations to implement them. A description of these management initiatives constitutes the final section of each State summary. SELECTED REFERENCES Heath, R. C., 1983, Basic ground-water hydrology: U.S. Geological Survey Water-Supply Paper 2220, 84 p. __1984, Ground-water regions of the United States: U.S. Geological Survey Water-Supply Paper 2242, 78 p. Ireland, R. L., Poland, J. F., and Riley, F. S., 1984, Land subsidence in the San Joaquin Valley, California, as of 1980: U.S. Geological Survey Professional Paper 437-1, 93 p. MacKichan, K. A., 1951, Estimated water use in the United States, 1950: U.S. Geological Survey Circular 115, 13 p. __1957, Estimated water use in the United States, 1955: U.S. Geological Survey Circular 398, 18 p. MacKichan, K. A., and Kammerer, J. C., 1961, Estimated use of water in the United States, 1960: U.S. Geological Survey Circular 456, 26 p. Murray, C. R., 1968, Estimated use of water in the United States, 1965: U.S. Geological Survey Circular 556, 53 p. Murray, C. R., and Reeves, E. B., 1972, Estimated use of water in the United States in 1970: U.S. Geological Survey Circular 676, 37 p. __1977, Estimated use of water in the United States in 1975: U.S. Geological Survey Circular 765, 37 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Theis, C. V., 1940, The source of water derived from wells, essential factors controlling the response of an aquifer to development: Civil Engineering, v. 10, no. 5, p. 277-280. U.S. Geological Survey, 1984, National water summary 1983 Hydrologic events and issues: U.S. Geological Survey Water-Supply Paper 2250, 243 p. U.S. Water Resources Council Hydrology Committee, 1980, Essentials of ground-water hydrology pertinent to water- resources planning: U.S. Water Resources Council Hy- drology Committee Bulletin 16 (revised), 38 p. 122 National Water Summary 1984 Ground-Water Resources Ground water rises to form Blue Spring beneath a bluff of Eminence Dolomite near Owls Bend, Mo. (Photograph by J. H. Barks.) ALABAMA Ground-Water Resources National Water Summary Alabama 123 Table 1. Ground-water facts for Alabama [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Baker, 1983] Population served by ground water, 1982 Ground water is used by 52 percent of the population of Alabama, even though it constitutes only 14 percent of the total freshwater used in the State, excluding thermoelectric use (Baker, 1983; Solley and others, 1983). Ground water also is used extensively for irrigation, livestock, and industrial- commercial supplies. Ground-water withdrawals in 1982 to- taled 290 million gallons per day (Mgal/d); withdrawals for Pe^ageo^Talpopulation" I I I I I I I I I I I I I 52 various uses and related statistics are given in table 1. From public water-supply systems: Number (thousands) ---------------- 1,481 Percentage of total population ------------ 37 GENERAL SETTING From rural self-supplied systems: ... . / i i-i ~,nr -i Number (thousands) ---------------- 611 Alabama comprises an area of about 51,705 square miles Percentage of total population - ----------- 15 (mi ) and has a population of about 4.1 million (1982 projec- I - i tion, University of Alabama, Center for Business and Eco- _________Freshwater withdrawals, 1982________ nomic Research, 1983). The State contains parts of five Surface water and ground water, total (Mgal/d) ------ 8,700 physiographic divisions (fig. 1) the Coastal Plain, Pied- Ground water only (Mgal/d) -------------- 290 mont Valley and Ridge Appalachian Plateaus and Interior ^Sage of lolalexdudmg withdrawals for" " " " " Low Plateaus provinces (Fenneman, 1938). The Coastal Plain thermoelectric power --------------- 14 province is underlain predominantly by unconsolidated sedi- T~ : ments that dip gently toward the south and southwest. Under- lying the Piedmont province are complexly folded and faulted Public-supply withdrawals: metamorphic rocks and massive igneous rocks. The Valley Ground water (Mgal/d)- - -------------- 160 JT-., v . . . i , r ,j . . r i. . u Percentage of total ground water - ----------- 55 and Ridge province is underlain by folded and faulted carbon- Percentage of total public supply- ----------- 28 ate rocks, sandstone, and shale. The Appalachian Plateau Per capita (gal/d) ------------------ 108 consists of plateaus underlain by sandstone, shale, siltstone, Rural-supply withdrawals: and coal. The Interior Low Plateau is underlain by beds of Domestic: carbonate rocks, sandstone, and shale that dip generally Ground water (Mgal/d)- - ------------- 46 *u j TU j-cc i c » A t AC c Percentage of total ground water - ---------- 16 southward. The differing geologic features and land forms of Percentage of total rural domestic ---------- 100 Alabama cause significant differences in ground-water quality per capita (gal/d) ----------------- 75 and availability. Livestock: Recharge to the ground-water system in Alabama is Ground water (Mgal/d) - -------------- 30 derived from precipitation. Normal annual precipitation Percentage of total ground water - ---------- 10 c u*>in-u/"\-ik>r* /-i * * Percentage of total livestock - ------------ 34 ranges from about 49 inches (in.) in Montgomery County to industrial self-supplied withdrawals: about 66 in. in southern Baldwin County, according to Na- Ground water (Mgal/d)- --------------- 51 tional Weather Service records for 1951 to 1980. Most of the Percentage of total ground water - ----------- 18 precipitation runs off to streams or is returned to the atmos- Percentage of total industrial self-supplied: phere by evaporation and transpiration; however, a small part Including withdrawals for thermoelectric power - - - - 0.6 (about 3-6 in.) recharges the ground-water system and sup- !^^^^i^wds for ±emoelcctnc ^^ ' ' ' ' 4 plies base flow to streams. Ground water (Mgal/d)- --------------- 12 Percentage of total ground water ------------ 4 Percentage of total irrigation ------------- 30 PRINCIPAL AQUIFERS Principal aquifers in Alabama consist of a sequence of unconsolidated sediments that underlie the Coastal Plain and consolidated sediments, carbonate rocks, and igneous and The Citronelle-Miocene aquifer consists of sand beds in metamorphic rocks that underlie the other four physiographic the Citronelle Formation of Pliocene age and in the undif- provinces in the State. The aquifers, which are grouped into ferentiated Miocene Series (Copeland, 1968; Barksdale and the Coastal Plain aquifers and non-Coastal Plain aquifers, are Moore, 1976). This aquifer is used primarily in Baldwin, described below and in table 2; their areal distribution is Mobile, Washington, and Escambia Counties in southwestern shown in figure 1. Alabama; wells commonly yield as much as 500 gallons per minute (gal/min). Water quality is generally suitable for COASTAL PLAIN AQUIFERS municipal, industrial, and irrigation uses but may be acidic Many of the principal aquifers in Alabama are in the and corrosive locally. Coastal Plain, and consist of, from youngest to oldest, the The Floridan aquifer system consists of porous limestone Citronelle-Miocene aquifer, the Floridan aquifer, the Tertiary in formations of Oligocene age and in the Ocala Limestone sedimentary aquifer system, and the Cretaceous aquifer sys- (Copeland, 1968; Barksdale and Moore, 1976). Yields from tern. Relatively impermeable sediments (chalk and clay) are this system may exceed 700 gal/min per well in southeastern present between the aquifers. Alabama. 124 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Alabama [Gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Reports of the U.S. Geological Survey and Alabama State agencies] Aquifer name and description Well characteristics Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Coastal Plain aquifers: Citronelle-Miocene aquifer: Sand, sandy gravel, sandy clay, gravel, and sandstone. Unconfined to confined. Floridan aquifer: Limestone and sand. Unconfined to confined. Tertiary sedimentary aquifer system: Sand, sandy clay, gravelly sand, and limestone. Unconfined to confined. Cretaceous aquifer system: Sand, gravelly sand, sandy clay, sandy limestone, and calcareous clay. Unconfined to confined. Non-Coastal Plain aquifers: Paleozoic carbonate aquifer system: Limestone and dolomite. Unconfined to confined. Pennsylvanian sandstone aquifer: Sandstone, shale, siltstone, and coal. Unconfined to confined. Igneous-metamorphic aquifer: Schist, phyllite, and quartzite saprolite. Unconfined to confined. 100-500 75-400 200 - 1,200 200-1,500 75-500 75-200 75-300 200-500 700 Principal aquifer in southwest Alabama. Water may be acidic and corrosive locally. 100-500 700 Includes Oligocene Series (undifferentiated) and Ocala Lime- stone. Principal shallow aquifer in ex- treme southeast Alabama. 350 - 700 1,000 Principal aquifer system in south- central and southeast Alabama. Water-level declines of 100 ft in Dothan. 300 - 1,000 1,400 Principal aquifer system in northern and central parts of the Coastal Plain. Water may contain chloride in excess of 250 mg/L locally, especially near major rivers, downdip at depths greater than 2,500 ft, and in areas where no principal aquifers are present. 100 - 500 1,000 Includes carbonate formations of Mississippian through Cambrian age. Important source of ground water from wells and springs in Valley and Ridge and Interior Low Plateaus physiographic provinces. 1-10 100 Primarily Pottsville Formation. Water may contain iron in excess of 0.3 mg/L locally. 1-10 100 Generally unproductive aquifer. Water may contain iron in excess of 0.3 mg/L locally. The Tertiary sedimentary aquifer system consists of sand beds in the Lisbon, the Tallahatta, the Hatchetigbee, and the Nanafalia Formations and limestone and sand beds in the Clayton Formation; this aquifer system is used extensively across southern Alabama, and wells generally yield 350 to 700 gal/min. The Cretaceous aquifer system consists of sand beds in the Providence Sand and the Ripley and Eutaw Formations and Tuscaloosa Group (Carlston, 1944; Barksdale and Moore, 1976); this aquifer system is used in a large part of the Coastal Plain of Alabama (fig. 1). The Providence-Ripley aquifer yields as much as 700 gal/min. Wells in the Eutaw aquifer generally yield between 700 and 1,000 gal/min. Wells in the Tuscaloosa aquifer, the lowermost of the Cretaceous aquifer system in Alabama, yield between 700 and 1,400 gal/min. Water quality in both the Tertiary sedimentary and Creta- ceous aquifer systems generally is suitable for municipal, industrial, and irrigation uses. However, chloride concentra- tions, downdip from outcrops, exceed 250 milligrams per liter (mg/L) in many areas; chloride concentrations are also high at depths of less than 200 feet in west-central Alabama. The iron concentration may exceed 0.3 mg/L locally with no geograph- ic pattern evident. NON-COASTAL PLAIN AQUIFERS The principal non-Coastal Plain aquifer is the Paleozoic carbonate aquifer system in the central and northern parts of the State. Two additional aquifers, the Pennsylvanian sand- stone and the igneous-metamorphic, are significant, even though well yields are small, because they are the only aquifers available over a large part of northern and eastern Alabama. The Paleozoic carbonate aquifer system consists of cav- ernous limestone and dolomite that range in geologic age from Mississippian to Cambrian (Johnston, 1933; Barksdale and Moore, 1976). These aquifers are used in the Valley and Ridge province and in the Interior Low Plateaus province (primarily the Tennessee Valley). Although well yields differ greatly in carbonate terranes, wells in these aquifers generally yield 100 gal/min and may yield 1,000 gal/min or more in some areas. The Pennsylvanian sandstone aquifer consists of sand- stone of the Pottsville Formation. Water in this aquifer is present in joints, fractures, and bedding-plane partings (John- ston, 1933; Barksdale and Moore, 1976). Wells in the Potts- ville generally produce less than 10 gal/min but may yield more than 100 gal/min. Water quality generally is acceptable for domestic and municipal uses; however, the iron concentra- tion commonly exceeds 0.3 mg/L. I A' National Water Summary Alabama 125 ^^i^f^m y£* v* EXPLANATION COASTAL PLAIN AQUIFERS [__I Citronelle-Miocene I Floridan I Tertiary Cretaceous NON-COASTAL PLAIN AQUIFERS Pennsylvanian Sandstone Paleozoic carbonate I I Igneous-metamorphic A A' Trace of cross section -2000 Figure 1. Principal aquifers in Alabama. A Geographic distribution. B, Physiographic diagram and divisions. C, Generalized cross section (A-A 1). (See table 2 for a more detailed description of the aquifers. Sources: A, Johnston, 1933; Carlston, 1944. B, Fenneman, 1938; Raisz, 1954. C, Copeland, 1968; Barksdale and Moore, 1976.) 126 National Water Summary Ground-Water Resources The igneous-metamorphic aquifer consists of schist, phyl- lite, quartzite, marble, granitic rocks, and saprolite (inplace decomposed rock in the Piedmont). Ground water is present in fault zones, joints, and other fractures in the bedrock and pore spaces in the saprolite. Wells in the Piedmont generally yield from 1 to 10 gal/min, but yields can exceed 100 gal/min. Water having an iron concentration greater than 0.3 mg/L is a common local problem. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Most cities and towns in the Coastal Plain of Alabama depend solely on ground water for water supplies. Exceptions are Mobile, Tuscaloosa, and Phenix City, which have sur- face-water supplies, and Montgomery, which uses ground and surface water. Most rural public water-supply systems in the Coastal Plain use ground water, as do almost all self-supplied homes and farms. Non-Coastal Plain areas that use ground water extensively include Madison County, Anniston, and Jefferson County (locations 1, 3, 5, fig. 2). These metropoli- tan centers have surface-water supplies, but ground water constitutes a significant part of the total water used. The distribution of major ground-water withdrawals and trends of ground-water levels near selected pumping centers are shown in figure 2. The largest concentrations of ground- water pumpage are in Madison, Calhoun, Montgomery, Mo- bile, and Houston Counties (locations 1, 3, 7, 9, 11, fig. 2). Water levels generally decline in response to increased pumping and recover when pumping is reduced. The hydro- graph for the well in Hale County (location 14, fig. 2) shows that the water level has been declining since 1961, as does the hydrograph for the well in Dale County (location 16, fig. 2). These declines are typical of Coastal Plain aquifers where pumpage has steadily increased during the past 40 years. The hydrograph for the well in Montgomery County (location 15, fig. 2) shows a general decline from 1958 to 1966, recovery from 1966 to 1976, and a decline from 1976 to 1981. The city of Montgomery pumped extensively from the Tuscaloosa aquifer until a surface-water plant was built in 1966. In 1976, the demand for water became greater than the capacity of the surface-water plant, and Montgomery resumed pumping from the Tuscaloosa aquifer. The hydrograph for the well in the Citronelle-Miocene aquifer in southern Baldwin County (lo- cation 17, fig. 2) shows an initial decline due to pumping, but it soon stabilizes and shows only seasonal fluctuations because pumping rates have not dramatically increased in the area. The hydrograph for the well in Madison County (location 13, fig. 2), which is used to monitor a Paleozoic carbonate aquifer, shows seasonal declines and recoveries; no long-term decline has occurred. This aquifer is recharged locally from precipitation and by the Tennessee River, and pumpage is small in relation to the amount of available recharge. Also, the observation well is not near any large pumping wells. In summary, trends in water levels are not consistent throughout the State. Long-term water-level declines in the Coastal Plain aquifers of Alabama are common where pump- age has increased during the past 40 years. Significant declines are not common in the non-Coastal Plain Paleozoic carbonate aquifers. GROUND-WATER MANAGEMENT Alabama has very little legislation pertaining to ground- water management. The Public Water Supply Section of the Water Division of the Alabama Department of Environmental Management (ADEM) regulates public-water supplies. Their regulation, however, mainly concerns the potability of the water and the adequacy of a water-supply system to meet demands. The ADEM certifies well drillers and develops well standards but generally does not participate in the selection of well sites or regulate the spacing of wells. Permits are required by the ADEM for any well within the Coastal Area Zone that produces 50 gal/min or more. The ADEM investigates reports of ground-water contamination and has the authority to close wells that produce water that is hazardous for human con- sumption. Self-supplied industrial, commercial, irrigation, and other agricultural users of ground water are not regulated in Alabama. The Geological Survey of Alabama and the ADEM, in cooperation with the U.S. Geological Survey, maintain a statewide water-data network and conduct investigations of Alabama's water resources. The research, data collection, and analyses provided by this cooperative program form an information base upon which ground-water management deci- sions can be made. National Water Summary Alabama 127 s e 5 12 fc 28 J 32 HH 36 5" - 13 Paleozoic carbonate aquifer Unconfined Missing record 1935 1945 1955 1975 1985 14 Cretaceous aquifer Confined 1935 1955 1965 1985 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) O 3.0-5 5.1-10 A Greater than 10 Location number 80 84 88 92 96 104 108 - IS Cretaceous aquifer Confined 1 1 1 1 1 1 1 1 1 120 140 160 180 200 220 240 260 280 300 16 Tertiary and Cretaceous ....... aquifers Confined 1935 1945 195S 1965 1975 1985 1935 Missing I I I I I I I I I 1945 1955 1965 1975 1985 O Withdrawal site 13 o Hydrograph only ^ 1 4 g 8 3 12 3 16 g ao 1 24 «c 28 1 32 ~ 17 Citronelle-Miocene Confined aquifer - Missing record l\ ^/rXV / ^\j v/v/w N/ _ I I i i i i i i i 1935 1955 1965 1975 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 Geographic area Washington County. . Houston County . . . Aquifer Paleozoic carbonate. . . ... .do .......... ... .do .......... ... .do .......... ... .do .......... ... .do .......... Citronelle-Miocene . . . ... .do .......... ... .do .......... Tertiery, Cretaceous . . Principal uses Public supply. Industrial. Public supply. Do. Do. Industrial. Do. Agriculture. Public supply. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected weils in Alabama. (Sources: Withdrawal data from Baker, 1983; water-level data from U.S. Geological Survey files.) 128 National Water Summary Ground-Water Resources SELECTED REFERENCES Adams, G. I., Butts, Charles, Stephenson, L. W., and Cooke, C. W., 1926, Geology of Alabama: Geological Survey of Alabama Special Report 14, 312 p. Baker, Jack, 1957, Geology and ground water of the Piedmont area of Alabama: Geological Survey of Alabama Special Report 23, 99 p. Baker, R. M., 1983, Use of water in Alabama, 1982: Geological Survey of Alabama Information Series 59C, 49 p. Barksdale, H. C., and Moore, J. D., eds, 1976, Water content and potential yield of significant aquifers in Alabama: Geological Survey of Alabama Open-File Report, 477 p. Carlston, C. W., 1944, Ground-water resources of the Cretaceous area of Alabama: Geological Survey of Alabama Special Report 18, 203 p. Copeland, C. W., 1968, Geology of the Alabama Coastal Plain: Geological Survey of Alabama Circular 47, 97 p. Davis, M. E., 1980, Ground-water levels in Alabama: Geological Survey of Alabama Circular 105, 74 p. Ellard, J. S., 1979, Map of fresh and slightly saline ground-water resources in the Coastal Plain of Alabama: Geological Survey of Alabama Special Map 179. Fenneman, N. M., 1938, Physiography of Eastern United States: New York, McGraw-Hill Book Co., 714 p. Gardner, R. A., 1981, Model of the ground-water flow system of the Gordo and Eutaw aquifers in west-central Alabama: Geological Survey of Alabama Bulletin 118, 30 p. Johnston, W. D., Jr., 1933, Ground water in the Paleozoic rock of northern Alabama: Geological Survey of Alabama Special Report 16, 414 p. Knowles, D. B., Reade, H. L., Jr., and Scott, J. C., 1963, Geology and ground-water resources of Montgomery County, Alabama, with special reference to the Montgomery area: U.S. Geological Survey Water-Supply Paper 1606, 76 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C.,U.S. Geological Survey, 417 p. Scott, J. C., Law, L. R., and Cobb, R. H., 1984, Hydrology of the Tertiary-Cretaceous aquifer system in the vicinity of Fort Rucker Aviation Center, Alabama: U.S. Geological Survey Water- Resources Investigations Report 84-4118, 221 p. Solley, W. B., Chase, E. B., Mann, W. B. IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Swindel, G. W., Jr., Williams, M. R., and Geurin, J. W. (revised by Baldwin, H. L.), 1963, Water in Alabama: U.S. Geological Survey Water-Supply Paper 1765, 89 p. University of Alabama, Center for Business and Economic Research, 1983, Annual population estimates by age, race, and sex for Alabama counties, 1980-1990: Tuscaloosa, Ala., University of Alabama Press, 143 p. Prepared by John C. Scott, John S. Williams, and Ann K. Sparkes For further information contact District Chief, U.S. Geological Survey, 520 19th Avenue, Tuscaloosa, AL 35401 U.S. Geological Survey Water-Supply Paper 2275 ALASKA Ground-Water Resources National Water Summary Alaska 129 Table 1. Ground-water facts for Alaska [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983]______________________________ Population served by ground water, 1980 Alaska has abundant surface-water resources, but many of the streams and lakes are frozen for most of the year and most of the larger streams transport glacial silt that makes the water unacceptable for many uses. These factors lend special significance to ground water as a source of supply, even though permafrost (perennially frozen ground) profoundly affects the occurrence and availability of ground water in all Number (thousands) - ------------------ 276 , . ., ., , /M7-11- in c- i\ r» Percentage of total population -------------- 69 but the south coastal regions (Williams, 1970; fig. 1). Perma- From puglic water.su^,ly systerns: frost forms a virtually impermeable layer that restricts re- Number (thousands) ----------------- 172 charge, discharge, and movement of ground water, functions Percentage of total population- ------------ 43 as a confining layer, and decreases the volume of uncon- rmH^vSSSS^^K- ------------- ,04 solidated deposits and bedrock in which water may be stored Percentage of total population- ------------ 26 (Zenone and Anderson, 1978, p. 1). Freshwater withdrawals, 1980 Ground water constitutes 22 percent of total water use in c ,. . , , t t . i/», ,,^\ -> K Surface water and ground water, total (Mgal/d) ------- 220 the State. Aquifers provide water to 276,000 people (69 Ground water only (Mgal/d) --------------- 49 percent of the population), of which 172,000 rely on public Percentage of total- ----------------- 22 water-supply systems and 104,000 on rural (private) systems. Percentage of total excluding withdrawals for . - i j i i- ,r\o« j i thermoelectric power ---------------- 26 Ground-water withdrawals for various uses in 1980 and relat- ed statistics are given in table 1. _____________Category of use_____________ Public-supply withdrawals: GENERAL SETTING Ground water (Mgal/d)- --------------- 23 Percentage of total ground water- ----------- 47 Major landforms or Alaska include three great mountain Percentage of total public supply- ----------- 43 ranges the Coastal, the Alaskan, and the Brooks from Per capita (gal/d) ------------------ 134 south to north; a broad interior lowland that is drained by Rural-supply withdrawals: large rivers and contains scattered highlands and plateaus; and Ground water (Mgal/d)- -------------- n large coastal plains, valleys, and river deltas (Wahrhaftig, Percentage of total ground water ----------- 22 1965). The principal mountain ranges have cores of igneous Percentage of total rural domestic ---------- 99 , . , . - , i v. j- Per capita (gal/d) ----------------- 105 and metamorphic rocks, which are overlain by younger sedi- Livestock- mentary and igneous rocks. In most of the State, the bedrock Ground water (Mgal/d)- --------------- o is covered by unconsolidated deposits of glacial and alluvial Percentage of total ground water - ----------- o . - Percentage of total livestock -------------- 0 ° ' Industrial self-supplied withdrawals: Because of its large geographic area, climatic conditions Ground water (Mgal/d)- --------------- 14 differ considerably across the State. Average annual tempera- Percentage of total ground water - ----------- 31 tures range from 10°F in northern Alaska to 45°F in the Percentage of total industrial self-supplied: fe Including withdrawals for thermoelectric power ----- 9 southeastern coastal areas; extremes range from -80° to Excluding withdrawals for thermoelectric power - - - - 11 100°F, which occur in the interior lowland. Recorded annual Irrigation withdrawals: precipitation ranges from about 5 inches (in.) on the north Ground water (Mgal/d)- - --------------- 0 ^ ' Percentage of total ground water- ------------ 0 slope of the Brooks Range to 300 in. along the southeastern Percentage of total irrigation -------------- 0 coast. A large amount of precipitation and relatively low temperatures in the coastal mountains of southeastern and south-central Alaska favor the formation and persistence of glaciers and perennial snowfields, which now cover nearly 30,000 square miles (mi2), or about 5 percent of the State. Melting snow and ice in glaciated areas provide a water source P RIN CI PA L AQUIFERS not directly related in time to local precipitation. The meltwa- Principal aquifers in Alaska consist of unconsolidated ter has a regulatory or moderating effect on streamflow alluvium and glacial deposits, and consolidated clastic and variability and, in turn, on ground-water recharge along carbonate sedimentary rocks. The aquifers are described alluvium-filled glacial valleys (Zenone and Anderson, 1978, below and in table 2; their areal distribution is shown in p. 2). figure 1. 130 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Alaska [Mgal/d = million gallons per day; gal/min = gallons per minute; ft = feet. Note: Permafrost restricts availability of ground water, especially in rocks of little permeability. Sources: Reports of the U.S. Geological Survey, Alaska Department of Environmental Conservation, and the Alaska Department of Natural Resources] Aquifer name and description Well characteristics_____ Water Depth (ft) Yield (gal/min) withdrawals Common Common May (Mgal/d) range range exceed Remarks Unconsolidated aquifers: Alluvial and glacial outwash deposits. Confined to unconfined. Bedrock aquifers: Igneous metamorphic, and sedimentary rocks. Generally unconfined. 48 50 - 200 5-10 20 Individual private-supply wells in thin alluvium or mixed glacial deposits. 100-400 50-1,000 3,000 Major supply wells in thick alluvium, glacial outwash deposits. Provides public supply at Anchorage and Fairbanks, industrial supply for Kenai Peninsula. 50 - 500 1-10 25 Source for most private wells in upland areas, particularly near Anchorage and Fairbanks. UNCONSOLIDATED AQUIFERS The greatest volume of ground water in Alaska is stored in alluvium of river valleys, including flood plains, terraces, and alluvial fans of major valleys and smaller mountain and upland valleys. Alluvial deposits in the valleys of the Yukon, the Tanana, the Kuskokwim, the Kobuk, and the Susitna Rivers have a large recharge potential because they are con- nected hydraulically to the extensive surface-water system. In the lower Tanana River basin, for example, the maximum known thickness of alluvium is 2,000 feet (ft) (Anderson, 1970), and wells less than 200 ft deep may yield as much as 3,000 gallons per minute (gal/min). Coastal basins and valleys are filled by glacial till and fine-grained glaciolacustrine materials that are interbedded with more permeable, water-worked deposits of sand and gravel. The largest and best-known ground-water system of this type is that of the Cook Inlet lowland, particularly in the Kenai and Anchorage areas, where alluvium of glacial out- wash origin that is confined by glacial, lacustrine, and estua- rine deposits yields as much as 1,500 gal/min to wells. Alluvium-filled coastal valleys along the Gulf of Alaska (such as those in the Seward area) and in mountainous southeastern Alaska (such as that of the Mendenhall River near Juneau) probably contain large, but as yet not fully explored ground-water supplies. However, freshwater aqui- fers in these areas may be connected hydraulically to the ocean, and extensive ground-water development potentially could cause saltwater intrusion. Because most ground-water development in Alaska is from unconsolidated aquifers, virtually all available water- quality data are for those aquifers. Known dissolved-solids concentrations of water from unconsolidated aquifers range from about 25 milligrams per liter (mg/L) in shallow stream- channel alluvium to 64,000 mg/L in shallow coastal wells, but most sampled ground water contains less than 250 mg/L of dissolved solids and is suitable for most uses (Feulner, Child- ers, and Norman, 1971, p. 39). Very mineralized ground water occurs in the Copper River basin (reported dissolved- solids concentrations of 2,400 mg/L in a well and 14,500 mg/L in a spring, both near Glennallen) and in many parts of the continuous permafrost zone (fig. 1). Iron is present in objectionable concentrations (more than about 0.3 mg/L of iron causes staining of laundry and plumbing fixtures) in a large percentage of shallow wells in most areas of the State. Other constituents that are present locally in undesirable concentrations include nitrate as nitrogen (as much as 60 mg/L) and arsenic (as much as 10 mg/L) at Fairbanks (John- son and others, 1978). BEDROCK AQUIFERS Glacial and alluvial deposits are either very low in permeability, thin, or absent in approximately 75 percent of Alaska. In such areas, appreciable amounts of ground water are present only in consolidated rocks. Carbonate rocks in the northeastern Brooks Range in northern Alaska provide exten- sive reservoirs for ground water. Individual springs in these rocks discharge as much as 16,000 gal/min. Sandstone and alternating strata of sand, silt, and clay are widespread throughout the State, but such rocks have been explored for water only in the western Kenai Peninsula where they are poor aquifers because of low permeability. Probably the most intensive development of bedrock aquifers is in the uplands near Fairbanks (fractured schist) and in a few places in southeastern Alaska. These rocks generally provide only modest amounts of water (well yields of 10 gal/min or less) that are adequate for single household needs. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Much of the ground-water withdrawal in Alaska occurs within the municipality of Anchorage (location 4, fig. 2), where more than one-half of the State's population resides. About 50 other communities rely solely on ground water for their supply. The only areas outside Anchorage with large- scale ground-water use are the Tanana River valley in interior Alaska (locations 1, 2, fig. 2), and the industrial complex on the Kenai Peninsula (location 5, fig. 2). The withdrawal and use of ground water are increasing with the growth of population and continuing industrial and commercial development. Analysis of observation-well data from the Anchorage, Fairbanks, and Kenai areas, however, indicates that past and present pumping has not resulted in such adverse effects as saltwater encroachment in coastal areas or excessive drawdown. A National Water Summary Alaska 131 EXPLANATION I I Unconsolidated alluvium ' ' and glacial outwash Igneous, sedimentary, and metamorphic bedrock EXPLANATION Continuous permafrost area Discontinuous permafrost area Southern limit of permafrost area B Figure 1. Principal aquifers in Alaska. A, Geographic distribution. B, Geographic distribution of permafrost areas. (See table 2 for a more detailed description of the aquifers. Sources: A, Wahrhaftig, 1965. B, Williams, 1970.) 132 National Water Summary Ground-Water Resources GROUND-WATER MANAGEMENT The Alaska Water Use Act, Alaska Statutes 46.15.010-270, was enacted in 1966 to regulate appropriation and use of water in the State. This Act gave statutory definition to the doctrine of prior appropriation (first in time, first in right) authorized by the State Constitution. The Act also established a procedure for maintaining existing rights and providing new rights to ground and surface waters of Alaska. The original regulations implementing the Water Use Act were amended extensively on December 29, 1979, and incorporated as 11 AAC 93, Water Management. Those of particular interest relate to the appropriation of water, water- well standards, and temporary water use. The latest amend- ments to the Alaska Water Use Act include legislation relating to geothermal development and reservation of water (Alaska Department of Natural Resources, 1981). Alaska's Water Quality Standards, established in Title 18, Chapter 70 of Alaska Administrative Code, identify the uses of the State's waters and set criteria, which limit man- induced pollution, to protect these water uses. Procedures and criteria for changing the identified uses of a water body are included in the standards (Alaska Department of Environmen- tal Conservation, 1979). The Alaska Department of Natural Resources (ADNR), Division of Geological and Geophysical Surveys (DGGS) is the designated State agency responsible for water-data collec- tion. The DGGS, in cooperation with the U.S. Geological Survey and other State and Federal agencies, has developed and implemented an Alaskan Water Resources Evaluation (AWARE) Plan to coordinate water-data collection and water resource study activities in the State (U.S. Geological Survey and Alaska Department of Natural Resources, Division of Geological and Geophysical Surveys, 1984). The ADNR's Division of Forest, Land and Water Man- agement, Water Management Section, is responsible for plan- ning and administering the appropriation of water in the State, and the Department of Environmental Conservation is responsible for implementation of the provisions of Alaska's Water Quality Standards. Future development, protection, and conservation of the State's water resources depend on these important functions. SELECTED REFERENCES Alaska Department of Environmental Conservation, 1979, Water quality standards: 34 p. Alaska Department of Natural Resources, 1981, Water user's hand- book: Water Management Section, Division of Forest, Land and Water Management, 48 p. Anderson, G. S., 1970, Hydrologic reconnaissance of the Tanana Basin, central Alaska: U.S. Geological Survey Hydrologic Investigations Atlas HA-319. Balding, G. O., 1976, Water availability, quality, and use in Alaska: U.S. Geological Survey Open-File Report 76-513, 292 p. Feulner, A. J., Childers, J. M., and Norman, V. W., 1971, Water resources of Alaska: U.S. Geological Survey Open-File Report, 60 p. Johnson, Paula, Wilcox, D. E., Morgan, W. D., Merto, Josephine, and McFadden, Ruth, 1978, Arsenic, nitrate, iron, and hardness in ground water, Fairbanks area, Alaska: U.S. Geological Survey Open-File Report 78-1034, 2 sheets. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. U.S. Geological Survey and Alaska Department of Natural Re- sources, Division of Geological and Geophysical Surveys, 1984, Alaska water resources evaluation, 5-year plan, 1984-1988: 40 p. Wahrhaftig, Clyde, 1965, Physiographic divisions of Alaska: U.S. Geological Survey Professional Paper 482, 52 p. Williams, J. R., 1970, Ground water in the permafrost regions of Alaska: U.S. Geological Survey Professional Paper 696, 83 p. Zenone, Chester, and Anderson, G. S., 1978, Summary appraisals of the Nation's ground-water resources Alaska: U.S. Geological Survey Professional Paper 813-P, 28 p. Prepared by Charles E. Sloan, Philip A. Emery, and Chester Zenone For additional information contact District Chief, U.S. Geological Survey, 4230 University Drive, Anchorage, AK 99508-4664 National Water Summary Alaska 133 g 1 4 o S 3 6 3 mt- 8 a Bf 9 1 10 i 12 UJ 2 Alluvial and glacial- Unconfined - outwash aquifer ~ Missing - /\ record '**\^^^ ^\^^""*""""*^^. ^^^^^ ^^ ^*s^^^ ~ - _ 1 1 1 1975 4 Alluvial and glacial- outwash aquifer Confined Ground-water withdrawals, 1980 (million gallons per day) ® 2.0 - 5 % 5.1 - 10 ^ 10.1 - 15 Location number 2 Withdrawal site 52 \5 Alluvial and glacial- Confined outwash aquifer 1965 1975 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 Geographic area Clear ....... Aquifer Alluvial and glacial-outwash . . . ... .do . ............ ... .do . ............ ... .do ............... ... .do ............... ... .do ............... Principal uses Public supply. Do. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Alaska. (Sources: Withdrawal and water-level data from U.S. Geological Survey files.) 134 National Water Summary Ground-Water Resources U.S. Geological Survey Water-Supply Paper 2275 ARIZONA Ground-Water Resources National Water Summary Arizona 135 Table 1 . Ground-water facts for Arizona [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] ___ ______________ Population served by ground water, 1980 The availability of adequate and potable water supplies in Arizona has had a great effect on the location of cities and croplands. Agriculture depends almost entirely on irrigation because annual rainfall is low. The amount of surface water available is not sufficient to meet continually increasing de- mands, thus, ground-water reservoirs are of prime importance as a source of water. Many towns and cities including the Number (thousands) - ----------------- 1,770 , , . . J.. . A , , , A . . Percentage of total population -------------- 65 second largest in the State, Tucson, depend entirely on wells From pug,ic water.s\lpp,y systerns: for water supply. Except during infrequent periods of greater Number (thousands) - --------------- 1,490 than normal streamflow, all available surface water is appro- Percentage of total population- ------------ 55 priated, and any increased water demand must be supplied by ^^umJe^tEsands) - ---------------- 280 ground water. In 1980, about 58 percent of the total water Percentage of total population - ------------ 10 supply in the State came from its ground-water reservoirs Fresh water withdrawals, 1980 ~ . . Surface water and ground water, total (Mgal/d) ------ '7,300 The principal use of ground water is for irrigation of Ground water only (Mgal/d) -------------- 4,200 crops, although municipal and industrial uses are increasing Percentage of total- ----------------- 58 steadily. Arizona ranks second in the Nation in population Percentage of total excluding withdrawals for .. ... , , __ _ ,r> thermoelectric power ---------------- 57 growth; population increased about 53 percent from 1970 to 1980 (Valley National Bank of Arizona, 1981, p. 3). As _____________Category of use population increases, some cropland is being retired in favor Public-supply withdrawals: of housing developments, and ground-water withdrawals for S^rfSX^"^ I I I I I I I I I I '- - 1 public supply are increasing. More industrial enterprises also Percentage of total public supply- ----------- 54 are being developed in the State. In 1975, less than 9 percent Per capita (gal/d) ------------------ 201 of the ground water withdrawn was used for public supply, Rin^^^thdrawals: rural, and industrial purposes (Babcock, 1977), whereas in Ground water (Mgal/d)- -------------- 32 1980 about 12 percent was used for these purposes (table 1). Percentage of total ground water - ---------- 0.8 Percentage of total rural domestic ---------- 100 PRINCIPAL AQUIFERS Per capita (gal/d) ----------------- 114 Livestock: The principal aquifers in Arizona consist of unconsolidat- Ground water (Mgal/d)- -------------- 9.8 ed alluvium, consolidated sedimentary rocks, and crystalline Percentage of total ground water - ---------- 0.2 igneous and metamorphic rocks. Arizona is divided into three lnda^^^^S^:~ ----------- 82 water provinces, which are essentially synonomous with physi- Ground water (Mgal/d)- --------------- 180 ography the Plateau uplands province in the northern part Percentage of total ground water - ------------ 4 of the State, the Basin and Range lowlands province in the Percentage of total industrial self-supplied: ' 6 H Including withdrawals for thermoelectric power - - - - 72 southern part of the State, and the Central highlands prov- Excluding withdrawals for thermoelectric power - - - - 88 ince, which is transitional between the other two provinces Irrigation withdrawals: (fig. 1). The occurrence of ground water differs greatly in Ground water (Mgal/d)- -------------- 3,700 v fc ' & . & J Percentage of total ground water - ----------- 88 each of the provinces. The aquifers in Arizona are described Percentage of total irrigation ------------- 58 according to the water province in which they occur. The aquifers also are described in table 2, from youngest to Oldest; ' The total freshwater withdrawal (as published in Solley and others, 1983) . . ,. . . has been reduced by the amount of surface water that is returned to the their area! distribution IS Shown in figure 1. Colorado River. For additional information, see U.S. Geological Survey, 1982b. PLATEAU UPLANDS In the Plateau uplands province, the principal aquifers are beds of fine-grained permeable sandstone interbedded with relatively impermeable siltstone and claystone (fig. 1, Dissolved-solids concentrations in the ground water in the table 2). The Navajo and Coconino Sandstones are two of the Plateau uplands range from 90 to about 60,000 milligrams per most important units in the province. The sandstones provide liter (mg/L). Wells that tap the sandstone aquifers in the large reservoirs for the storage of ground water, but well yields northeastern part of the area yield water that contains from are small except where the rocks have been fractured and about 200 to 25,000 mg/L of dissolved solids. In some areas, faulted. In places, the claystone and siltstone layers confine water from the sandstone aquifers contains too much dis- the water in the underlying aquifers under artesian pressure. solved solids for most uses (Kister, 1973). 136 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Arizona [Gal/min = gallons per minute; ft = feet. Source: Reports of the U.S. Geological Survey and the Arizona Department of Water Resources] Aquifer name and description Well characteristics Depth, common range (ft) Yield (gal/min) Remarks Common range May exceed Alluvial aquifers: Generally sand, gravel, silt, and clay. Occur in the Basin and Range lowlands and parts of the Central highlands. Confined and unconfined Sandstone aquifers: Mostly fine- grained sandstone units; fracturing and faulting increases permeability; in places, siltstone and claystone layers function as confining beds. Occur in parts of the Central highlands and in the Plateau uplands. Confined and unconfined. Low-yielding bedrock aquifers: Crystalline and sedimentary rocks. Permeable only where extensively fractured and faulted. Confined and unconfined. 100-2,000 50 - 2,000 50-1,000 1,000 2,500 Thickness from a few hundred to about 10,000 ft. Deposits grade in texture from large boulders near mountains to fine-grained sediments along axis of valleys. In places, dense clay beds form confining layers for permeable sand and gravel beds beneath. Provides water for most cities and extensive irri- gated areas in southern part of State. 0-50 500 Thickness from about 200 to 500 ft. Aquifers may be as much as 1,000 ft below land surface and are separated by thick, relatively impervious layers. Coconino and Navajo Sandstones pro- vide largest supply of water for all uses in central and northern parts of State. 0.5 - 2 200 These rocks are generally not considered to be aquifers but do supply usable quantities of water to individual sources for domestic supp'ly in rural areas. BASIN AND RANGE LOWLANDS The Basin and Range lowlands province is characterized by rugged mountain ranges separated by broad alluvium-filled basins. The mountains consist of crystalline and consolidated sedimentary rocks that contain usable amounts of water only where extensively fractured or faulted. The thick alluvial deposits in the basins are the major aquifers and provide storage for large amounts of ground water (fig. 1; table 2). The deposits, which consist of sand, gravel, silt, clay, evapor- ites, and volcanic rocks range in thickness from a few hundred to about 10,000 feet (ft). The capacity of the materials to store and transmit water differs widely among the various basins and in different parts of the same basin. Thick clay and silt beds at various depths can restrict the movement of ground water and decrease well yields. In places, these clay or silt beds form confining layers, and water in the underlying permeable beds may locally be under artesian pressure. The block diagram in figure 1 shows a typical configuration of these aquifers. The chemical quality of the ground water in the Basin and Range lowlands generally is suitable for all uses. Dissolved- solids concentrations of water in the alluvial basins generally are less than 1,000 mg/L. Brackish water that which con- tains between 1,000 and 10,000 mg/L of dissolved solids is present mainly in areas along and near the Gila River, along the southernmost reach of the Colorado River, and near the towns of Willcox (Willcox basin), Casa Grande (lower Santa Cruz basin), and Tucson (upper Santa Cruz basin) (Kister, 1973). Recharge to the aquifers in the Basin and Range lowlands is limited by small amounts of precipitation and large evapora- tion rates. Recharge from direct infiltration of precipitation is negligible. Infiltration of runoff from the adjacent mountain areas, at mountain fronts, and in stream channels probably is the most important source of recharge to the aquifers in the alluvial basins (Halpenny and others, 1952, p. 16). In a few basins, the ground-water reservoir is recharged from perennial reaches of through-flowing streams; for the most part, streams in the area are ephemeral and recharge takes place only during times of flow. Some water is recharged by seepage from irrigated fields and from unlined canals. CENTRAL HIGHLANDS The Central highlands province is a mountainous area that separates the Plateau uplands from the Basin and Range lowlands. The province consists principally of rugged, sharply pinnacled ranges and volcanic mountains. The igneous, metamorphic, and consolidated sedimentary rocks that form the core of the province contain usable amounts of water only where fractured or faulted. A few valleys in the province are filled with alluvium that provides minor amounts of water. Available data indicate the ground water in the Central highlands generally contains less than 1,000 mg/L of dissolved solids, although some springs yield saline water to streams (Kister, 1973). 114° National Water Summary Arizona 137 37 50 EXPLANATION I j Alluvial aquifers -- Locally may include I___j evaporite deposits and volcanic rocks Sandstone aquifers I___I Low-yielding bedrock aquifers Water province boundary sw* * '''-v- /-?E~-<L -^5V&- \^^-*i& Figure 1. Principal aquifers in Arizona. A, Geographic distribution. B, Physiographic diagram. C, Block diagram showing typical alluvial deposits aquifer. (See table 2 for more detailed description of aquifers. Sources: A, Anderson, 1980; Cooley, 1963. B, Raisz, 1954. C, Compiled by N. D. White and T. W. Anderson from U.S. Geological Survey files.) 138 National Water Summary Ground-Water Resources GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS The Basin and Range lowlands province is the most developed of the three water provinces. In 1980, nearly 96 percent of the total ground water withdrawn in the State was withdrawn in this province, and about 84 percent of the water was used for the irrigation of crops (U.S. Geological Survey, 1982a). The Salt River Valley and the lower Santa Cruz basin are, and have been for many years, the areas of largest use (fig. 2). The other areas for which ground-water withdrawal is shown in figure 2 also use large amounts of ground water principally for irrigation. Through 1980, nearly 180 million acre-feet of water had been withdrawn from the ground-water reservoirs in the province (U.S. Geological Survey, 1982b). The with- drawal is balanced only partly by recharge. In nearly all the areas shown in figure 2, and in other areas as well, water levels generally are declining in response to the withdrawal of ground water at a rate in excess of the rate of replenishment. In part of the Salt River Valley, a water-level decline of 400 ft occurred from 1923 to 1976; most of the decline has occurred since the 1940's when intense ground-water development began (Laney and others, 1978). From 1923 to 1977, declines of nearly 500 ft occurred in part of the lower Santa Cruz basin (Konieczki and English, 1979). Land subsidence and earth fissures have occurred in some areas of large water-level decline. In an area of about 120 square miles in the lower Santa Cruz basin, the land subsided more than 7 ft from 1952 to 1977 (Laney, Raymond, and Winikka, 1978). Hydrographs for the Willcox and lower Santa Cruz basins and west Salt River Valley (location 7, 2, and 1A, respectively, fig. 2) show water-level changes since 1950 that are the result of the removal of water from storage in the alluvial deposits, although the rate of decline has decreased in some areas since about 1965 to 1970 as a result of increased recharge or a reduction in pumpage. The hydrograph for a well near east Salt River Valley (location IB, fig. 2) shows the effect of unusually high flows in the Salt River in recent years (Mann and Rohne, 1983) that have recharged the aquifer. In the Plateau uplands and the Central highlands prov- inces, ground-water development is small compared to that in the Basin and Range lowlands province. The use of ground water is limited to irrigation of a few thousand acres, scattered industrial and utility sites, and a few small population centers. For the most part, the small amount of ground water with- drawn has not resulted in any discernible pattern of rise or decline in water levels. However, some decline has occurred in places such as Little Chino Valley in the Central highlands. In the irrigated part of this valley, water levels in a few wells declined as much as 75 ft from 1940 to 1982 (Remick, 1983). Elsewhere in the two provinces, water levels have declined only a few feet. GROUND-WATER MANAGEMENT As much of the foregoing material indicates, Arizona's major water problem is the imbalance between the water needed for various uses and the available supply. The Arizona Ground-Water Management Act, enacted on June 12, 1980, is the first comprehensive legislative framework for managing the ground-water resources of the State (Arizona Department of Water Resources, 1982). The ground-water code is found in the Arizona Revised Statutes, Sections 45-401 through 45-637. Before this Act, only the Critical Ground-Water Code of 1948 had attempted to alleviate the problem of overdraft. That code provided for the establishment of criti- cal ground-water areas in which the cultivation of new irrigat- ed acreage was prohibited; however, the ground-water over- draft problem was not reduced by the code. The 1980 Act created the Department of Water Resources and made it responsible for administering the law's complex provisions. The Act established four Active Management Areas (AMA's) areas in which intensive ground-water manage- ment is needed because of the large and continuous ground- water overdraft. Within the AMA's, the law requires a 45-year water-conservation and water-management program. The management goal is "safe yield" by the year 2025. Safe yield is the concept whereby long-term ground-water discharge is equal to ground-water recharge. Further details of the ground-water code for Arizona may be obtained from the Arizona Department of Water Resources. SELECTED REFERENCES Anderson, T. W., 1980, Study plan for the regional aquifer-system analysis of alluvial basins in south-central Arizona and adjacent states: U.S. Geological Survey Open-File Report 80-1197, 22 p. Arizona Department of Water Resources, 1982, Progress report Implementation of the 1980 ground-water management code: State of Arizona Department of Water Resources, 5 p. Babcock, H. M., 1977, Annual summary of ground-water conditions in Arizona, spring 1975 to spring 1976: U.S. Geological Survey Water-Resources Investigations 77-10. Brown, S. G., 1976, Preliminary maps showing ground-water re- sources in the lower Colorado River region, Arizona, Nevada, New Mexico, and Utah: U.S. Geological Survey Hydrologic Investigations Atlas HA-542. Cooley, M. E., 1963, Hydrology of the Plateau uplands province, in White, N. D., Stulik, R. S., Morse, E. K., and others, Annual report on ground water in Arizona, spring 1962 to spring 1963: Arizona State Land Department Water Resources Report No. 15, 136p. Halpenny, L. C., and others, 1952, Ground water in the Gila River basin and adjacent areas, Arizona A summary: U.S. Geologi- cal Survey open-file report, 224 p. Kister, L. R., 1973, Quality of ground water in the lower Colorado River Region, Arizona, Nevada, New Mexico, and Utah: U.S. Geological Survey Hydrologic Investigations Atlas HA-478. National Water Summary Arizona 139 200 220 240 260 280 300 320 340 360 380 1A Alluvial aquifer Unconfined I I I I I I I 1955 1965 1975 1985 40 60 80 100 120 14° 160 ieo 200 220 Unconfined 1945 1965 1975 1985 -1 ieo 5 200 fc 220 £ 240 | aeo I 280 x 300 '- 2 Alluvial aquifer Unconfined Missing record 1945 1955 1975 1985 60 80 100 120 140 160 180 200 220 240 7 Alluvial aquifer Unconfined 1945 1955 1975 1985 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) O 50-200 O 201 - 500 O 501 - 800 O 801 - 1000 Location number 3 Withdrawal site WITHDRAWAL SITES [Aquifers are all in alluvial deposits] No. on map 1A 1B 2 3 4 5 6 7 8 9 Geographic area West Salt River Valley East Salt River Valley . . . Lower Santa Cruz basin . . Upper Santa Cruz basin . . Gila River, Painted Rock to Texas Hill. Gila River, Texas Hill to Dome. Principal uses Irrigation, public supply. Do. Irrigation. Irrigation, public supply. Irrigation. Do. Do. Do. Do. Do. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Arizona. (Sources: Withdrawal and water-level data from U.S. Geological Survey files.) 140 National Water Summary Ground-Water Resources Konieczki, A. D., and English, C. S., 1979, Maps showing ground- water conditions in the lower Santa Cruz area, Final, Pima, and Maricopa Counties, Arizona 1977: U.S. Geological Survey Water-Resources Investigations 79-56. Laney, R. L., Raymond, R. H., and Winikka, C. C., 1978, Maps showing water-level declines, land subsidence, and earth fissures in south-central Arizona: U.S. Geological Survey Water-Re- sources Investigations 78-83. Laney, R. L, Ross, P. P., and Littin, G. R., 1978, Maps showing ground-water conditions in the eastern part of the Salt River Valley area, Maricopa and Pinal Counties, Arizona 1976: U.S. Geological Survey Water-Resources Investigations 78-61. Mann, L. J., and Rohne, P. B., 1983, Streamflow losses and changes in ground-water levels along the Salt and Gila Rivers near Phoenix, Arizona February 1978 to June 1980: U.S. Geologi- cal Survey Water-Resources Investigations Report 83-4043, 11 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Remick, W. H., 1983, Maps showing ground-water conditions in the Prescott Active Management Area, Yavapai County, Arizona 1982: Arizona Department of Water Resources Hydrologic Map Series Report No. 9. Solley, W. B., Chase E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. U.S. Geological Survey, 1982a, Annual summary of ground-water conditions in Arizona, spring 1980 to spring 1981: U.S. Geologi- cal Survey Water-Resources Investigations Open-File Report 82-368. __1982b, Water resources data for Arizona, water year 1980: U.S. Geological Survey Water Resources Data Report AZ-80-1, 568 P- Valley National Bank of Arizona, 1981, Arizona statistical review: Valley National Bank of Arizona, Economic Research Depart- ment, 37th annual edition, 84 p. Prepared by Natalie D. White and Thomas W. Anderson For further information contact District Chief, U.S. Geological Survey, 300 W. Congress Street, Tucson, AZ 85701-1393 U.S. Geological Survey Water-Supply Paper 2275 ARKANSAS Ground-Water Resources National Water Summary Arkansas 141 Table 1. Ground-water facts for Arkansas [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Sources: Population data from Arkansas Industrial Development Foundation, 1981 (unpublished data); withdrawal data from Hall and Holland, 1984] Population served by ground water, 1981 Ground water plays a major role in satisfying the water- supply needs in Arkansas. Ground-water sources provide 81 percent of the State's water for irrigation, public and rural supplies, and industrial uses (table 1). The largest withdrawal of ground water [3,800 million gallons per day (Mgal/d)] is for irrigation, mostly in the eastern part of the State. Nearly all municipal and industrial supplies in the southeastern one-half ____________________________________ of the State are obtained from ground-water sources. Ground Number (thousands) - ----------------- 1,440 water provides 330 Mgal/d for self-supplied industries and 155 Percentage of total population -------------- 50 Mgal/d for public and rural domestic supplies. One-half of From public water-supply systems: the population of the State depends on ground water as a Number (thousands) ----------------- 819 source of drinking water. Between .975 and 1980, the use of Ta££3£££gS%SSZ'- ------------ 28 ground water in the State increased 56 percent (Holland and Number (thousands) ----------------- 621 Ludwig, 1981, p. 25). Most of the ground water withdrawn Percentage of total population- ------------ 22 (88 percent) is used for irrigation. Freshwater withdrawals, 1981 GENERAL SETTING Surface water and ground water, total (Mgal/d) ----- 33,000 .,..,,,. , - , Ground water only (Mgal/d) -------------- 4,300 Arkansas is divided physiograpmcally into two almost Percentage of total- ----------------- 13 equal areas the Gulf Coastal Plain and the Interior High- Percentage of total excluding withdrawals for lands (fig. 1). The occurrence of ground water is associated thermoelectric power ---------------- 81 closely with the types of rocks that underlie each physio- Category of use graphic area. Ground water is abundant in the Gulf Coastal _ ,.. ; 7~. : fL. . , t . . . . . , T . TT . ,, , Public-supply withdrawals: Plain but is relatively scarce in the Interior Highlands. Ground water (Mgal/d)- --------------- 100 The Gulf Coastal Plain, which encompasses approxi- Percentage of total ground water- ------------ 2 mately 27,000 square miles (mi2) in the southeastern one-half Percentage of total public supply- ----------- 42 of Arkansas, is underlain by thick alluvial deposits and by Per caPita (gal/d) ------------------ 127 gently dipping unconsolidated and semiconsolidated sedi- Rur^PeP{fcwithdrawals: ments. The sediments that comprise the Gulf Coastal Plain Ground water (Mgal/d)- -------------- 55 are of marine and continental origin and consist of alternating Percentage of total ground water ------------ i sequences of gravel, sand, silt, and clay, with lenses of Percentage of total rural domestic ---------- 100 limestone and lignite. In general, the marine deposits are Per capita (gal/d) ----------------- 89 composed of clays that confine water in the aquifers. Livestock: The Interior Highlands, which encompasses about 31,000 ^^^S^S^^'. -' I I I -" I -" I I -" - l mi in the northwestern one-half of the State, is underlain by Percentage of total livestock ------------- 36 thick sequences of consolidated rocks that consist mostly of Industrial self-supplied withdrawals: limestone, dolomite, sandstone, and shale. The rocks are Ground water (Mgal/d)- --------------- 330 extremely folded and faulted, and their primary porosity has Percentage of total ground water- ------------ 8 been reduced greatly by compaction and cementation (Cor- "S&'*S£££g?££SZ& tom -----, dova, 1963). Water occurs primarily in fractures in the sand- Excluding withdrawals for thermoelectric power - - - - 55 stone and in solution openings in the carbonates. Irrigation withdrawals: Precipitation is the source of recharge to the ground- Ground water (Mgal/d)- -------------- 3,800 water system in Arkansas. Precipitation averages 49 inches Percentage of total ground water- ----------- 88 (in.) (1951-80) annually and ranges from 39 in. near Fort Percentage of total irrigation ------------- 86 Smith to 59 in. in the higher elevations in west-central Arkan- sas. Of the 49 in. of precipitation that falls on the land surface, an average of about 2 in. recharges the ground-water system. The recharge rate differs from place to place, depend- important locally, these six aquifers are regionally significant, mg on the permeability of the surficial material. In the eastern andj except for rural domestic suppiies, they constitute the part of the State, where the alluvial aquifer is covered by thick source of neady all ground.water withdrawals in the State, clay, the recharge rate is only about 0.4 in. per year (Broom The aquifers are described below and in table 2, from young- and Lyford, 1981). est to oidest; their areaj distribution is shown in figure 1. PRINCIPAL AQUIFERS Most of the ground-water supplies in the State are ob- tained from six aquifers or aquifer systems the alluvial, the Cockfield, the Sparta Sand, the Wilcox, the Nacatoch Sand, and the Ozark. Although other ground-water sources may be ALLUVIAL AQUIFER Alluvium is the principal source of water for irrigation. Alluvial deposits blanket much of eastern Arkansas, the Red River Valley in southwestern Arkansas, and isolated areas along the Arkansas River in the Interior Highlands (fig. 1). The alluvium is as much as 250 feet (ft) thick in parts of 142 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Arkansas [Gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Reports of the U.S. Geological Survey and Arkansas Geological Commission] Well characteristics Aquifer name and description Depth (ft) Yield (gal/min) Common May Common May range exceed range exceed Remarks Alluvial aquifer: Sand and gravel at the base grades upward to silt and clay near the surface. Confined to unconfined. Cockfield aquifer: Interbedded fine to medium sand, clay, and lignite. Confined except in the outcrop. Sparta Sand aquifer: Massive fine to medium sand with interbedded clay and lignite. Generally confined. 100-150 350 - 500 200 700 1,000-2,000 5,000 100-350 500 500-1,000 1,200 500-1,500 3,000 Wilcox aquifer: Fine to medium sand, silt, clay, and lignite. Generally confined. Nacatoch Sand aquifer: Massive cross-bedded sand, limestone lenses, and calcareous clay. Confined. Ozark aquifer: Sandstone and sandy dolomite. Confined. 750-1,100 1,500 50-500 2,000 500-800 1,100 150-300 500 600-2,400 3,000 150-300 500 Water used primarily for irrigation. Generally hard and contains much iron. Intruded by saline water in places. Water-level declines of as much as 80 ft in Arkansas, Cross, and Poinsett Counties. Used mostly for domestic purposes and for municipal supplies in Chicot and Desha Counties. Water is soft, sodium bicarbonate or sodium chloride type. Contains as much as 1,800 mg/L of chloride in parts of extreme southeastern Arkansas. Equivalent to Memphis Sand ("500- foot sand") in northeastern Arkansas. Principal source of water for municipal and industrial uses in much of the Gulf Coastal Plain south of latitude 35°N. Water-level declines of as much as 320 ft in Columbia, Union, and Jefferson Counties. Declines have induced localized saline-water contamination in places. Saline downdip in southeastern Arkansas. Greatest yields in eastern and northeastern Arkansas. Known as " 1,400-foot sand" near Memphis, Tenn. Water a soft, sodium bicarbonate type. Saline in downdip areas. Equivalent to Fort Pillow Sand in Tennessee. Equivalent to the McNairy aquifer in Missouri. Contains freshwater in parts of southwestern and northeastern Arkansas. Used mostly for municipal and industrial supplies. Water is a soft, sodium bicarbonate type. Saline in downdip areas. Includes the Roubidoux Formation and Gunter Sandstone Member of the Van Buren Formation. Principal source of water for municipal and industrial wells in northern Arkansas. Yields hard or very hard calcium-bicarbonate-type water. eastern Arkansas and is composed of coarse sand and gravel at the base that grades upward to silt and clay near the surface. Wells in the alluvium generally yield from 1,000 to 2,000 gallons per minute (gal/min) but may yield as much as 5,000 gal/min. Water in the alluvium generally is hard, averaging 246 mg/L of hardness as calcium carbonate, and contains iron in excess of 1.0 mg/L (Boswell and others, 1968). In parts of Chicot, Desha, Lincoln, Monroe, and White Counties, the water contains as much as 3,750 mg/L of dissolved solids, which makes it unsuitable for irrigation. The saline water is believed to have migrated upward from underlying, saline- water-bearing beds through faults or abandoned oil test wells. A similar problem exists in the Red River alluvium in parts of Miller and Lafayette Counties (Ludwig, 1972). National Water Summary Arkansas 143 50 100 MILES K "" V-1 Alluvial aquifers I:-:V:-.=I Cockfield aquifer I I Sparta Sand aquifer I I Wilcox aquifer f Nacatoch Sand aquifer Ozark aquifer system -- ' Present only in the subsurface in Arkansas Not a principal aquifer A A' Trace of cross section Sea level - -1000' - -2000' Figure 1. Principal aquifers in Arkansas. A, Geographic distribution. B, Physiographic diagram and divisions. C, Generalized cross section (A-A 1). (See table 2 for a more detailed description of the aquifers. Sources: A,C, Ludwig, 1972 and compiled by A. H. Ludwig from U. S. Geological Survey files. B, Raisz, 1954.) 144 National Water Summary Ground-Water Resources COCKFIELD AQUIFER The Cockfield aquifer is at or near the surface of the Coastal Plain of southeastern Arkansas. The aquifer, which consists of interbedded fine to medium sand, clay, and lignite, is as much as 400 ft thick in Chicot and Desha Counties. The water generally is suitable for most municipal and industrial uses but, in places, contains iron in excess of 0.3 mg/L, the criterion established by the national drinking-water regula- tions (U.S. Environmental Protection Agency, 1982). Yields from wells in the Cockfield may exceed 500 gal/min. SPARTA SAND AQUIFER The Sparta Sand aquifer is the principal source of water for public and industrial supplies in much of southern and southeastern Arkansas. The aquifer also is being tapped increasingly for irrigation in Arkansas County. The Sparta, which is composed of massive fine to medium sands that contain interbedded clay lenses, is as much as 800 ft thick. Wells that tap the Sparta generally yield from 500 to 1,500 gal/min but may yield as much as 3,000 gal/min. North of about latitude 35°N, the Sparta Sand becomes part of a thick sand sequence known as the Memphis Sand (Hosman and others, 1968). The Memphis Sand is used as a source of water for Memphis, Tenn., but commonly is not used in Arkansas because the water generally contains concentrations of iron greater than 0.9 mg/L. WILCOX AQUIFER The Wilcox aquifer occurs throughout most of the Coast- al Plain in Arkansas but is a major source of water only in northeastern Arkansas where it is known as the "1,400-foot sand." Wells that tap the Wilcox aquifer in Crittenden and Mississippi Counties yield as much as 2,000 gal/min. With- drawals are primarily for public and industrial supplies. In southwestern Arkansas, the unit is composed of fine sand and silt and does not yield significant amounts of water. The Wilcox aquifer contains freshwater (less than 1,000 mg/L of dissolved solids) to a depth of 1,500 ft below land surface in Crittenden County. NACATOCH SAND AQUIFER The Nacatoch Sand aquifer underlies the Gulf Coastal Plain part of the State but contains freshwater only in parts of the northeast and southwest. It is used primarily for public and industrial supplies in Clay, Greene, Randolph, and Law- rence Counties in the northeast and in Nevada, Hempstead, and Little River Counties in the southwest. The Nacatoch Sand aquifer yields as much as 500 gal/min of water to wells in Clay and Greene Counties (Hines and others, 1972). How- ever, water-level declines of more than 40 ft have been noted at Prescott in Nevada County as a result of large municipal withdrawals (Ludwig, 1972). Water in the Nacatoch Sand aquifer generally is soft (less than 30 mg/L of hardness as calcium carbonate) and contains less than 500 mg/L dissolved solids in the freshwater areas. OZARK AQUIFER The Ozark aquifer consists primarily of dolomite, sandy dolomite, and sandstone and is the only significant aquifer system, except for the Arkansas River alluvium in the Interior Highlands. It is used in northern Arkansas in an area from Benton and Washington Counties to Randolph and Lawrence Counties (fig. 1). The system includes the Roubidoux Forma- tion and the Gunter Sandstone Member of the Van Buren Formation, which do not crop out in Arkansas. These strata are the principal source of ground water in the northern part of the State. The Roubidoux is 100 to 250 ft thick and is present at depths ranging from 600 ft at the Arkansas-Mis- souri State line to about 2,300 ft at the southern limits of the area of use. The Gunter Sandstone Member is about 50 ft thick and is 300 to 600 ft below the Roubidoux Formation. The massive dolomites between these aquifers do not yield water. Together, the Roubidoux and Gunter aquifers yield as much as 500 gal/min to wells, but generally yield 150 to 300 gal/min (Lamonds, 1972). Water in the Ozark aquifer system contains less than 1,000 mg/L of dissolved solids throughout the area shown in figure 1. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Areas of major ground water withdrawals are shown in figure 2. Most of the ground water used in the State (88 percent) is for irrigation, primarily irrigation of rice. Irriga- tion is practiced extensively in the Mississippi River alluvial plain, which encompasses all or parts of 27 counties in eastern Arkansas. Irrigation also is important in parts in the Red River Valley in southwestern Arkansas and in the Arkansas River Valley between Little Rock and Fort Smith. Irrigation withdrawals for the 27 counties in eastern Arkansas (locations 1-27, fig. 2) were 3,718 Mgal/d in 1981, or about 99 percent of the total irrigation withdrawals in the State. Irrigation with- drawals for the Grand Prairie, a very productive rice-growing area, are represented by locations 1 to 3. The largest single withdrawal rate was 356 Mgal/d, mostly in western Poinsett County (location 16, fig. 2). Irrigation in western Poinsett and adjacent counties has increased significantly in recent years. Large sustained ground-water withdrawals for irrigation have caused significant water-level declines in some areas. Water levels in the Grand Prairie and in western Cross, Poinsett, and Craighead Counties are as much as 115 ft below land surface. Only about 20 to 50 ft of saturated thickness remains in some places, and irrigators either are drilling deeper and more costly wells into underlying formations or are developing surface-water sources. Water levels in wells throughout much of the alluvial aquifer have declined at the annual rate of 0.3 to 0.5 ft. Water levels in wells in western Craighead County have declined at the annual rate of 0.75 feet (location 5, fig. 2) as the result of large irrigation withdrawals in the area (Hines and others, 1972). Water levels in wells in the Sparta Sand aquifer have declined substantially in several areas as a result of large municipal and industrial withdrawals. At El Dorado in Union County (location 29, fig. 2), water levels, which have declined about 60 ft since 1955 and about 320 ft since pumping began in that area, are at or near the top of the aquifer. Continued concentrated withdrawals in the intensively pumped areas may result in dewatering of the aquifer and in a reduction of well yield. Similar conditions exist at Magnolia in Columbia County (location 30, fig. 2) and at Pine Bluff in Jefferson County (location 28, fig. 2). The cone of depression at Pine Bluff has extended northeastward, toward the Grand Prairie, as a result of large withdrawals in recent years from the Sparta Sand aquifer for irrigation in Arkansas County. The decline in freshwater hydraulic head of the aquifer at El Dorado has allowed the movement of saline water into several industrial wells in the area. National Water Summary Arkansas 145 o »" tt 40 g 50 3 60 3 70 * 80 UJ £ 90 ^ 100 <* n ° x *20 S 1 Alluvial aquifer Unconfined - - - - - v. .^ S"s-"x^ ^ \ - i i \ \ i i i i i i i 1925 1935 1945 1955 1965 1975 1985 O iu j| 20 g 30 3 40 3 so ? 60 UJ ffi 70 ccg 80 * 90 e^ too & 5 Alluvial aquifer Unconfined - - : >^ : ^\ _ - i i i i i i i i i i i 1925 1935 1945 1955 1965 1975 )985 100 120 140 160 180 200 220 240 260 280 28 Sparta Sand aquifer Confined i I i i i i i i i i i 1925 1935 1945 1955 1965 1975 1985 8 270 <g 280 § ° 290 300 § 310 JH 320 UJ E 330 (I 340 * 350 t 360 29 Sparta Sand aquifer Confined EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) O 1 - 10 O 11 - 100 O 101 - 250 Q 251 - 500 Location number ©4 Withdrawal site 1925 1935 1945 1955 1965 1975 1985 WITHDRAWAL SITES No. on 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Geographic area Arkansas County ........ Prairie County. ......... Clay County ........... Craighead County. ....... Crittenden County ....... Cross County .......... Greene County ......... Independence County . . . . . Jackson County ......... Lawrence County ........ Lee County ........... Mississippi County ....... Monroe County ......... Phillips County ......... Poinsett County. ........ Randolph County. ....... St. Francis County ....... White County .......... Woodruff County ........ Ashley County ......... Chicot County. ......... Desha County .......... Drew County .......... Jefferson County ........ Lincoln County ......... Pulaski County ......... Jefferson County ........ E| Dorado area ......... Magnolia area .......... Northeastern Arkansas area . . Southwestern Arkansas area . . Northern Arkansas area .... Aquifer Alluvial, Sparta Sand .... Alluvial. ........... ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ Sparta Sand ......... ... .do ............ ... .do ............ Wilcox, Nacatoch Sand. . . Nacatoch Sand ....... Ozark. ............ Principal uses Irrigation. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Do. Municipal- industrial. Do. Do. Do. Do. Do. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Arkansas. (Sources: Withdrawal data from Hall and Holland, 1984; water-level data from U.S. Geological Survey files.) 146 National Water Summary Ground-Water Resources GROUND-WATER MANAGEMENT Ground-water management in Arkansas is currently in the data-collection and planning stages. Several State and local agencies have limited or inferred jurisdiction over ground water. The Arkansas Department of Health is respon- sible for the protection of municipal and rural drinking supplies and regulates the construction and use of septic tanks. The Arkansas Soil and Water Conservation Commission is responsible for the Arkansas State Water Plan, which evalu- ates surface- and ground-water resources, problems, and management strategies. The Commission also is the leading proponent of the Arkansas Water Code Bill, which, if enact- ed, will require registration of ground-water withdrawals. The Arkansas Geological Commission provides the geologic and hydrologic data for the State's water-resources planning. The Arkansas Department of Pollution Control and Ecology is responsible for control of ground-water quality and execution of federally delegated programs, such as the Underground Injection Control Program, the Resource Conservation and Recovery Act, the Clean Water Act, and construction-grant programs. The Arkansas Oil and Gas Commission shares responsibility with the Arkansas Department of Pollution Control and Ecology over the Underground Injection Control Program. The Water Well Committee regulates a well-driller licensing program and maintains well-construction standards and files on well-completion reports. The Arkansas Plant Board, the Forestry Commission, and the Cooperative Exten- sion Service also have responsibilities that indirectly affect ground water. SELECTED REFERENCES Albin, D. R., 1964, Geology and ground-water resources of Bradley, Calhoun, and Ouachita Counties, Arkansas: U.S. Geological Survey Water-Supply Paper 1779-G, 32 p. Albin, D. R., Hines, M. S., and Stephens, J. W., 1967, Water resources of Jackson and Independence Counties, Arkansas: U.S. Geological Survey Water-Supply Paper 1839-G, 29 p. Bedinger, M. S., and Sniegocki, R. T., 1976, Summary appraisals of the Nation's ground-water resources Arkansas-White-Red re- gion: U.S. Geological Survey Professional Paper 813-H, 31 p. Boswell, E. H., Cushing, E. M., and Hosman, R. L., 1968, Quater- nary aquifers in the Mississippi embayment, with a discussion of Quality of the water, by H. G. Jeffery: U.S. Geological Survey Professional Paper 448-E, 15 p. Boswell, E. H., Moore, G. K., MacCary, L. M., and others, 1965, Cretaceous aquifers in the Mississippi embayment, with discus- sions of Quality of the water by H. G. Jeffery: U.S. Geological Survey Professional Paper 448-C, 37 p. Broom, M. E., and Lyford, F. P., 1981, Alluvial aquifer of the Cache and St. Francis River basins, northeastern Arkansas: U.S. Geological Survey Open-File Report 81-476, 48 p. Cordova, R. M., 1963, Reconnaissance of the ground-water resources of the Arkansas Valley region, Arkansas: U.S. Geological Survey Water-Supply Paper 1669-BB, 33 p. Halberg, H. N., Bryant, C. T., and Hines, M. S., 1968, Water resources of Grant and Hot Spring Counties, Arkansas: U.S. Geological Survey Water-Supply Paper 1857, 64 p. Halberg, H. N., 1977, Use of water in Arkansas, 1975: U.S. Geologi- cal Survey Open-File Report 76-791, 28 p. Hall, A. P., and Holland, T. W., 1984, Water use in Arkansas, 1981: U.S. Geological Survey Water-Resources Investigations Report 84-4070, [map]. Hines, M. S., Plebuch, R. O., and Lamonds, A. G., 1972, Water resources of Clay, Greene, Craighead, and Poinsett Counties, Arkansas: U.S. Geological Survey Hydrologic Investigations Atlas HA-377. Holland, T. W. and Ludwig, A. H., 1981, Use of water in Arkansas, 1980: Arkansas Geological Commission Water Resources Sum- mary No. 14, 30 p. Hosman, R. L., 1982, Outcropping Tertiary units in southern Arkan- sas: U.S. Geological Survey Miscellaneous Investigations Series Map 1-1405. Hosman, R. L., Long, A. T., Lambert, T. W., and others, 1968, Tertiary aquifers in the Mississippi embayment, with discussions of Quality of the water, by H. G. Jeffery: U.S. Geological Survey Professional Paper 448-D, 45 p. Lamonds, A. G., 1972, Water-resources reconnaissance of the Ozark Plateaus Province, northern Arkansas: U.S. Geological Survey Hydrologic Investigations Atlas HA-383. Lamonds, A. G., Hines, M. S., and Plebuch, R. O., 1969, Water resources of Randolph and Lawrence Counties, Arkansas: U.S. Geological Survey Water-Supply Paper 1879-B, 45 p. Ludwig, A. H., 1972, Water resources of Hempstead, Lafayette, Little River, Miller, and Nevada Counties, Arkansas: U.S. Geological Survey Water-Supply Paper 1998, 41 p. Plebuch, R. O., and Hines, M. S., 1967, Water resources of Pulaski and Saline Counties, Arkansas: U.S. Geological Survey Water- Supply Paper 1839-B, 25 p. __1969, Water resources of Clark, Cleveland, and Dallas Counties, Arkansas: U.S. Geological Survey Water-Supply Paper 1879-A, 32 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C..U.S. Geological Survey, 417 p. Sniegocki, R. T., 1964, Hydrology of a part of the Grand Prairie region, Arkansas: U.S. Geological Survey Water-Supply Paper 1615-B,72 p. U.S. Environmental Protection Agency, 1982, Secondary maximum contaminant levels (section 143.3 of part 143, National Second- ary Drinking-Water Regulations): U.S. Code of Federal Regula- tions, Title 40, Parts 100-149, revised as of July 1, 1982, p. 374. Prepared by Augustine H. Ludwig with exception of section on "Ground-Water Management" written by Randy Young, Arkansas Soil and Water Conservation Commission, Little Rock, Arkansas. For further information contact District Chief, Water Resources Division, U.S. Geological Survey, 700 West Capitol Avenue, Little Rock, AR 72201 U.S. Geological Survey Water-Supply Paper 2275 &CALIFORNIA Ground-Water Resources National Water Summary California 147 Table 1. Ground-water facts for California [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Sources: Total with- drawals from California Department of Water Resources (1983). Category of use numbers revised and extrapolated from Solley, Chase, and Mann (1983) to be consistent with California Depart- ment of Water Resources total] Population served by ground water, 1980 Ground water is an abundant natural resource in Califor- nia and accounts for 39 percent of all freshwater withdraw- als more than 14 billion gallons per day (bgd) (table 1). More than 10 million people, 46 percent of the total popula- tion, are served by ground-water supplies. Even more signifi- cantly, 12.5 bgd of ground water is withdrawn for irrigation, 39 percent of the total amount of water withdrawn for irriga- tion. The geography and climate of California are the domi- nant factors controlling the State's water development. Gener- ally, rainfall exceeds potential evapotranspiration in the north Number (thousands) - ---------------- 10,950 but is less than potential evapotranspiration in the south. The Percentage of total population -------------- 46 principal cemers of popu.ation and agriculture are mostly in FmmN^t^^?< :. ........... 9>580 the water-deficient areas. Many of the valleys and plains of Percentage of total population - ------------ 40 the water-deficient areas, however, are underlain by produc- From rural self-supplied systems: live aquifers. Historically, ground water was the dominant Number (thousands) ---------------- 1,370 source of supply, and the prevailing opinion was that these Percentage of total population - ------------- 6 supplies were unlimited. The eventual realization that they __________Freshwater withdrawals, 1980_________ were not unlimited was an important factor in the decisions Surface water and ground water, total (Mgal/d) - - - - - 38,000 that led to the large-scale importation from the water-abun- Ground water only (Mgal/d) ------------- 14,600 dant areas of the north to the water-deficient areas of the Percentage of total- ----------------- 39 south. Percentage of total excluding withdrawals for The quality of water from the major aquifers of Califor- thermoelectric power ---------------- 38 nia generally is good. In many places, however, dissolved- _____________Category of use_____________ solids concentrations exceed the U.S. Environmental Protec- Public-supply withdrawals: tion Agency criterion of 500 milligrams per liter (mg/L) for Ground water (Mgal/d)- -------------- 1,300 drinking water, but, nevertheless, the water is suitable for Percentage of total ground water- ------------ 9 irrigation or industrial use. Many aquifers are adjacent to the Percentage onotal public supply- ----------- ^46 ocean or deposits containing saline water, where pumping may Rural-supply^Shdrawals" ---------------- cause saline-water intrusion. Domestic: Ground water (Mgal/d)- -------------- 90 Percentage of total ground water ----------- 0.6 GENERAL SETTING Percentage of total rural domestic ---------- 93 Precipitation in California is extremely variable. Mean Livestock- annual precipitation ranges from more than 40 inches (in.) in Ground water (Mgal/d)- -------------- 25 much of the mountainous areas of central and northern Percentage of total ground water - ---------- 0.2 California to less than 5 in. in the desert areas. In the Percentage of total livestock - ------------ 41 populated areas of the coastal valleys and southern California, Industrial self-supplied withdrawals: annual precipitation generally ranges from 10 to 20 in. §££^£5?^^: - - - - - ------ -6 (California Department of Water Resources, 1983, p. 8-9). Percentage of total industrial self-supplied: Natural recharge of ground water, from precipitation and Including withdrawals for thermoelectric power - - - - 54 stream infiltration, averages about 5.2 bgd statewide. Ground Excluding withdrawals for thermoelectric power - - - - 89 water also is recharged by an estimated 6.6 bgd of applied Irrigation withdrawals: irrigation water that percolates through the root zone to the S£^5£JCL~waii: ~- '- '- '- '- - ~- '- ~- ^5 water table (California Department of Water Resources, 1983, Percentage of total irrigation 39 p. 88). - California is one of the most physiographically and geologically diverse States in the United States. The terrain is characterized by the massive, rugged glaciated mountains of PRINCIPAL AQUIFERS the Sierra Nevada and Cascade Ranges, the rugged Coast About 40 percent of the land in California is underlain by Ranges with their interspersed valleys, the broad and flat aquifers (California Department of Water Resources, 1975a, Central Valley, and the alternating basins and ranges of the p. 7). These aquifers are composed of alluvium and older desert areas (fig. 1). The mountains are formed of consolidat- sediments, mostly of continental origin, and volcanic rock, ed sedimentary, metamorphic, and igneous rocks. Geologic The sedimentary aquifers underlie the major valleys, coastal structures are complex, with abundant folds and faults, many plains, and desert basins (fig. 1). of which are active. Earthquakes are common, particularly in Alluvial and other sedimentary aquifers in California are the Coast Ranges. The valleys of California are filled with divided into four geographic areas: coastal basins, Central alluvium and other sedimentary materials that comprise most Valley, southern California, and desert areas. A simplified of the principal aquifers. summary of aquifer and well characteristics is given in table 2; 148 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in California [Mgal/d = millions of gallons per day; gal/min = gallons per minute; ft = feet. Sources: Reports of the U.S. Geological Survey and California Department of Water Resources, I975a, 1980] Aquifer name and description Water withdrawals Well characteristics Depth (ft) Yield (gal/min) Remarks in 1980 Common May Common May (Mgal/d) range exceed range exceed Alluvium and older sedimentary aquifers: Coastal basins: Sand, gravel, silt, and clay; continental and marine origin. Unconfined and confined. 1,630 50-500 1,000 500-1,000 Southern California: Sand, gravel, silt, and clay; continental and marine origin. Unconfined and confined. Central Valley: Sand, gravel, silt, and clay; continental and marine origin. Unconfined and confined. Basin-fill, desert areas: Sand, gravel, silt, and clay, mostly of continental origin. Unconfined and confined. 1,720 50-1,000 1,500 500-1,500 10,000 50-500 1,000 50-1,500 700 20-400 1,000 200-1,500 Volcanic rocks: Andesite, rhyolite, and basalt. Mostly unconfined; confined locally. unknown 75-200 300 100-1,000 3,000 Aquifers consist of alluvium and older sediments that fill valleys which are tributary to the Pacific Ocean. Multiple aquifer systems are common. Most intensively developed areas are in Santa Clara, Salinas, and Santa Maria Valleys and Santa Rosa area. 4,000 Productive aquifers in coastal plains and inland valleys of Ventura, Los Angeles, Orange, and San Bernardino Counties. Seawater intrusion, once a problem in coastal areas, now under control. 3,000 Largest aquifer system and greatest concentration of ground-water pumpage in California. Corcoran Clay Member, an extensive confining layer, exists in much of San Joaquin Valley. 4,000 Aquifers in some basins deep, and some wells have large yields. Recharge limited by little rainfall. Some aquifers recharged by runoff from streams that originate in high mountains. 4,000 Water occurs in rubble zones, pipes, and fractures. Well yields extremely variable, with a few exceptionally productive wells and many dry holes. Potential yield far exceeds present use. the areal distribution of the aquifers is shown in figure 1. However, the geology can be locally complex, and multiple- aquifer systems are common. Numerous faults, folds, and uplifts may function as local hydraulic barriers. ALLUVIUM AND OLDER SEDIMENTARY AQUIFERS Aquifers of the coastal basins consist mainly of alluvium and older sediments that underlie the valleys that drain into the Pacific Ocean from the Oregon border to Santa Barbara County. The largest valleys are the Santa Clara, the Salinas, and the Santa Maria Valleys and the Santa Rosa area (valleys tributary to the Russian River). The most intensively deve- loped areas are the Santa Clara and Salinas Valleys. The Central Valley of California (fig. 1) is one of its most intensively developed areas of irrigated agriculture. The Cen- tral Valley is about 500 miles (mi) long and 20 to 50 mi wide, with a total area of about 16,000 square miles. The northern part is known as the Sacramento Valley, whereas the southern part is known as the San Joaquin Valley. The alluvium and older sediments that underlie the Central Valley constitute one of the world's most extensive aquifer systems. Sediments extend to depths of more than 25,000 feet (ft). Freshwater (dissolved solids less than 2,000 mg/L) is present to depths of as much as 4,000 ft (Page, 1973), but most wells are less than 1,000 ft deep. An extensive confining layer known as the Corcoran Clay Member of the Tulare Formation underlies much of the San Joaquin Valley at depths ranging from 200 to 500ft. The principal aquifers of southern California are in the coastal plains of Ventura, Los Angeles, and Orange Counties and in adjacent inland valleys. The productive aquifers consist of alluvium and other continental sediments in the inland National Water Summary California 149 EAST Basin and Range Coast Ranges Coastal Valleys HJ1|L Block faults Corcoron Clay confining layer SOUTHERN CASCADE RANGE -E5S3ffiUi -'} *) s-- » N X NC I - Sea level Alluvium and older sediments- coastal basin H Alluvium and older sediments-- southern California n Alluvium and older sediments-- Central Valley Basin-fill deposits in desert areas Volcanic rocks Not a principal aquifer Figure 1. Principal aquifers in California. A, Geographic distribution. B, Physiographic diagram and divisions. C, Generalized cross section. (See table 2 for a more detailed description of the aquifers. Sources: A, California Department of Water Resources, 1975a, 1980. B, Raisz, 1954. C, Compiled by A. M. Spieker from U.S. Geological Survey files.) 150 National Water Summary Ground-Water Resources areas that interfinger with deltaic and marine sediments in the coastal areas. BASIN-FILL AQUIFERS The desert areas comprise much of southeastern Califor- nia (fig. 1). The topography consists of alternating basins and block-faulted mountain ranges. The basins are typically underlain by basin-fill deposits. The principal aquifers are alluvium, with interbedded lacustrine deposits. Many basins are deep, but well yields are variable. The desert areas are the driest parts of California. Consequently, recharge is not abundant. What does occur is largely from streams, such as the Mojave River, that originate in the higher mountain areas, where rainfall is more abundant. VOLCANIC ROCK AQUIFERS Volcanic rock aquifers are mainly in northern California, on the flanks of the Cascade and Siskiyou Ranges and along the east side of the Sacramento Valley. The most common rock types are andesite, rhyolite, and basalt. Some volcanic rocks are excellent aquifers, but most water is found in fractures, rubble zones, and sand and gravel layers interbed- ded between lava flows. A few wells are extremely productive, but dry holes abound. Except in Butte and Shasta Valleys, which contain areas with numerous production wells, the volcanic rock aquifers are not used extensively. OTHER AQUIFERS Consolidated rock aquifers in the mountains and foot- hills crystalline rock in the Sierra Nevada and bedded sand- stones in the Coast Ranges supply thousands of rural domes- tic wells. A regional carbonate rock aquifer system near Fish Lake and Death and Ivanpah Valleys, that underlies much of eastern and southern Nevada, barely extends into California. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS California had a ground-water withdrawal of 14.6 bgd in 1980, by far the largest of any State (California Department of Water Resources, 1983, p. 88). The location of the major pumping centers and representative hydrographs indicating long-term water-level trends are shown in figure 2. Informa- tion on population served and categories of use is given in table 1. The most striking feature of figure 2 is the concentra- tion of ground-water pumpage in the Central Valley. More than 10 bgd (about 70 percent of the 1980 withdrawals) were from this area (California Department of Water Resources, 1983, p. 111-127). Irrigation accounts for 85 percent of all ground-water withdrawals in California (table 1). Thus, the withdrawals, here stated in million gallons per day over the entire year, actually occur largely during 4 to 5 months generally May through September. Apart from the Central Valley, the greatest concentra- tions of ground-water withdrawals are in southern California and in the Santa Clara and Salinas Valleys. Most cities in the San Joaquin Valley are supplied entirely by ground water, and ground water is a significant part of the public supplies in southern California and the Santa Clara Valley. The six hydrographs in figure 2 show water-level trends in representative areas affected by pumping. Steady water-level declines are observed in areas where imported water is not available, such as Antelope Valley (location 17, fig. 2). Less severe declines have occurred in the Salinas Valley (location 3, fig. 2). Imported water became available to many areas, such as Santa Clara Valley, the Central Valley, and Orange Coun- ty, in the mid- to late 1960's. Hydrographs from Santa Clara Valley, Orange County, and Mendota wells, (location 2, 10, and 18, fig. 2, respectively) show that water levels, which previously had been declining, began to rise at that time. Climatic trends are illustrated by generally declining levels during droughts in the 1930's and the late 1970's. The Fresno and Mendota wells in the Central Valley, which are only about 25 mi apart, show strikingly different trends. Imported water is available in both areas. The Fresno well (location 19, fig. 2) is in an unconfined aquifer and the Mendota well (location 18, fig. 2) is in a confined one. Despite the availability of imported water, overdraft has continued in the Fresno area in response to increased pumping. The hydrograph from the Mendota well shows a water-level recov- ery beginning about 1968 when pumping was reduced as imported water became available. A dramatic decline of the water level during the drought of 1977 and 1978 also is apparent on the hydrograph. GROUND-WATER MANAGEMENT California does not have statewide comprehensive ground-water-management laws. Management is practiced largely by local agencies. The California Department of Water Resources is the State's principal water agency. Its role in ground water is one of providing advice and technical support to local agencies, collecting data, and conducting investigations. The State Water Resources Control Board and nine Regional Boards establish and enforce standards for ground-water quality. The Department of Health Services monitors the quality of drinking-water supplies. The U.S. Geological Survey maintains a cooperative program for data collection and hydrologic investigations with several State and numerous local agencies. Water rights have been adjudicated in eight ground-water basins where conflicts among users have arisen (Peters, 1982). Seven of these basins are in southern California. The Orange County and Santa Clara Valley Water Districts have been granted authority to regulate and tax pumpage and to import water. Several counties have enacted ordinances regulating the export of ground water. One such ordinance, in Inyo County, where the Los Angeles Department of Water and Power is exporting water from Owens Valley, was struck down by the Superior Court of Inyo County, but the appeal was delayed for the duration of a proposed 5-year cooperative study by Inyo County and the city of Los Angeles to develop a water-management plan. The California State Water Resources Control Board has the authority to file an action in the Superior Court to restrict pumping or to impose physical solutions, or both, to the extent necessary to prevent degradation of the quality of ground water. Under the threat of such action concerning seawater intrusion in the Oxnard Plain of Ventura County, the Fox Canyon Water Management District was organized in 1983 to regulate pumping and to obtain water from the Santa Clara River for artificial recharge. Major ground-water issues include ground-water over- draft, seawater intrusion, land subsidence, and artificial re- charge and conjunctive use of ground water (Peters, 1982). The California Department of Water Resources (1980, p. 3) has identified 42 ground-water basins in overdraft, 11 of them in a "critical condition of overdraft," defined as a situation where "***continuation of present water management prac- tices would probably result in significant adverse overdraft- related environmental, social, or economic impacts." Eight of National Water Summary California 151 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) 100-499 500-999 1,000 - 2,499 2,500 - 4,999 5,000 - 7,500 Location number Withdrawal site o '"Hydrograph only 1925 1935 1945 1955 1965 1975 1985 1925 1935 1945 1955 1965 1975 1985 0 20 40 60 80 100 120 140 160 180 - 17 Alluvial aquifer Confined I I I i I I I I I I I 250 300 350 400 450 500 550 600 650 700 - 18 Alluvial aquifer Confined I I I I I I I I I o 20 40 60 80 100 120 140 160 180 Missing record 19 Alluvial aquifer Unconfined I i i i I I I I (925 1935 1845 1955 1965 1975 1985 1925 1935 1945 1955 1965 1975 1985 1925 1935 1945 1955 1965 1975 19B5 WITHDRAWAL SITES [Aquifers are all alluvium and older sediments or basin-fill deposits except for Butte and Honey Lake Valleys, which are volcanic rocks] No. on map 1 2 3 4 5 6 7 8 9 10 Geographic area Butte Valley ......... Santa Clara Valley ..... Salinas Valley ........ Santa Maria River Valley. . Venture County basins. . . Los Angeles Coastal area . . Orange County Coastal Plain. Principal uses Irrigation, domestic, livestock. Public supply, industrial. Irrigation, domestic, live- stock, Industrial. Do. Irrigation, public supply, industrial. Irrigation, public supply. Public supply, domestic, industrial. Public supply, industrial. Do. Irrigation, public supply, industrial. No. on map 11 12 13 14 15 16 17 Geographic area San Bernardino-Riverside area. San Diego County basins. . . Northern San Joaquin Valley. Southern San Joaquin Valley. Honey Lake Valley and Susanville area. Principal uses Irrigation, public supply, industrial. Do. Irrigation, domestic, livestock, industrial. Irrigation, drainage, domestic, industrial, public supply, livestock. Irrigation, domestic, industrial, public supply, livestock. Irrigation, domestic, livestock. Irrigation, public supply. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in California. (Sources: Withdrawal data from California Department of Water Resource, 1983; water-level data from U.S. Geological Survey files.) 152 National Water Summary Ground-Water Resources the 11 basins are in the Central Valley; one each is in Santa Cruz, Santa Barbara, and Ventura Counties. Statewide over- draft in 1980 was estimated at 1.6 bgd (California Department of Water Resources, 1983, p. 88). Seawater intrusion was most intense in the coastal basins of Los Angeles, Orange, and Ventura Counties, the Pajaro and Salinas Valleys, and the Fremont area of Alameda County from 1945 to 1965. It is now under control in most of these areas as a result of management programs that include injec- tion-well barriers, controls on withdrawals, artificial recharge, and imported water (California Department of Water Re- sources, 1975b, 1980). Intensive pumping of aquifers in the San Joaquin and Santa Clara Valleys has caused land subsidence over large areas, as much as 29 ft in the Los Banos-Kettleman City area (Ireland and others, 1984, p. 17). Little subsidence has oc- curred since imported water became available in the late 1960's, except for a slight resumption during the drought of 1977-78. Artificial recharge and conjunctive use of surface and ground water are major elements of ground-water manage- ment in California. Artificial recharge was first used in southern California in the 1920's; it is widely used there now and in the Central and Santa Clara Valleys as well. Imported water is available in all these areas. An interesting variation on artificial recharge is "in-lieu replenishment," whereby imported water is delivered directly to users in return for reduction of ground-water withdrawals by an equivalent amount. SELECTED REFERENCES Bertoldi, G. L., 1979, A Plan to Study the Aquifer System of the Central Valley of California: U.S. Geological Survey Open-File Report 79-1480,48 p. California Department of Water Resources, 1975a, California's ground water: California Department of Water Resources Bulle- tin 118,135 p. __1975b, Sea-water intrusion in California Inventory of coastal ground-water basins: California Department of Water Re- sources Bulletin 63-5, 394 p. __1980, Ground water basins in California A report to the Legis- lature in response to Water Code Section 12924: California Department of Water Resources Bulletin 118-80, 73 p. __1983, The California Water Plan Projected use and available supplies to 2010: California Department of Water Resources Bulletin 160-83, 268 p. Diamond, Jonathan, and Williamson, A. K., 1983, A summary of ground-water pumpage in the Central Valley, California, 1961-77: U.S. Geological Survey Water-Resources Investiga- tions Report 83-4037, 70 p. Ireland, R. L., Poland, J. F., and Riley, F. S., 1984, Land subsidence in the San Joaquin Valley, California, as of 1980: U.S. Geologi- cal Survey Professional Paper 437-1,193 p. Moyle, W. R., Jr., 1974, Geohydrologic map of southern California: U.S. Geological Survey Water-Resources Investigations Report 48-73. Page, R. W., 1973, Base of fresh ground water (approximately 3,000 micromhos) in the San Joaquin Valley, California: U.S. Geolog- ical Survey Hydrologic Investigations Atlas HA-489. Peters, H. J., 1982, Ground water management in California: Ameri- can Society of Civil Engineers, Las Vegas, Nev., April 26-30, 1982, Preprint 82-035, 13 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., and Mann IV, W. B., 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Thomas, H. E., and Phoenix, D. A., 1976, Summary appraisals of the Nation's ground-water resources California Region: U.S. Geological Survey Professional Paper 813-E, p. E1-E51. Prepared by Andrew M. Spieker For further information contact District Chief, U.S. Geological Survey, Room W-2235, Federal Building, 2800 Cottage Way, Sacramento, CA 95825 U.S. Geological Survey Water-Supply Paper 2275 COLORADO Ground-Water Resources National Water Summary Colorado 153 Table 1. Ground-water facts for Colorado [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] Population served by ground water, 1980 Ground water constitutes 18 percent of the total water used in Colorado, and, in some areas, is the main source for domestic and irrigation supply. Fifteen percent of the total population get their drinking-water supply from ground wa- ter. Public supplies provide ground water to 320,000 people, and private wells provide ground water to 125,000 people, mostly in rural areas. Ground-water withdrawals for irrigation X1 , ,t. , , ., nj f , . -iUj i /-*r u i Number (thousands) - ------------------ 445 are 96 percent of total ground-water withdrawals. Of the total Percentage of total population -------------- 15 2.7 million acres irrigated in Colorado, 2.1 million acres are From public water-supply systems: irrigated with ground water 1.6 million acres are irrigated Number (thousands) - ---------------- 320 with a combination of ground water and surface water, and Percentage of total population- ------------ 11 0.5 million acres are irrigated only with ground water. From rural self-supplied systems: *-. j -.LUJ i mo/\ c Number (thousands) ----------------- 125 Ground-water withdrawals in 1980 for various uses are given Percentage of total population- ------------- 4 in table 1, along with related statistics. Freshwater withdrawals, 1980 Surface water and ground water, total (Mgal/d) ----- 16,000 GENERAL SETTING Ground water only (Mgal/d) -------------- 2,800 . , ... _ u * T / u * Percentage of total- ----------------- 18 Annual precipitation ranges from about 7 in. (inches) in Percentage of total excluding withdrawals for the San Luis Valley to about 40 in. in the Rocky Mountains. thermoelectric power ---------- - - - - - . is Eastern Colorado, where most crops are grown, receives less Cateaorv of use than 20 in., so that irrigation is required. Only a small - percentage of rainfall recharges the aquifers; for example, Public-supply withdrawals: annual recharge to the High Plains aquifer in Colorado is only gSSSSSS^otd'wa^: I I I I I I I I I I I - 1 about 0.18 to 1.7 in. Percentage of total public supply- ------------ 8 Geologic and topographic features cause significant dif- Per capita (gal/d) ------------------ 150 ferences in ground-water availability and conditions from one Rural-supply withdrawals: part of the State to another. Major descriptive areas of the Domestic: State, based on geology topography, drainage and physiog- £±£5£3fc^: : '- - - - '- - - '- - - f raphy, are the South Platte River basin, the Arkansas River Percentage of total rural domestic ---------- 36 basin, and the High Plains in eastern Colorado; the Rocky Per capita (gal/d) ----------------- 280 Mountain area in central Colorado; and western Colorado Livestock: (fig. 1). Ground water (Mgal/d)- -------------- 19 Percentage of total ground water- ---------- 0.7 PRIMriPAl AOMIFFRCi Percentage of total livestock - ------------ 18 ri-UNUirAL AUUir-tl-lC5 Industrial self-supplied withdrawals: The most productive and easily developed aquifers in Ground water (Mgal/d)- --------------- 16 Colorado are those in unconsolidated sand and gravel depos- Percentage of total ground water- ----------- 0.6 its. However, where these aquifers are not present, adequate Percentage of total industrial self-supplied: ,. , ul j < -e -A Including withdrawals for thermoelectric power ----- 2 supplies generally can be obtained from aquifers in deeper, Excluding withdrawals for thermoelectric power ----- 1 consolidated rock. Irrigation withdrawals: Colorado has seven principal aquifers or aquifer systems Ground water (Mgal/d)- -------------- 2,700 (fig. 1, table 2). Four of the principal aquifers consist of Percentage of total ground water- ----------- % unconsolidated deposits and include the alluvial aquifer along Percentage of total irrigation ------------- 19 the South Platte River and its tributaries, the alluvial aquifer along the Arkansas River and its tributaries, the High Plains aquifer underlying the High Plains, and the San Luis Valley UNCONSOLIDATED SEDIMENTARY ROCK AQUIFERS aquifer system in the Rocky Mountain area. Most withdraw- als, which in Colorado are primarily for irrigation, are from South Platte Alluvial Aquifer the aquifers in the unconsolidated deposits. The remaining The South Platte alluvial aquifer is an extensive system three principal aquifers consist of consolidated rock and consisting of unconsolidated sand and gravel and minor beds include the Denver Basin aquifer system in the South Platte of clay and silt that were deposited in broad valleys eroded River basin and part of the Arkansas River basin, the Piceance into underlying consolidated sedimentary rock. This uncon- basin aquifer system in western Colorado, and the Leadville fined aquifer is in hydraulic connnection with the South Platte limestone aquifer in the Rocky Mountain area. Also shown in River along its mainstem and major perennial tributaries, figure 1 are several other aquifers (including the Dakota, Other tributaries flow only in response to intense thunder- Morrison, and Entrada aquifers in southwestern Colorado) storms or rapid snowmelt. The principal use of water is for that are not principal aquifers, in Colorado, but are included irrigation, although some water is used for public supply, because of their significance in adjacent States. The aquifers Significant ground-water development began in 1934 (Hvr in Colorado are described below and in table 2, from youngest and others, 1975), and by 1980 more than 7,500 wells tapped to oldest; their areal distribution is shown in figure 1. the aquifer for irrigation. 154 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Colorado [Ft = feet; gal/min = gallons per minute; ft /d = feet squared per day; mg/L = milligrams per liter; ft /s = cubic feet per second. Sources: Reports of the U.S. Geological Survey, Colorado Water Conservation Board, and Colorado Geological Survey] Well characteristics Aquifer name and description Depth (ft) Common May range exceed Yield (gal/min) Common May range exceed Remarks Principal Aquifers Unconsolidated sedimentary rock aquifers: South Platte alluvial aquifer: Interbedded gravel, sand, silt, and clay; contains some cobbles and boulders; unconsolidated. Generally unconfined. Arkansas alluvial aquifer: Boulders, cobbles, gravel, sand, and clay. Generally grades from fine sand near the surface to coarse sand and gravel at the base. Generally unconfined. High Plains aquifer: Gravel, sand, silt, and clay; contains some caliche. Poorly to moderately consolidated. Generally unconfined. San Luis Valley aquifer system: Unconfined aquifer: Clay, silt, sand, and gravel; unconsolidated. Alluvial and lacustrine. 0 to 200 ft thick. Confined aquifer: Clay, silt, sand, and gravel, unconsolidated, interbedded with lava flows and tuffs. As much as 19,000 ft thick. Consolidated sedimentary rock aquifers: Denver Basin aquifer system: Dawson aquifer: sandstone and conglomerate with interbedded shale, siltstone. Confined except near outcrop Denver aquifer: Sandstone with interbedded shale, siltstone, and coal. Confined except near outcrop area. Arapahoe aquifer: Sandstone and conglomerate with interbedded shale, siltstone. Confined except near outcrop area. 30-150 250 100-1,500 3,000 25 - 100 200 100-1,200 1,500 200-400 450 350-2,000 2,500 50-150 150 500-1,200 2,000 300-800 2,000 500-1,200 2,000 200-1,000 1,400 5-150 300 200-1,500 2,100 200-2,000 2,600 5-100 10-600 300 800 Provides water for public supplies and supplemental irrigation. Transmissivity ranges from 2,000 to 200,000 ft2/d. Dissolved-solids concentration ranges from 100 mg/L in areas overlain by dune sand to about 4,000 mg/L in some downstream areas. Water hard to extremely hard. Local areas show significant water-level declines. Principal source of water for irrigation, public supply, and industrial wells. Transmissivity ranges from 1,000 to 150,000 ft /d. Dissolved-solids concentration ranges from about 800 to 5,000 mg/L. Water hard to extremely hard. Primary source for irrigation, public supply, and domestic use. Transmissivity ranges from 3,000 to 30,000 ft /d. Dissolved-solids concentration generally ranges from 200 to 500 mg/L. Widespread water-level declines affecting well production and increasing irrigation costs. Provides supplemental irrigation water. Withdrawals greatest in Rio Grande and western Alamosa Counties. Transmissivity ranges from 100 to 34,000 ft /d. Dissolved-solids concentration ranges from 72 to 31,200 mg/L. Local areas show water-level declines. Provides supplemental irrigation water. Withdrawals greatest in Conejos and western Saguache Counties. Transmissivity ranges from 200 to 200,000 ftvd. Dissolved-solids concentration ranges from 60 to 2,440 mg/L. Sandstone thickness ranges from 100 to 400 ft. Dawson is uppermost aquifer in group. Primarily used for rural and public supply. Potential for local contamination from Lowry landfill in Arapahoe County. Less than 200 mg/L dissolved solids. Sandstone thickness ranges from 100 to 300 ft. Denver contains more shale than other aquifers in group. Used primarily for domestic supply. Generally less than 200 mg/L dissolved solids. Sandstone thickness ranges from 100 to 350 ft. Arapahoe most permeable aquifer in group. Used extensively for public, commercial, and domestic supply. Less than 500 mg/L dissolved solids. National Water Summary Colorado 155 L» ms" - > f , , QVJ^J*fS«JN ->-- A / }.' O- - - fRE EXPLANATION UNCONSOLI DATED SEDIMENTARY ROCK AQUIFERS | ] South Platte alluvial ^^1 Arkansas alluvial [ | High Plains San Luis Valley aquifer system CONSOLIDATED SEDIMENTARY ROCK AQUIFERS \ K Denver Basin aquifer system ^^1 Piceance Basin aquifer system Leadvilie limestone OTHER AQUIFERS I Dakota, Morrison and Entrada Not a principal aquifer A A' Trace of cross section A WEST Meeker Continental Divide Colorado R Boulder cou th Platte R HIGH PLAINS EAST PICEANCE BASIN WHITE RIVER UPLIFT DENVER BASIN HIGH PLAINS Figure 1. Principal aquifers in Colorado. A, Geographic distributions. B, Physiographic diagram and divisions. C, Generalized cross section (A-A'). (See table 2 for more detailed description of the aquifers. Source: A, C, Compiled by R. T. Hurr from U.S. Geological Survey files. B, Fenneman, 1931; Raisz, 1954.) 156 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Colorado Continued Well characteristics Aquifer name and description Depth (ft) Common May range exceed Yield (gal/min) Common May range exceed Remarks Principal Aquifers Continued Laramie-Fox Hills aquifer: Sandstone and conglomerate with interbedded shale, siltstone, and coal. Confined except near outcrop areas. Piceance basin aquifer system: Upper aquifer: Coarse-to fine-grained silty sandstone and siltstone of the Uinta Formation and fractured dolomite marlstone of the Parachute Creek Member of the Green River Formation above the Mahogany zone. Generally confined. Lower aquifer: Fractured dolomitic marlstone of the Parachute Creek Member of the Green River Formation below the Mahogany zone. Generally confined. Leadville limestone aquifer: Gray dolomitic limestone with some sandstone and chert. Confined. 200-2,500 3,200 2 - 300 400 Sandstone thickness ranges from 100 to 200 ft. Laramie-Fox Hills is deepest aquifer in group. Permeability small along western margin of basin. Potential for local contamination from the Marshall landfill in Boulder County. About 500 to 2,000 mg/L of dissolved solids. 500-1,000 1,400 10-500 2,000 Potential of aquifer not developed. Water almost exclusively in fractures. Transmissivity ranges from 10 to 600 ftVd. Dissolved- solids concentration generally ranges from 400 to 2,000 mg/L. 600-2,000 2,800 2-50 100 2,000 Potential of aquifer not developed. Transmissivity ranges from 10 to 600ft /d. Water commonly contains dissolved gas. Dissolved-solids concentration ranges from about 500 to 40,000 mg/L. 500 Potential of aquifer not developed. Some exploratory wells drilled in Eagle County. Spring on Rifle Creek, north of Rifle, Colorado, discharges 11 ft /s. Other Aquifers Western Colorado alluvial aquifers: Boulders, cobbles, gravel, sand, silt, and clay; unconsolidated and only moderately sorted. Generally unconfined. San Juan basin aquifers: San Jose aquifer: Alternating sandstones commonly are conglomerate, rich in feldspar. Confined. Animas aquifer: Sandstone and varicolored shale with interbedded breccia and volcanic conglomerate. Confined. Mesaverde Group aquifer: Marine sandstone with interbedded siltstone and shale; coal-bearing in middle part of group. Confined, except near outcrop areas. 20-40 140 5-100 500 50-300 1,400 5-1,000 1,500 50-200 300 1-15 800 1,000-1,500 5,000 1-10 500 Alluvial aquifers along Yampa, White, Colorado, and Uncompahgre Rivers provide some water for irrigation, public supply, and industrial use. Capability of aquifer in terms of yield and quality not determined. Measured transmjssivity values as muchas75,OOOftVd. In southern part of western Colorado, principally in La Plata County and western part of Archuleta County. Potential of aquifer not developed in Colorado. Hydraulic conductivity of fractured shale ranges from 0.2 to 0.3 ft/d. Dissolved-solids concentration ranges from 300 to 450 mg/L. In western Colorado (Routt, Moffat, Montezuma, La Plata, and Archuleta counties). Water ranges from sodium bicarbonate type to calcium sulfate type, depending on presence or absence of shales. Dissolved-solids concentration ranges from 180 to 1,200 mg/L. May contain dissolved iron in excess of national drinking-water regulations. National Water Summary Colorado 157 Table 2. Aquifer and well characteristics in Colorado Continued Well characteristics Aquifer name and description Depth (ft) Yield (gal/min) Remarks Common range May exceed Common range May exceed Other Aquifers Continued Mancos Shale unit: Silty and sandy marine shale; contains some interbedded sandstones and limestones. Unconfined. Dakota aquifer: Sandstone with interbedded siltstone and carbonaceous shale; contains many conglomerate lenses near base. Confined. Morrison aquifer: Fine- to medium-grained, thin-bedded sandstone, and varicolored red and green shale. Entrada aquifer: Medium- to very fine grained sandstone with some silt and clay. Confined. Precambrian crystalline unit: Quartz-biotite gneiss and. schist with some hornblende gueiss and quartzite; intruded by granite and quartz monzonite batholiths and other intrusives. Unconfined. 200-1,000 2,000 1-25 500 20-50 200 1 - 10 25 In Pitkin County and throughout western Colorado. Commonly used for stock and domestic water where other aquifers are too deep or have poorer quality water. Water generally contained in fractures or weathered zones. Water is predominantly sodium bicarbonate type. Dissolved-solids concentration ranges from 200 to 4,800 mg/L. Includes the Cheyenne Sandstone in the Arkansas River basin; also in southern one-half of western Colo- rado. Many wells flow at surface. Wa- ter ranges from sodium bicarbonate to calcium bicarbonate type. Dissolved- solids concentration ranges from 300 to 3,500 mg/L. 15 In the southern one-half of western Colorado. Water is calcium bicarbonate type. Dissolved-solids concentration ranges from 200 to 300 mg/L. 35 In the southern one-half of western Colorado. Water generally sodium bicarbonate type. Some water contains dissolved hydrogen sulfide gas. Average value for transmissivity in Grand Junction area 20 ft2/d. 15 In the Rocky Mountain area. Used extensively along the Front Range between Fort Collins and Colorado Springs. Water available only from fractures. Transmissivity typically less than 10 ft2/d. Dissolved- solids concentration ranges from 20 to 1,600 mg/L. 250-600 1,000 1-10 500-700 1,200 1-25 100 - 250 350 0.5 - 5 Recharge to the aquifer occurs mostly as leakage from reservoirs and ditches and as deep percolation of applied irrigation water diverted from the South Platte River and its major tributaries. Since about 1863, the recharge has in- creased water levels to the extent that ground water discharges to streams, augmenting their flow and providing more water for diversion downstream. Withdrawals by wells have re- duced the flow of ground water to some streams (Hurr and others, 1975). Arkansas Alluvial Aquifer The Arkansas alluvial aquifer is similar to, but not as extensive as, the South Platte alluvial aquifer. In many areas, clay or sandy clay in the upper part of the alluvium confines the aquifer. Otherwise, the aquifer generally is unconfined. In general, the aquifer is in hydraulic connection with the Arkansas River and its major tributaries. The principal use of water is for irrigation, although some water is used for public supply and powerplant cooling. Significant development be- gan about 1950 (Major and others, 1970), and, by 1980, about 2,900 wells tapped the aquifer for irrigation. As in the South Platte River basin, recharge is mostly from leakage and percolation of water diverted from streams, but the rate of recharge is less. In general, the ground water moves toward and discharges to the principal streams. With- drawals by wells have reduced the flow of ground water to some streams and, in a few areas, have induced flow from the streams to the aquifer. High Plains Aquifer The High Plains area is underlain by the High Plains aquifer, which consists principally of the Ogallala Formation but includes overlying alluvium and dune Sand and the under- lying Arikaree Formation and White River Group. The Ogal- lala Formation is comprised of unconsolidated to partly consolidated sand and gravel with minor beds of clay and silt and a hard caliche layer, known as the "mortar beds," several feet thick near the top. The formation dips gently eastward. 158 National Water Summary Ground-Water Resources Although the aquifer generally is unconfined, wells completed in less than the full saturated thickness may respond to leaky artesian conditions because lenses and layers of silt and clay function as semipermeable, leaky confining beds. Although the principal use of ground water is for irrigation (Luckey and others, 1981), ground water also is used to meet public supply and nearly all stock and rural domestic water needs. By 1980, the High Plains aquifer was tapped by approximately 4,100 irrigation wells, 83 municipal wells, and 3,990 wells for stock and domestic use. Inasmuch as the only source of recharge to the High Plain aquifer is precipitation, which averages from 14 to 18 in. per year, these wells are withdrawing water from storage and, consequently, reducing ground-water flow into Kansas and Nebraska. San Luis Valley Aquifer System The San Luis Valley aquifer system is comprised of several thousand feet of sand and gravel that contain lava flows and lenses and layers of clay and silt (Emery and others, 1975). The system is subdivided into confined and unconfined aquifers. The shallow aquifer generally is unconfined and in hydraulic connection with the Rio Grande and the Conejos River. Deeper aquifers within the system are confined by clay layers or lava flows. The principal use of the ground water is for irrigation, although some is used to meet public supply, rural domestic, and stock needs. Also, some deep wells provide hot water that is used for heating. In 1887, when the discovery was made that flowing water could be obtained from the artesian aquifer system, numerous wells were drilled for stock and domestic use and allowed to flow freely. In the early 1950's, withdrawal of ground water for irrigation had become significant, and by 1980, approximately 3,720 irriga- tion wells had been drilled in the San Luis Valley. Recharge to the San Luis Valley aquifer system is by leakage from canals and ditches, percolation of applied sur- face water, and subsurface flow from adjacent mountains. The ground water moves from the margins of the valley toward the interior and discharges as evapotranspiration or to springs and streams. As a result of the large ground-water withdrawals, water levels have declined and evapotranspira- tion and discharge to springs and streams have been reduced. CONSOLIDATED SEDIMENTARY ROCK AQUIFERS Denver Basin Aquifer System The Denver Basin aquifer system, which consists of the Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers, is recharged in its outcrop areas by rainfall, snowmelt, and, in topographically high areas, loss of streamflow. In areas where the Denver aquifer is covered by the Dawson aquifer or the Arapahoe aquifer is covered by the Denver aquifer, the underlying aquifer also may be recharged by downward leak- age from the overlying aquifer. In general, the thick sequence of shale that overlies the Laramie-Fox Hills aquifer prevents significant vertical movement to or from this aquifer. Dis- charge from the aquifers is through wells, by seeps and springs in low areas around the perimeter of the aquifers, as discharge to streams, or by evapotranspiration. The principal use of water from the Denver Basin aquifers is for public supply and individual domestic use. Some ground water also is with- drawn for commercial and industrial use. The total annual production for all uses is about 30 Mgal/d (million gallons per day)(Robson, 1984). Piceance Basin Aquifer System The Piceance basin aquifer system consists of an upper, generally confined aquifer in the Uinta Formation and the upper part of the Green River Formation, and a lower, generally confined aquifer in the middle and lower parts of the Green River Formation. The aquifers are separated by the petroleum-bearing Mahogany zone (Weeks and others, 1974). The Green River Formation, of primary interest for oil-shale development, has little interstitial porosity, so that ground- water flow and well yields are controlled by fracture permea- bility. Wells yielding several hundred gallons per minute have been drilled and tested as part of the program to develop the oil-shale resources, but use of the ground-water resources in the basin has been extremely limited. Leadville Limestone Aquifer The Leadville limestone aquifer crops out in the west- central part of the Rocky Mountain area and underlies much of the northern part of western Colorado. However, it is generally shallow enough to be considered a principal aquifer only in the Rocky Mountain area. Recharge to the aquifer generally is in the higher outcrop areas, and discharge com- monly is by springs along fracture zones and in lower outcrop areas. At present, ground-water withdrawals are small, but the potential of the aquifer to serve as a dependable source of water as indicated by a few exploratory wells (Hampton, 1974) and discharge from numerous springs is significant. OTHER AQUIFERS In the Arkansas River basin (fig. 1), the Dakota aqui- fer principally the sandstones in the Dakota Formation and Cheyenne Sandstone provides water for some public sup- plies and for domestic use. Some wells also have been used to provide ground water for irrigation. The Rocky Mountain area consists primarily of exposed Precambrian igneous and metamorphic rocks, Tertiary vol- canic rocks, and folded and faulted sedimentary rocks. Nu- merous domestic wells obtain water from the fractured igne- ous and metamorphic rocks in the Precambrian crystalline unit. These rocks are the principal source of water for people living in the mountains west of Denver and other areas along the Front Range. Western Colorado contains diverse geologic and hy- drologic conditions. Alluvial aquifers along the major rivers have the potential for supplying water to wells in moderate quantities. Throughout much of western Colorado, the Mesa- verde Group aquifer supplies water to domestic wells. Development of coal resources in the Mesaverde Group may have significant impact on these water resources. In the central and southern parts of western Colorado, domestic water supplies have been obtained from fractures in the weathered part of the Mancos Shale unit. The Dakota, the Morrison, and the Entrada Formations contain sandstone aquifers that supply water to domestic wells and a few public- supply wells. These sandstone aquifers are considered princi- pal aquifers in New Mexico and Utah. The extreme southern part of the area, the San Juan Basin, which extends southward into New Mexico, contains several aquifers, principally the San Jose and Animas that supply water to domestic wells. In many areas of the State, wells tap other aquifers, including sandstones in lower consolidated sedimentary rocks and in volcanic rocks. These aquifers, however, do not pro- vide a significant volume of water compared to the total volume used. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Water-supply systems that produce from 0.1 to 1 Mgal/d are distributed throughout the State. Withdrawals of more National Water Summary Colorado 159 O V § 20 g 40 3 60 3 80 ^ 120 jwT DEPTH TO WATEf _ OB <J> * > 000 ~ 18 South Platte alluvial Unconfined aquifer - ~^~^-^v/V - *\^-^ I I I I I I I I I 35 1945 1955 1965 1975 198 S 1 9 TEH LEVEL, BELOW LAI 38 s< i DU 60 40 20 0 20 40 60 80 too ~ 19 South Platte alluvial Unconfined aquifer - i~ ^ - - - I I I I I I I I I 19 80 60 40 20 0 20 40 60 80 too 19 35 1945 1955 1965 1975 1985 - 20 Arkansas alluvial Unconfined aquifer - - - - I I I | | i i I I 60 40 20 0 20 40 60 80 100 - 21 San Lute Valley Unconfined aquifer system - Missing record - i i I I i I I I I 35 1945 1955 1965 1975 1985 1935 1945 1955 1965 1975 19£ EXPLANATION Ground-water withdrawals, 1980 (milBon gallons per day) O 1.0-5 O 5.1 - 10 © 10.1 - 50 CD 300 -400 - 1100 Location number .5 Ow Withdrawal table 18 o "Hydrograph only WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Geographic area South Platte River Valley. Arkansas River Valley. Widefield. ....... Lamar Light and Power. Eastern Colorado . . . South Central Colorado. East Central Colorado. Aquifer South Platte alluvial ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ Arkansas alluvial ... -do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ San Luis Valley . . . ... .do ........ Principal uses Irrigation. Public supply. Do. Do. Do. Do. Irrigation. Public supply. Do. Do. Do. Power plant, cooling. Public su ->ply. Irrigation. Do. Public supply. Public supply, irrigation, industrial. V LAND SURFAC en *. M c o o O c 1 '80 200 UJ "-_ 220 1 a40 o 26° x 280 fc ~ 22 High Plains aquifer Unconfined ^ ^^^^x^^ - 1 1 1 1 1 1 1 1 1 1935 1955 1965 1975 1985 i eu 200 220 240 280 300 320 360 ~ 23 Denver Basin \ i . aquifer V\ f\ Ul \ Confined ^ \ Missing^ \ record \ A - _ 1 I I I i I 1935 1945 1955 1965 \ 1 i I 1 1975 19t Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Colorado. (Sources: Withdrawal and water-level data from U.S. Geological Survey files.) 160 National Water Summary Ground-Water Resources than 1 Mgal/d are associated only with the principal uncon- solidated aquifers and the Denver Basin aquifer system. The hydrographs shown in figure 2 reflect typical responses to ground-water withdrawals. Water levels in alluvial aquifers show seasonal fluctuations, but show no significant long-term changes in areas where surface water and ground water are used conjunctively for irrigation such as the South Platte River valley (location 19, fig. 2) and the Arkansas River valley (location 20, fig. 2). However, in areas where surface water is not used for irrigation, some long-term water-level declines have occurred. In the High Plains aquifer, ground water is being mined, as indicated by the large decline of ground water shown near location 22 (fig. 2). In the Denver basin (location 23, fig. 2) much of the water-level decline is from loss of artesian head rather than dewatering of the aquifer. GROUND-WATER MANAGEMENT Colorado water law for surface-water diversion is based on the right of prior appropriation. Before 1965, ground- water use was barely regulated, if at all, although well permits were required by the Colorado Division of Water Resources, Office of the State Engineer. In 1965 and 1969, the Ground Water Management Act (C.R.S. 37-90-101 to 104), common- ly referred to as H.B. 1066, and the Water Rights Determina- tion and Administration Act of 1969 (C.R.S. 37-92-101 to 602) were enacted. The latter Act controlled well drilling more effectively and, particularly, the effect that pumping ground water would be allowed to have on surface water hydraulically connected to the aquifer. Ground water that is part of a stream-aquifer system is classified as tributary ground water. Withdrawals of this class of ground water are administered within the priority system by the State Engineer to minimize the effect of withdrawals on surface-water supplies. Water in some aquifers, principally the High Plains aquifer and alluvial aquifers along intermittent or seasonal tributaries to the South Platte and Arkansas Rivers, is considered "designated ground water" and, as such, is controlled by the Colorado Ground Water Commission and local management districts. Water in consolidated "bedrock" aquifers underlying a management district also is managed by the district. Outside of the desig- nated basins and in areas where ground water is considered not tributary to surface water, the ground water is classified as nontributary ground water and is administered by the State Engineer. In these areas, ground water cannot be withdrawn at an annual rate of greater than 1 percent of the volume of water stored beneath the property boundaries of the well owner. Much of the water in the Denver Basin aquifers is classified as nontributary. SELECTED REFERENCES Emery, P. A., Patten, E. P., Jr., and Moore, J. E., 1975, Analog model study of the hydrology of the San Luis Valley, south- central Colorado: Denver, Colorado Water Conservation Board Ground-Water Circular 29, 21 p. Fenneman, N. M., 1931, Physiography of Western United States: New York, McGraw-Hill Book Co., 534 p. Hampton, E. R., 1974, Preliminary evaluation of ground water in the pre-Pennsylvanian carbonate rocks, McCoy area, Colorado: U.S. Geological Survey Open-File Report, lip. Hurr, R. T., Schneider, P. A., Jr., and Minges, D. R., 1975, Hydrology of the South Platte River Valley, northeastern Colorado: Denver, Colorado Water Conservation Board, Colorado Water Resources Circular 28,24 p. Luckey, R. R., Gutentag, E. D., and Weeks, J. B., 1981, Water-level and saturated-thickness changes, predevelopment to 1980, in the High Plains aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: U.S. Geological Survey Hydrologic Investigations Atlas HA- 652. Major, T. J., Hurr, R. T., and Moore, J. E., 1970, Hydrogeologic data for the lower Arkansas River Valley, Denver, Colorado: Denver, Colorado Water Conservation Board Basic-Data Re- lease 21, 125 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C..U.S. Geological Survey, 417 p. Robson, S. G., 1984, Bedrock aquifers in the Denver Basin, Colora- do A quantitative water-resources appraisal: U.S. Geological Survey Open-File Report 84-431, 111 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. U.S. Bureau of the Census, 1982, Census of the population, charac- teristics of the population, number of inhabitants 1980: Wash- ington, D.C., published separately by States, Puerto Rico, and outlying areas, PC 80-1-A1 to A57a, and A57b. Weeks, J. B., Leavesley, G. H., Welder, F. A., and Saulnier, G. J., Jr., 1974, Simulated effects of oil-shale development on the hydrology of Piceance basin, Colorado: U.S. Geological Survey Professional Paper 908, 84 p. Prepared by R. Theodore Hurr and Glenn A. Hearne For further information contact District Chief, U.S. Geological Survey, Building 53, Denver Federal Center, Mail Stop 415, Box 25046, Lakewood, CO 80225. U.S. Geological Survey Water-Supply Paper 2275 CONNECTICUT Ground-Water Resources National Water Summary Connecticut 161 Table 1. Ground-water facts for Connecticut [Withdrawal data rounded to two significant figures and may not add to totals because of independent founding. Mgal/d = million gallons per day; gal/d = gallons per day] Population served by ground water, 1980 1 Ground water is a valuable natural resource that presently supplies about one-third of Connecticut's approximately 3.1 million people. It is becoming an increasingly important resource because of several factors: land for additional surface reservoirs is scarce, cost of developing and operating surface- water sources are large, and State policy favors development KT , ,.. , , no/1 ,, -c f f + ,- , ,no« j -j Number (thousands) - ------------------ 984 of aquifers for future supplies. In 1980, ground water provid- Percentage of total population -------------- 32 ed 17 percent of the total public supply and almost all From public water-supply systems: self-supplied domestic, commercial, and industrial uses. Number (thousands) ----------------- 440 Withdrawals for public supply ranged from 1.8 million gallons Percentage of total population - ------------ 14 per day (Mgal/d) in Tolland County to 20.1 Mgal/d in From rural self-supplied systems: TT *< j V> sr, i j <n i ino-ix A jj- i Number (thousands) ----------------- 544 Hartford County (Pnsloe and Sternberg, 1983). Additional Percentage of total population- ------------ 18 information on ground-water uses is given in table 1. The ~ r rrr , I7ZZ2 quality of the ground water generally is good to excellent and __________Freshwater withdrawals, 1980_________ is suitable for most uses. However, principal aquifers are Surface water and ground water, total (Mgal/d) ------ 1,300 susceptible to contamination because of their shallow depth Gr0l^^^r ^nS^^ --------------- ^0 and thin or very permeable overburden, and numerous local- Percentage of total excluding withdrawals for """"" ized instances of ground-water contamination have been thermoelectric power ---------------- 20 reported - Category of use GENERAL SETTING Public-supply withdrawals3 : Geology and physiography are largely responsible for g£££l£52JCLl""«^ ! I I I I I I I I I I £ differences in ground-water conditions within the State. Sub- Percentage of total public supply - ----------- 17 divisions of the New England physiographic province (Fenne- Per capita (gal/d) ------------------ 148 man, 1938) in Connecticut are shown in figure 1; they include Rural-supply withdrawals: the New England Upland, the Seaboard Lowland, the Tacon- Domestic: ic and the Connecticut Valley Lowland. The firs, three £±^22&^ : : : : : ' ' ' ' ' ' 36 subdivisions have moderate relief and are underlain by crystal- Percentage of total rural domestic ---------- 100 line rocks that have been extensively folded and faulted. The Per capita (gal/d) ----------------- 97 Connecticut Valley Lowland is underlain by a sequence of Livestock: interbedded sedimentary and igneous rocks that may be as Ground water (Mgal/d) - -------------- 0.4 thick as 16,500 feet (ft) (W. J. Wenk, University of Connec- Percentage of total ground water- ---------- 03 . . . v ' , no .. x ~, i / u Percentage of total livestock - ------------ 18 ticut, written commun., 1984). These rock units dip to the east industria, self-supplied withdrawals: and are faulted extensively. Relief generally is low except Ground water (Mgal/d)- --------------- 27 where erosion-resistant igneous rocks form a series of north- Percentage of total ground water - ----------- 18 trending ridges. Unconsolidated glacial sediments of differing Percentage of total industrial self-supplied: thickness discontinuously mantle the bedrock throughout the Including withdrawals for thermoelectric power ----- 3 Oi , , . , , « i Excluding withdrawals for thermoelectric power - - - - 10 State and are most common in the northern part of the irrigation withdrawals- Connecticut Valley Lowland. Ground water (Mgal/d)- --------------- 1.6 Ground-water recharge in Connecticut is mainly from Percentage of total ground water- ------------ i precipitation that percolates from the land surface to the water Percentage of total irrigation -------------- 8 table. Although recharge rates are variable, the long-term , average ranges from about 7 to 20 inches annually. Recharge 2 Dala from Sternberg- l983 - from precipitation occurs mainly during the nongrowing I3ata from Solley. Chase, and Mann, 1983; values for total freshwater r r ,* * T withdrawals, fresh ground-water withdrawals and public supply withdrawals season from fall to late spring. Locally, pumping centers near adjusted based on data from Sternberg, 1983. streams or lakes induce significant additional recharge from 3 [ndudes a,, community water supplies that serve at least lvvo residences or these surface-water bodies. Ground-water flow is concentrat- 25 residents, ed in the upper part of the saturated zone (generally within 300 ft of land surface). Because of the relatively shallow depth of the flow system and moderate topographic relief, ground- provides an estimated 30 percent or more of mean streamflow water circulation in most parts of Connecticut is localized (Mazzaferro and others, 1979, p. 45) and all flow during within each basin drained by a perennial stream. Larger periods where no surface runoff occurs, regional flow systems may be present in the sedimentary rocks of the Connecticut Valley Lowland (Weiss and others, 1982, PRINCIPAL AQUIFERS p. 26). Most ground-water discharge is to nearby streams, Two principal types of aquifers underlie Connecticut- lakes and estuaries, although some ground water is evapotran- unconsolidated stratified-drift aquifers composed of sand and spired or withdrawn by wells. In streams where flows have not gravel and bedrock aquifers composed of sedimentary, igne- been altered by human activities, ground-water discharge ous, and metamorphic rocks. Stratified-drift aquifers overlie 162 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Connecticut [Gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Reports of the U.S. Geological Survey and Connecticut Department of Environmental Protection] Well characteristics Aquifer name and description Depth (ft) Yield (gal/min) Remarks Common range May exceed Common range May exceed Stratified-drift aquifers: Sand and 50-100 150 50-500 2,000 gravel, commonly with interbedded layers or lenses of silt and clay. Generally unconfined. Sedimentary-aquifer system: Sand- 100-300 500 2-50 500 stone, shale, siltstone, and conglo- merate; some interbedded basalt flows and dikes. Unconfined to partly confined in upper 200 ft, may be confined at depth. Crystalline bedrock aquifer 100-300 500 1-25 200 (noncarbonate rocks): Gneiss and schist with minor amounts of other metamorphic and igneous rock types. Generally unconfined in upper 200 ft, may be confined at depth. Carbonate rock aquifer: Marble; 100-300 500 1 - 50 200 some schist and quartzite zones. Generally unconfined in upper 200 ft, may be confined at depth. Largest yields from wells near major rivers. Iron and manganese concentrations commonly exceed 0.3 and 0.05 mg/L, respectively. Dissolved-solids concentrations range from 31 to 1,270 mg/L. Salty ground water present locally in coastal areas. Aquifers susceptible to contamination. Hydrologic characteristics poorly defined, particularly in zones deeper than 300 ft. Generally overlain by variable thicknesses of unconsolidated deposits. Moderately hard to hard water, and large concentrations of dissolved chloride sodium, and sulfate occur locally. Hydrologic characteristics poorly defined, particularly in zones deeper than 300 ft. Generally overlain by variable thicknesses of unconsolidated deposits. Iron and manganese concentrations may exceed 0.3 and 0.05 mg/L, respectively. Dissolved-solids concentrations range from 20 to 1,590 mg/L. Hydrologic characteristics poorly defined, particularly in zones deeper than 300 ft. Generally overlain by variable thicknesses of unconsolidated deposits. Generally hard to very hard water; large iron and manganese concentrations are local problems. the bedrock and store and transmit water through intercon- nected pore spaces. Bedrock aquifers store and transmit water primarily through fracture networks. The characteristics of the stratified-drift and bedrock aquifers are described below and in table 2, from youngest to oldest; their areal distribution is shown in figure 1. STRATIFIED-DRIFT AQUIFERS Stratified-drift aquifers are the most productive sources of ground water in the State. They were formed during the deglaciation of southern New England when interbedded layers of sand, gravel, silt, and clay were deposited in river valleys or in temporary glacial lakes. Stratified-drift aquifers are not distributed evenly (fig. 1) and differ significantly in their ability to yield water. They are most common in the Quinebaug River basin in eastern Connecticut and in the Farmington, the Quinnipiac and the upper Connecticut River basins in the Connecticut Valley Lowland. Because of gener- ally low topographic relief and the history of deglaciation in this area, stratified-drift aquifers are widespread and com- monly extend across surface-water drainage divides in the Connecticut Valley Lowland. Elsewhere in the State, these aquifers generally are less widespread and are confined to valleys. Several stratified-drift aquifers may be present in a single valley, and development of aquifers upstream can affect the yield of aquifers downstream by reducing the amount of streamflow available for induced recharge. Factors that effect well yields include thickness, extent, and permeability of aquifer materials and proximity and flow of adjacent streams that are sources of induced recharge. Where conditions are favorable, well fields can produce several million gallons of water per day. Ground water in stratified-drift aquifers generally is of good to excellent quality, suitable for human consumption and most industrial uses. Constituents that may be present in concentrations excessive for some uses include iron [as much as 40 milligrams per liter (mg/L)], manganese (as much as 5.9 mg/L), silica (as much as 30 mg/L), sulfate (as much as 292 mg/L), and sodium (as much as 314 mg/L). Hard to very hard water (greater than 120 mg/L as calcium carbonate) is common in western Connecticut (Cervione and others, 1972; Ryder and others, 1970) because of dissolution of marble fragments in the stratified drift. Stratified-drift aquifers are susceptible to contamination, and water quality has been affected locally in almost all regions of the State (Rolston and others, 1979). Where stratified-drift aquifers are adjacent to saltwater bodies, exces- sive pumping and coastal flooding have caused saltwater contamination. Major sources of ground-water contamina- tion, which include waste-disposal facilities, accidental spills, 72°30' National Water Summary Connecticut 72° 163 42 41°30 Till -- minor aquifer that forms a fairly continuous cover over bedrock units Sedimentary-aquifer system - Includes interbedded sedimentary and volcanic rocks (basalt) Crystalline-bedrock aquifer (noncarbonate rocks) Carbonate-rock aquifer Water table B A. TACONIC SECTION B. CONNECTICUT VALLEY LOWLAND C. NEW ENGLAND UPLAND SECTION D. SEABOARD LOWLAND SECTION Figure 1. Principal aquifers in Connecticut. A, Geographic distribution. B, Physiographic diagram and divisions. C, Typical relationship between stratif ied-drift and bedrock aquifers. (See table 2 for a more detailed description of the aquifers. Sources: A, Meade, 1978. B, Fenneman, 1938; Raisz, 1954. C, Compiled by R. L Melvin from U.S. Geological Survey files.) 164 National Water Summary Ground-Water Resources chemical storage, and pesticide and fertilizer application, are summarized in Handman and others (1979). SEDIMENTARY, CRYSTALLINE BEDROCK, AND CARBONATE ROCK AQUIFERS Bedrock aquifers underlie the entire State and are the principal source of water for self-supplied homes and small public-supply systems, commercial establishments, and indus- tries. The bedrock aquifers can be subdivided broadly into a sedimentary-aquifer system, which is composed predominant- ly of sandstone, shale, siltstone, and conglomerate, and a crystalline bedrock aquifer, which is composed predominantly of gneiss, schist, and marble. Metamorphosed carbonate rocks (marble), although crystalline, are delineated separately in figure 1 and are described separately in table 2 because they produce a distinctive water quality and slightly larger well yields. The sedimentary-aquifer system is composed of a thick sequence of Triassic and Jurassic sandstone, siltstone, shale, and conglomerate that underlies the Connecticut Valley Low- land and a small area in western Connecticut. Three basalt flows (igneous rocks) about 200 to 330 ft thick (Hubert and others, 1978) are interbedded with the sedimentary rocks. The hydrologic characteristics of this aquifer are defined poorly with respect to degree of confinement, permeability, and ground-water circulation, particularly in zones deeper than 300 ft. Well yields depend primarily on the number, size, and degree of interconnection of water-bearing fractures, especial- ly in the upper 300 ft of this aquifer. Analyses of the records of several hundred wells that tap the sedimentary-aquifer system indicate larger median and maximum yields than in the crystalline bedrock (Mazzaferro and others, 1979; Ryder and others, 1981; and Weiss and others, 1982). Relatively large yields, ranging from 100 to 600 gallons per minute at several locations in the Connecticut Valley Lowland, may be associat- ed with major fault zones. Crystalline bedrock aquifers underlie eastern and western Connecticut (fig. 1). Well yields depend upon the number, size, and degree of interconnection of the water-bearing fractures intercepted. Analyses conducted for regional studies indicate little areal variation in the water-yielding characteris- tics of crystalline bedrock (Cervione and others, 1972; Randall and others, 1966; Mazzaferro and others, 1979; Weiss and others, 1982). Carbonate rocks (marble) and the more struc- turally competent granular rocks (gneiss and granite gneiss) generally are more productive than schists. Large yields have been associated with major fault zones and with areas where the bedrock is overlain by saturated stratified drift. Water quality in the bedrock aquifers generally is suitable for most uses. Large concentrations of iron (as much as 8.6 mg/L) and manganese (as much as 6.4 mg/L) are common statewide, and hard to very hard water is widespread in the carbonate rocks in western Connecticut and in the sedimen- tary-aquifer system. Large concentrations of chloride (as much as 830 mg/L), sulfate (as much as 1,600 mg/L), and sodium (as much as 3,800 mg/L) are present in some parts of the sedimentary-aquifer system, particularly in deeper wells. The bedrock aquifers also have been contaminated locally by inorganic and organic substances (Rolston and others, 1979); the major sources of contamination are summarized in Hand- man and others (1979). GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Areas of major ground-water withdrawals are concentrat- ed in Hartford, Fairfield, Middlesex and New Haven Counties (fig. 2). Most of the water is used for public supply. Pumping centers are located in stratified-drift aquifers with the excep- tion of one that taps the sedimentary aquifer system north of Hartford (location 4, fig. 2). Natural trends of ground-water levels in major aquifers are shown in the hydrographs of figure 2 (locations 26 and 27). The lowest water levels occurred during the drought period of the 1960's; high water levels in the early 1970's reflect higher than average rainfall. Water-level measurements near pump- ing centers are not available. Widespread, progressive water- level declines are unlikely because most pumping centers are located in unconfined stratified-drift aquifers near large streams and derive much of their water from induced recharge rather than aquifer storage. Records of discontinued U.S. Geological Survey observation wells in the New Haven area show progressive water-level declines that have been accom- panied by saltwater intrusion in a coastal stratified-drift aqui- fer. Water levels in this aquifer began to recover after with- drawals were reduced in the 1950's. Because of the widespread dependence on induced re- charge to sustain withdrawals from stratified-drift aquifers, the most significant impact of development is the depletion of streamflow. Withdrawal rates generally are greater in the summer when ground-water levels and streamflow are rela- tively low. A larger proportion of total streamflow may infiltrate the aquifer during this period and parts of small streams may become completely dry. GROUND-WATER MANAGEMENT Connecticut has a comprehensive program for managing ground-water resources that originated with passage of the Clean Water Act of 1967 (Connecticut Public Act 57) and that has been strengthened by subsequent passage of Federal clean water legislation. Joint management planning by the Connec- ticut Departments of Environmental Protection (DEP) and of Health Services (DOHS) and the Office of Policy and Man- agement is a continual process. Water-quality management is an important State activity. The Connecticut DEP is responsible for establishing quality goals for ground water and for planning regulatory programs to ensure that these goals are met. Water-quality standards for ground water, which were adopted in 1980 (Connecticut Department of Environmental Protection, 1980), provide the framework for basin-wide plans that specify actions to elimi- nate water-quality problems and for such regulatory programs such as waste-discharge permits and enforcement actions. Permits for drilling wells and submission of well records have been required by the State since 1955. The Connecticut Water Policy Diversion Act (Connecticut General Statutes, Sec. 22a-365) gives the DEP the authority to regulate ground- water withdrawals that exceed 50,000 gallons per day. The process for permitting withdrawals addresses issues of water quantity and quality. The DEP also is responsible for investi- gating pollution incidents, for providing technical assistance to municipalities, and for conducting inventories and investi- gations of the State's water resources. The inventories and investigations, done principally as part of a cooperative pro- gram with the U.S. Geological Survey, provide the scientific information base for the State's ground-water planning and management. Information needs for ground-water manage- ment that have been identified by the DEP (H. F. Thomas, Connecticut Department of Environmental Protection, oral commun., 1984) include definition of the flow system and water quality in principal stratified-drift aquifers, relations between land use and ground-water quality, and affects of induced recharge from waste-receiving streams. National Water Summary Connecticut 165 26 Stratified drift aquifer Unconfined j____i____i____i__ i 1955 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) 1.0-5 £ 5.1 - 10 Location number 4 Withdrawal site 26 o Hydrograph only 1975 27 Crystalline bedrock aquifer Unconfined 1975 WITHDRAWAL SITES No. on 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Geographic area Enfield ........ Enfield ........ Bl cornfield. ..... Plainville ....... Bristol ........ Simsbury. ...... Southington ..... Cheshire ....... Meriden ....... Wallingford ..... North Haven. .... Cheshire, Hamden. . Southbury ...... Seymour ....... Seymour, Derby, Shelton. Danbury ....... Westport ....... Norwalk ....... Haddam ....... Clinton, Guilford, Madison. Plainfield. ...... Montville. ...... Aquifer Stratified drift. . . . ... .do ........ ... .do ........ Sedimentary rock . . Stratified drift. . . . ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ ... .do ........ Principal uses Public supply. Do. Do. Commercial. Public supply. Do. Do. Do. Do. Do. Do. Do. Industrial. Public supply. Do. Do. Do. Do. Do. Do. Public supply, industrial. 1 ndustrial. Public supply. Aquaculture. Industrial. Figure 2. Area distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Connecticut. (Sources: Withdrawal data from Sternberg, 1983, and Connecticut Department of Environmental Protection files; water-level data from U.S. Geological Survey files.) 166 National Water Summary Ground-Water Resources The Connecticut DOHS, under Section 19-13 of the Connecticut General Statutes, has the major role in managing ground-water resources used for drinking water. Responsibili- ties include protection and location of private and public- supply wells, well-construction requirements, and develop- ment and enforcement of standards for the quality of drinking water. Public water-supply utilities are required by Connec- ticut Public Act 84-502 to submit long-range water-supply plans to DOHS to aid in identifying aquifers to be protected for future public supply. Programs designed to protect aqui- fers as sources of public supply were instituted by 25 munici- palities through 1983 using either local planning and zoning or municipal ordinances. Most of these programs include regula- tions that prohibit uses or activities that could adversely affect ground-water quality. SELECTED REFERENCES In addition to reports listed below, hydrologic and geologic information was derived from the series of Bulletins prepared cooperatively by the U.S. Geological Survey and the Connecticut Department of Environmental Protection and published by the Connecticut Department of Environmental Protection. Cervione, M. A., Jr., Mazzaferro, D. L., and Melvin, R. L., 1972, Water resources inventory of Connecticut; Part 6, Upper Housa- tonic River basin, Connecticut: Connecticut Water Resources Bulletin 21, 84 p. Connecticut Department of Environmental Protection, 1980, Connec- ticut water quality standards and criteria: Water Compliance Unit, 28 p. Fenneman, N. M., 1938, Physiography of Eastern United States: New York, McGraw-Hill Book Co., 714 p. Handman, E. H., Grossman, I. G., Bingham, J. W., and Rolston, J. L., 1979, Major sources of ground-water contamination in Connecticut: U.S. Geological Survey Water Resources Investi- gations Report 79-1069, 59 p. Hubert, J. F., Reed, A. A., Dowdall, W. L., and Gilchrist, J. M., 1979, Guide to the Mesozoic redbeds of central Connecticut: Connecticut Geological and Natural History Survey Guidebook 4, 129 p. Mazzaferro, D. L., Handman, E. H., and Thomas, M. P., 1979, Water resources inventory of Connecticut; Part 8, Quinnipiac River basin, Connecticut: Connecticut Water Resources Bulletin 27,85 p. Meade, D. B., 1978, Ground-water availability in Connecticut: Connecticut Geological and Natural History Survey, Natural Resources Atlas Series Map. Prisloe, Michael, Jr., and Sternberg, H. W., 1983, State of Connec- ticut public water supply water use State and county data: Connecticut Department of Environmental Protection, Connec- ticut Water-Use Information Program Report, 29 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Randall, A. D., Thomas, M. P., Thomas, C. E., Jr., and Baker, J. A., 1966, Water resources inventory of Connecticut; Part 1, Quinebaug River basin, Connecticut Water Resources Bulletin 8, 102 p. Rolston, J. L., Grossman, I. G., Potterton, R. S., Jr., and Handman, E. H., 1979, Places in Connecticut where ground water is known to have deteriorated in quality: U.S. Geological Survey Miscel- laneous Field Studies Map MF 981-G. Ryder, R. B., Cervione, M. A., Jr., Thomas, C. E., Jr., and Thomas, M. P., 1970, Water resources inventory of Connecticut; Part 4, Southwestern coastal river basins, Connecticut: Connecticut Water Resources Bulletin 17, 54 p. Ryder, R. B., Thomas, M. P., and Weiss, L. A., 1981, Water resources inventory of Connecticut; Part 7, Upper Connecticut River basin, Connecticut: Connecticut Water Resources Bulletin 24,78 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Sternberg, H. W., 1983, A 1980 survey of major water utilities in Connecticut: Connecticut Department of Environmental Protec- tion, Connecticut Water-Use Information Program Water Plan- ning Report 6,240 p. Weiss, L. A., Bingham, J. W., and Thomas, M. P., 1982, Water resources inventory of Connecticut; Part 10, Lower Connecticut River basin, Connecticut: Connecticut Water Resources Bulletin 31, 85 p. Prepared by Robert L. Melvin For further information contact Chief, Connecticut Office, U.S. Geological Survey, Abraham A. Ribicoff Federal Building, Room 525,450 Main Street, Hartford, CT 06103 U.S. Geological Survey Water-Supply Paper 2275 DELAWARE Ground-Water Resources National Water Summary Delaware 167 Table 1. Ground-water facts for Delaware [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983]____________________________ Population served by ground water, 1980 Ground water is the primary source of public, rural, and industrial water supply in 94 percent of the State of Delaware. Only the northernmost 6 percent of the State is supplied predominantly by surface water. Most of Delaware's popula- tion is concentrated in the northern part of the State; conse- quently, about 60 percent of the statewide population is served by ground water and 40 percent by surface water. Ground- Number (thousands) - ------------------ 354 water withdrawals in 1980 for various uses and related statis- JS^I^-^S?^:" ------------ « tics are given in table 1. Number (thousands) - ---------------- 254 Percentage of total population- ------------ 43 GENERAL SETTING From rural self-supplied systems: Delaware is situated in two physiographic provinces that are separated by the Fall Line (fig. 1). The Piedmont province Freshwater withdrawals, 1980 lies north of the Fall Line and comprises about 6 percent of the e* 4. /-i . «. A. r>- . . . ,,- Surface water and ground water, total (Mgal/d) ------- 140 State. Ground water in the Piedmont occurs in crystalline Ground water only (Mgal/d) -------------- 82 rocks. The Coastal Plain province, south of the Fall Line, Percentage of total- ----------------- 59 includes the remaining 94 percent of Delaware. The Coastal Percentage of total excluding withdrawals for Plain province is composed of a wedge-shaped deposit of thermoelectric power ---------------- 57 alternating layers of sand and clay that overlies the crystalline _____________Category of use_____________ basement rocks and increases in thickness to the southeast, Public-supply withdrawals: attaining a thickness of 15,000 feet (ft) in southeastern Dela- Ground water (Mgal/d)- - -------------- 30 & ' v ' Percentage of total ground water- ----------- 37 ware (Woodruff, 1977). Percentage of total public supply- ----------- 38 Most of the 43 inches (in.) of average annual precipitation Per capita (gal/d) ------------------ 118 in the Coastal Plain either evaporates, is transpired by plants, Rural-supply withdrawals: or runs off to streams and rivers. Johnston (1973) estimated Ground water (Mgal/d)- -------------- 25 that only about 14 in. of precipitation actually enters the Percentage of total ground water - ---------- 30 ground-water system annually. Although abundant fresh- Percentage of total rural domestic ---------- 100 water recharges the Coastal Plain aquifers, water 600 ft or Uvestod?* ^'^ ----------------- 25° more below land surface is generally saline. Ground water (Mgal/d)- -------------- 2.0 Percentage of total ground water ------------ 2 PRINCIPAL AQUIFERS Percentage of total livestock- ------------ 100 r-r JI-T^I i-jj Industrial self-supplied withdrawals: Two types of aquifers underlie Delaware: unconsohdated Ground water (Mgal/d)- --------------- 21 sedimentary deposits of the Coastal Plain and crystalline Percentage of total ground water- ----------- 26 bedrock of the Piedmont. The unconsolidated deposits are Percentage of total industrial self-supplied: , . .,. . , _ , Including withdrawals for thermoelectric power - - - - 68 the most important aquifers in the State. These deposits store Excluding withdrawals for thermoelectric power - - - - 73 and transmit water through interconnected pore spaces. The Irrigation withdrawals: bedrock aquifer stores and transmits water primarily through Ground water (Mgal/d)- --------------- 4.1 fracture networks and weathered surfaces of the bedrock. The pCTSSSoftoSlSiSrtioT"- - I - I I I ----- ~ 63 characteristics of the aquifers are described, from youngest to oldest, below and in table 2; their areal distribution is shown in figure 1. aquifers. Pollution from human activities has caused local Ground-water quality generally is suitable for human contamination of both crystalline rock and unconfined aqui- consumption and most other uses. Saline water occurs, how- fers. ever, in downdip parts of most Coastal Plain aquifers and at shallow depths in some aquifers that subcrop along Delaware UNCONFINED AQUIFER Bay and the Atlantic Ocean. Water in the confined Coastal The unconfined aquifer consists of channel-fill sands in Plain aquifer ranges in chemical character from calcium northern Delaware south of the Piedmont Province and of a bicarbonate water containing less than 100 milligrams per liter broad sheet of sand across central and southern Delaware. (mg/L) dissolved solids to sodium chloride-bicarbonate water The saturated thickness of the aquifer ranges from a few feet containing more than 1,000 mg/L dissolved solids. Some in much of northern Delaware to more than 180 ft in southern brackish water has been induced into the Potomac aquifer by Delaware (Johnston, 1973). The northern limit of the areally pumping near Delaware Bay. Locally large concentrations of continuous unconfined aquifer, which has a saturated thick- iron (more than 0.3 mg/L) and nitrate (more than 10 mg/L) ness of 25 ft or more, is shown in figure 1. This aquifer may limit the use of water from some of the unconsolidated supplies large quantities of water for public supply and irriga- 168 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Delaware [Gal/min = gallons per minute, ft = feet. Sources: Reports of the U.S. Geological Survey and Delaware Geological Survey] Well characteristics Aquifer name and description Depth (ft) Common May range exceed Yield (gal/min) Common May range exceed Remarks Unconfined aquifer: sand and gravel, some silt and clay. Chesapeake Group aquifers: Fine to coarse sand; layers of lignite and shells are common. Generally confined. Piney Point aquifer: Fine to medium glauconite sand. Confined. Rancocas aquifer: Fine to medium silty glauconite sand. Confined south of subcrop. Magothy aquifer: Clean quartz sand with layers of clayey silt. Confined south of subcrop area. Potomac aquifer: Silt and clay containing channel-fill deposits of sand and gravel. Confined south of subcrop area. Crystalline rock aquifer: Granodiorite, gabbro, schist, and marble. Unconfined. 25 -100 125 50-300 400 200-600 700 50-400 400 50-300 400 40-600 600 40-100 100 100 - 500 1,000 Concentrations of iron, nitrate, or chloride may exceed national drinking- water regulations in local areas. 100-500 1,000 Includes the Pocomoke, the Manokin, the Ocean City, and the Cheswold aquifers. In some areas, chloride or iron concentrations exceed national drinking-water regulations. 100-500 1,000 Important source of water for Dover. 50 -100 300 Equivalent to Aquia aquifer in Maryland. 10-25 50 Minor aquifer, used in southern New Castle County. 100-400 1,000 Major source of public and industrial water supply in central New Castle County. 5-20 200 Supplements surface-water supplies in the Piedmont. tion and also serves as a recharge area for the underlying aquifers of the Coastal Plain. Nitrate may exceed 10 mg/L as nitrogen in areas affected by agriculture or domestic sewage, and iron may exceed 30 mg/L in some areas of the unconfined aquifer. AQUIFERS IN CHESAPEAKE GROUP Aquifers in the Chesapeake Group generally are confined except where they subcrop beneath the unconfined aquifer. The Pocomoke, the Ocean City, and the Manokin aquifers are used in southern Delaware for public and industrial water supplies. The lowermost aquifer of the Chesapeake Group, the Cheswold aquifer, is an important source of water in Kent County. PINEY POINT AQUIFER The Piney Point aquifer is confined completely in Dela- ware. Recharge to this aquifer is derived from leakage of water through adjacent confining beds composed of silt and clay. The Piney Point aquifer, in conjunction with the Ches- wold aquifer described above, supplies about 80 percent of the total municipal and industrial water used in Kent County (Leahy, 1982). RANCOCAS AQUIFER The Rancocas aquifer supplies small to moderate amounts of water for public-supply, industrial, and agricul- tural use in southern New Castle County. Sundstrom and Pickett (1971) estimated that 650,000 gallons per day (gal/d) were withdrawn from this aquifer in 1966. MAGOTHY AQUIFER The Magothy aquifer receives recharge from the uncon- fined aquifer in central New Castle County. South of the recharge area the aquifer is confined and provides water for domestic, agricultural, and minor public-supply use. Water in the Magothy aquifer becomes salty about 6 miles (mi) south- east of Middletown (Sundstrom and Pickett, 1971). POTOMAC AQUIFER The Potomac aquifer is composed of several sandy zones within the Potomac Formation. These sandy zones are in- terbedded with variegated clay and differ considerably in lateral extent. Martin and Denver (1982) estimated that the Potomac aquifer provided 19.9 million gallons per day (Mgal/d) for industrial and public-water supply. This aquifer is the primary source of ground water in central New Castle County. CRYSTALLINE ROCK AQUIFER The Piedmont crystalline rocks of northern Delaware are composed of granodiorite, gabbro, schist, and marble. Ras- mussen and others (1957) found that of 165 wells in the granodiorite, gabbro, and schist, and their weathering products, those that produce water from the gabbro had the greatest average yield [28 gallons per minute (gal/min)]. Two wells subsequently completed in marble, however, produce an average of 600,000 gal/d. Well yields in this part of Delaware usually are small, averaging about 20 gal/min (Sundstrom and Pickett, 1971). 75°30' 39°30' Chesapeake Group aquifers National Water Summary Delaware 169 EXPLANATION Unconfined aquifer Pocomoke Ocean City aquifer Manokin aquifer Cheswold aquifer Piney Point aquifer Rancocas aquifer Magothy aquifer Potomac aquifer Crystalline rock aquifer Not a principal aquifer Northern limit of unconfined aquifer thickness greater than 25 feet 10 20 MILES NORTHWEST SOUTHEAST -800' - -1000 Figure 1. Principal aquifers in Delaware. A, Geographic distribution. B, Generalized cross section. (See table 2 for a more detailed description of the aquifers. Sources: A, Gushing and others, 1973; Sundstrom and Pickett, 1971; Hodges, 1984. B, Gushing and others, 1973; Sundstrom and Pickett, 1971; Hodges, 1984.) 170 National Water Summary Ground-Water Resources GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Major areas of ground-water withdrawals and trends in ground-water levels are shown in figure 2. The largest concen- tration of pumping is in central New Castle County where almost 20 Mgal/d is pumped for public-supply and industrial use. In Kent County, the city of Dover and Dover Air Force Base (location 4, fig. 2) withdraw a total of more than 6 Mgal/d. The largest use of water in Sussex County is for irrigation (location 8, fig. 2). Irrigation wells normally oper- ate for only 4 months each year. Average daily use during the growing season is, therefore, about three times the annual average value shown in the explanation. The hydrographs shown in figure 2 represent water-level trends near the major withdrawal centers of the Coastal Plain aquifers of Delaware. Increased growth of population and heavy industry in central New Castle County (location 1, fig. 2) caused a rapid decline of water levels in the Potomac aquifer during the late 1950's. A slight decrease in withdraw- als during the late 1960's and early 1970's allowed water levels to recover somewhat, but increased demand during the past 10 years has caused water levels to resume their decline. Develop- ment of the Piney Point aquifer as a source of public, industrial, and military water supply in the Dover area (loca- tion 4, fig. 2) began in 1957. Since that time, water levels in the aquifer have declined steadily. The unconfined aquifer, however, receives abundant recharge from precipitation. Water levels in this aquifer normally decline as much as 5 ft during the summer growing season and then recover during the winter and spring. GROUND-WATER MANAGEMENT Delaware ground-water use is regulated by the Depart- ment of Natural Resources and Environmental Control (DNREC) under the terms of the Delaware Environmental Protection Act (7 Delaware Code, chapter 60). The Water Supply Section of DNREC licenses well drillers, issues permits for the construction of all water wells, requires reports on the completion of these wells, and issues allocations for the use of ground and surface water. The DNREC also issues permits for onsite wastewater treatment installations, and monitors National Pollution Discharge Elimination System wastewater return-flow data. The Delaware Department of Health and Social Services, Division of Public Health (DPH) regulates the quality and adequacy of public water-supply systems (16 Delaware Code, 122) that provide service to three or more dwelling units, public or semipublic buildings, or to establishments that use water to prepare food or drink. Under this law, the DPH has the power to regulate the adequacy of source water as well as the adequacy of treated water and, under 16 Delaware Code, 1244, can regulate any activity within 1 mi of a source of public-water supply. Public-water supplies also are regulated by the Public Service Commission (PSC). The PSC, in addition to requiring adequacy of service, can function as an enforcement arm of the Department of Health, or of other State agencies. The Delaware River Basin Commission (DRBC), by agreement between the various States in the Delaware River basin, regulates the use of surface and ground water in that part of Delaware within the basin boundary. All projects within the basin that will have a "substantial impact" on water resources are subject to DRBC permit procedures. These projects include wells that withdraw an average of 100,000 gal/d or more during any calendar month, discharge or inject pollutants into ground water, or change land cover on major aquifer-recharge areas. Nonregulatory agencies involved in Delaware ground- water issues include the Water Resources Agency for New Castle County (WRANCC) and the Delaware Geological Survey (DCS). At present, the WRANCC is presently developing a plan titled "Water 2000," which is a management strategy for developing adequate present and future water supplies in New Castle County. In addition to other hydrolog- ic and geologic responsibilities, the DOS, in cooperation with the U.S. Geological Survey, maintains a statewide water-data network and investigates the ground-water resources of the State. National Water Summary Delaware 171 20 40 60 80 too 120 140 160 180 200 1 Potomac Group aquifer Confined 1955 1975 1965 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) Less than 5 5.0-25 Withdrawal site o Hydrograph only ir £u 1 « § 60 * B0 S TOO CO5 12° £ 160 0 1BO i 200 4 Piney Point aquifer Confined : . : V. - - i i i i i i i 1945 19SS J965 19?5 1985 au § 60 § 40 § 20 i ° 3 20 CO g 40 < 80 ffilOO 13 Unconfined aquifer Unconfined - Missing record / _ ~ - - 1 1 1 | 1 1 I 1955 1975 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 Geographic erea Naw Castle County . . Milford. ........ Milton ......... Rehoboth area. .... Bethany Beach area. . Aquifer Unconfined, Potomac Group. Unconfined, Rancocas, Magothy. Unconfined, Rancocas . . . Cheswold, Piney Point . . . Unconfined, Chesapeake Group. ... .do ............ Unconfined, Chesapeake Group. Unconfined ......... Unconfined, Chesapeake Group. ... .do ............ Principal uses Public supply, industrial. Public supply. Public supply industrial, institutional. Public supply, industrial, thermoelectric power. Public supply. Public supply, industrial. Irrigation. Do. Public supply, industrial. Public supply. Public supply, industrial. Do. Figure 2. Area! distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Delaware. (Sources: Withdrawal data from Delaware Department of Natural Resources and Environmental Control; water-level data from U.S. Geological Survey files.) 172 National Water Summary Ground-Water Resources SELECTED REFERENCES Caron, John, MacArtor, June, and Tannian, Francis, 1979, A review of institutional and legal aspects of water supply policies in Delaware, part 2: Water Resources Section, Delaware Depart- ment of Natural Resources and Environmental Control, Dover, Del., 80 p. Gushing, E. M., Kantrowitz, I. H., and Taylor, K. R., 1973, Water resources of the Delmarva Peninsula: U.S. Geological Survey Professional Paper 882, 58 p. Hodges, A. L., Jr., 1984, Hydrology of the Manokin, Ocean City and Pocomoke aquifers of southeastern Delaware: Delaware Geo- logical Survey Report of Investigations No. 38,60 p. Johnston, R. H., 1973, Hydrology of the Columbia (Pleistocene) deposits of Delaware: Delaware Geological Survey Bulletin 14, 78 p. Leahy, P. P., 1982, Ground-water resources of the Piney Point and Cheswold aquifers in central Delaware as determined by a flow model: Delaware Geological Survey Bulletin No. 16, 68 p. Martin, M. M., and Denver, J. M., 1982, Hydrologic data for the Potomac Formation in New Castle County, Delaware: U.S. Geological Survey Water Resources Investigations Open-File Report 81-916,148 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Rasmussen, W. C., Groot, J. J., Martin, R. O. R., and others, 1957, The water resources of northern Delaware: Delaware Geological Survey Bulletin 6, v. 1, 223 p. Solley, W. B., Chase, E. B., Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Sundstrom, R. W., and Pickett, T. E., 1971, The availability of ground water in New Castle County, Delaware: University of Delaware, Water Resources Center, 156 p. Woodruff, K. D., 1977, Preliminary results of seismic and magnetic surveys off Delaware's coast: Delaware Geological Survey Open-File Report 10,19 p. Prepared by Arthur L. Hodges, Jr. For further information contact Chief, Delaware Office, U.S. Geological Survey, Federal Building, Room 1201, 300 S. New Street, Dover, DE 19901 National Water Summary Florida 173 FLORIDA Ground-Water Resources Table 1. Ground-water facts for Florida [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] Population served by ground water, 1980 Florida contains abundant ground-water resources. Large quantities of water are obtainable from each of the principal aquifers in most areas of the State. The State also contains 27 of the 78 first-magnitude springs in the United States (Heath and Conover, 1981, p. 131). Because of its abundance and availability, ground water is the principal source of freshwater for public-supply, rural, and industrial Number (thousands) . ................. 8>750 uses, and is the source for about half of the water used for Percentage of total population ------------- 90 irrigation. More than one-half of the 7,300 million gallons per From public water-supply systems: day (Mgal/d) of freshwater used in Florida for all purposes Number (thousands) ---------------- 6,800 comes from ground-water sources (Leach, 1983), and about 90 Percentage of total population - ----------- 70 percent of Florida's population depends on ground water for From rural self-supplied systems: its drinking water (table 1). Nationally, Florida ranks eighth SSSSi?S?SSd?(i,iilaii«I -" I I I I I I I I -" I 20 among States in total fresh ground-water withdrawals for all - - ; uses, second for public supply, first for rural domestic and __________Freshwater w.thdrawals, 1980_______ livestock, third for industrial uses, and ninth for irrigation Surface water and ground water, total (Mgal/d) ------ 7,300 withdrawals (Solley and others, 1983). Ground water is one of Ground water only (Mgal/d) -------------- 3,800 _, . , , \ i .1 1 Percentage of total- ---------------- 52 Florida's most valuable natural resources. Percentage of total excluding withdrawals for GENERAL SETTING thermoelectric power --------------- 69_ The entire State is in the Coastal Plain physiographic ategoryo use_____________ province, which is a region that has generally low relief and is Public-supply withdrawals: underlain by unconsolidated to poorly consolidated sediments gSSSSSSS^Snd'wa^I I I I I I I I I I I ^ and indurated carbonate rocks. Florida is mantled nearly Percentage of total public supply - ---------- 86 everywhere by surficial sands that overlie a thick sequence of Per capita (gal/d) ----------------- 176 bedded limestone and dolomite. Together, the surficial sands Rural-supply withdrawals: and the limestone and dolomite form an enormous ground- Domestic: water reservoir that provides proportionally larger quantities gSSj£5£2S^~water = I - = = = I - = = I *? of ground water in Florida than in any other State (McGum- Percentage of total rural domestic ---------- 100 ness, 1963, p. 244). Nearly all of Florida's ground water Per capita (gal/d) ----------------- 128 originates from precipitation. Relatively small amounts also Livestock: are supplied by subsurface inflow from adjacent areas of Ground water (Mgal/d) - -------------- 39 Alabama and Georgia and by leakage from streams that enter Percentage of total ground water - ---------- 1 p. ., Percentage of total livestock - ------------ 66 Florida. Industrial self-supplied withdrawals: Average annual precipitation (1951-80) exceeds 50 inches Ground water (Mgal/d)- --------------- 710 (in.) over most of the State. Part of this precipitation perco- Percentage of total ground water- ----------- 19 lates to the water table and recharges the ground-water reser- Percentage of total industrial self-supplied: voir. Annual recharge rates range from near zero in perennial- Including withdrawals for thermoelectric power - - - - 27 ly we,, lowland areas to as much as 20 in. or more in IrrigJ^j^rals for "" >*«*"«- ' ' ' ' 82 well-drained upland areas. In much ot the state, most ot this Ground water (Mgal/d)- -------------- i,600 recharge moves through the surficial aquifers and discharges Percentage of total ground water ----------- '42 to nearby streams; only a small fraction, ranging from nearly Percentage of total irrigation ------------ 53 0 to 5 in. (Bush, 1982), percolates downward to recharge deeper aquifers. less permeable to the north and east. The high permeability is DCJIM^IDAI Artinrrcic caused largely by extensive carbonate dissolution. Large- PRINCIPAL AQUIFERS diameter public-supply wells in Bade County produce as much Principal aquifers of Florida are described below and in as 7,000 gallons per minute (gal/min), with little water-level table 2, from youngest to oldest; their areal distribution is drawdown. Water in the Biscayne aquifer is unconfined and shown in figure 1. in hydraulic continuity with the many canals that cross the area. Induced recharge from the canals occurs where the BISCAYNE AQUIFER water table is depressed below canal stage near well fields. The Biscayne aquifer is the most intensively developed of Water-level stages in the canals are controlled by structures all the Florida aquifers. It supplies the densely populated near their mouths to prevent saltwater from flowing inland to Miami-Palm Beach coastal area with virtually all of its water the well fields and, there, infiltrating the aquifer, needs. The Biscayne aquifer underlies all of Bade and Brow- Because the Biscayne aquifer is very permeable and very ard Counties and adjoining parts of Palm Beach and Monroe vulnerable to contamination and is the sole source of drinking Counties. It is primarily highly permeable limestone in south water for more than 3 million people in southeast Florida, the and west Bade County but becomes increasingly sandy and U.S. Environmental Protection Agency has designated it as a 174 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Florida [Mgal/d = millions of gallons per day; gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Reports of the U.S. Geological Survey and Florida State agencies; water withdrawals from Healy, 1981, data for public supply only] Well characteristics Aquifer name and description Water withdrawals (Mgal/d) Depth (ft) Common range Yield (gal/min) Common May range exceed Remarks Surficial aquifers: Biscayne aquifer: Limestone, sandstone, and sand. Unconfined. 461 40-150 500-1,000 7,000 Sand-and-gravel aquifer: Sand and gravel interbedded with discontinuous clay layers. Unconfined in upper part to locally confined in deeper part. Unnamed surficial aquifers: Sand, shell, and clayey sand; locally contains thin discontinuous limestone layers. Unconfined to locally confined. Intermediate aquifer(s): Limestone and shell beds with discontinuous clay layers and some interbedded sand. Confined. 34 100-300 500-1,000 2,000 50 - 400 <100 1,000 104 100-600 <200 1,000 Floridan aquifer system: Limestone and dolomite. Unconfined in outcrop areas, confined where deeply buried. 460 100-1,800 500-1,000 20,000 Supplies all public-supply water systems in southern Palm Beach, Broward, and Dade Counties. Designated by U.S. Environmental Protection Agency as "sole- source" drinking-water supply. Aquifer managed carefully to control saltwater intrusion into coastal well fields. Water generally very hard. Primary water source for Pensacola and other public-supply and private pumpage in Escambia and Santa Rosa Counties. Water soft; little dissolved solids (less than 50 mg/L), but locally iron exceeds 0.3 mg/L. Known as Pliocene-Miocene aquifer in Alabama. Locally important as water sources where deeper aquifers contain saline water, especially along east coast and in southwest Florida. Hardness and dissolved- solids concentrations vary widely. Saltwater intrusion a local problem. Important public-supply source along west coast from Sarasota to Lee County. Elsewhere tapped generally for small to moderate supplies. Flowing wells common in coastal areas. Some parts in and around Sarasota County yield water containing sulfate and radionuclide concentrations exceeding National drinking- water regulations. Also called "secondary artesian aquifer(s)." Occurs throughout Florida and extends into parts of Alabama, Georgia, and South Carolina. Contains nonpotable, saline water in south Florida, westernmost Florida panhandle, and locally along the west coast where Unconfined. Elsewhere water is hard. Locally sulfate concentrations exceed National drinking-water regulations. Principal source of water for all uses where water is fresh. Also called "principal artesian aquifer" and "Floridan aquifer." "sole-source aquifer" under provisions of the Safe Drinking Water Act of 1974 (Public Law 93-523). Locally, the aquifer has been contaminated by industrial discharges, landfill lea- chate, and fuel spills. SAND-AND-GRAVEL AQUIFER The sand-and-gravel aquifer is the major source of water supply in the western part of the Florida Panhandle. The aquifer consists of surficial sediments that exceed 700 feet (ft) in thickness in northwestern Escambia County. The aquifer thins to the south and east and pinches out in central Walton County. Water in the sand-and-gravel aquifer is under both unconfined and confined conditions, depending on the pre- sence of discontinuous clay lenses of little permeability that are interbedded with the more permeable sand-and-gravel layers. The deep production zone of the aquifer, which is National Water Summary Florida 175 86° 85 Biscayne aquifer Sand and gravel aquifer n Unnamed surficial aquifers and intermediate aquifers, undifferentiated Floridan aquifer system Maiquesss , Kev9 ' Figure 1. Principal aquifers in Florida. A, Approximate area! extent over which principal aquifers are the primary source of supply. B, Physiographic diagram. (See table 2 for a more detailed description of the aquifers. Source: A, Modified from Franks, 1982. B, Raisz, 1954.) 176 National Water Summary Ground-Water Resources tapped by most large-capacity wells, generally is semicon- fined. Wells capable of producing several hundred gallons per minute are common. Industrial operations in and around Pensacola have caused local contamination of the aquifer's water; a noteworthy example is contamination by phenol and pentachlorophenol from a wood-preserving plant during the past several decades (Mattraw and Franks, 1984). UNNAMED SURFICIAL AND INTERMEDIATE AQUI- FERS Unnamed surficial aquifers are present over much of the remainder of the State but they are little used where more plentiful supplies are obtained from deeper aquifers that contain potable water. Where the deeper aquifers contain nonpotable water, these surficial aquifers are important sources of supply. The surficial deposits consist of sand and shell with minor limestone beds. These aquifers are used most intensively for public supply in the area southwest of Lake Okeechobee and in scattered towns along the east coast from Palm Beach County northward. Elsewhere, these aquifers are used mainly for rural supplies. The aquifers have been con- taminated locally with saline water from uncontrolled flowing artesian wells that tap deeper aquifers. In south Florida and along the eastern part of peninsular Florida, one or more aquifers are present between the local surficial aquifer and the underlying Floridan aquifer system; these are informally referred to as intermediate aquifers. The rocks that contain the intermediate aquifers are mainly lime- stone and shell beds interbedded with sand and clay. Inter- mediate aquifers are an important source of water for public supply and irrigation in coastal southwestern Florida from about Sarasota County to Lee County where the underlying Floridan aquifer system contains nonpotable water. Well yields differ widely depending on the amount of permeable limestone available; however, yields of 1,000 gal/min or more can be obtained. Elsewhere, these aquifers generally are used only for rural or small-community supplies. Water in the intermediate aquifers is confined. The intermediate aquifers contain water too saline for human consumption in most of the area south of Lake Okeechobee. Parts of the aquifers in and around Sarasota County contain water having concentra- tions of naturally-occurring radium 226 that exceed national drinking-water standards (U.S. Environmental Protection Agency, 1982). FLORIDAN AQUIFER SYSTEM The Floridan aquifer system, one of the most productive sources of ground water in the United States, extends across the entire State of Florida, southern Georgia, and adjoining small parts of Alabama and South Carolina. The Floridan is the lowermost part of the ground-water reservoir in Florida. It consists of as much as 3,500 ft of limestone and dolomite beds that are interconnected hydraulically to differing degrees. The Floridan is at or near land surface in the western part of the peninsula that extends from Wakulla to Pasco County and in most of Holmes and Jackson and a small part of Walton Counties in the panhandle area bordering Alabama. Else- where, it is buried to depths as much as 1,100 ft below sea level in southern Florida and 1,500 ft below sea level in the western- most part of the Florida Panhandle. Water in the Floridan is unconfined in about one-quarter of the State, where the aquifer system is at or near land surface, and is confined elsewhere. Many public-supply systems tap the Floridan aquifer system including those serving Jacksonville, Orlando, Clear- water (Pinellas County), St. Petersburg (Pinellas County), and Tallahassee. The Floridan also is a major source of water for industrial, irrigation, and rural uses. Total pumpage from the aquifer system in Florida exceeds 2 billion gallons per day (Peter W. Bush, U.S. Geological Survey, written commun., 1984). Yields vary considerably, but yields of several hundred to a thousand gallons per minute commonly are attainable by large-diameter wells, and yields of as much as 20,000 gal/min have been reported (Heath and Conover, 1981, p. 159). Flowing artesian wells that tap the Floridan are common over much of the lower lying areas of the State. The entire aquifer system contains nonpotable water in the southern one-third of the peninsula. Contamination by aldicarb and ethylene dibro- mide from agricultural activities has been noted recently in parts of the State (J. E. McNeal, Florida Department of Environmental Regulation, written commun., 1983; S. H. King, Florida Department of Health and Rehabilitative Ser- vices, written commun., 1983). Where the aquifer is at or near land surface, it is susceptible to contamination by leachate from landfills and other waste-disposal facilities. Besides its wide use as a water-supply source, the Floridan aquifer system also is used as a repository for wastewaters. Stormwaters enter the upper part of the aquifer system through hundreds of drainage wells, mostly in central peninsu- lar Florida (Kimrey and Fayard, 1984). Industrial and munici- pal wastewaters are injected into saline parts of the aquifer system mainly in the Pensacola area, in Pinellas County, and along the southeastern coast from Miami to Indian River County (Vecchioli, 1981). GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS The distribution of major ground-water withdrawals and trends of ground-water levels near selected pumping centers are shown in figure 2. Fresh ground-water withdrawals in 1980 exceeded 1 Mgal/d in every county but Liberty (Leach, 1983). Withdrawals were greatest in Dade and Polk Counties (433 and 312 Mgal/d, respectively). The hydrographs in figure 2 show the response of the principal aquifers to pump- ing at selected withdrawal centers. Water levels in the Biscayne aquifer respond to the large amount of pumpage in the Miami area (location 1, fig. 2) for public supply, but, because the Biscayne is unconfined and readily recharged by infiltration of canal water and precipita- tion, the response is seasonal and small in magnitude. How- ever, these small declines are of concern because of the potential for saltwater intrusion into the coastal well fields. Withdrawals in the Pensacola area (location 17, fig. 2) from the sand-and-gravel aquifer have caused water levels to decline somewhat, but the trend has stabilized over the last decade. The production zone in the aquifer is semiconfined to confined. Water levels in the confined Floridan aquifer system in Polk County (location 2, fig. 2) have declined since the early 1950's in response to large withdrawals, primarily for the phosphate-mining industry and secondarily for irrigation. Water levels have recovered somewhat since the mid-1970's because of artificial recharge practices implemented by the phosphate industry and a reduction in pumpage due to water recycling. In the Orlando area of Orange County (location 5, fig. 2), water levels in the confined Floridan also have declined in response to large withdrawals for irrigation and public supply. The magnitude of these water-level declines has been reduced by the recharge of stormwater through more than 400 drainage wells. Where unconfined, water levels in the Flori- dan have been little affected by withdrawals on a long-term basis. Overall, only four areas in Florida have experienced water-level declines of more than 10 ft in the Floridan aquifer National Water Summary Florida 177 10 8 £ 0 cfi 10 I! 2" ;*40 1 Biscayne aquifer V Unconfined 22 1935 1945 1955 1965 1975 1985 EXPLANATION 20 40 50 2 Floridan aquifer Confined Ground-water withdrawals, 1960 (mfflion gallons per day) 50 - 99 9 100 - 149 O 150 - 199 200-600 Withdrawal site 1935 1945 1955 1965 1975 1985 £ 0 sj~! to 5 Floridan aquifer Confined 840 ^ 50 i i 60 o S 80 | 90 17 Sand and gravel aquifer Confined 1935 1945 1955 1965 1975 1985 1935 1945 1985 WITHDRAWAL SITES No. on 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Geographic area Miami area .................... Bartow area ................... Broward County coastal area ......... Brevard County ................. Orlando area. .................. Palm Beach County coastal area. ....... Hillsborough County .............. Jacksonville ................... Hendry County ................. Collier County. ................ Pasco County .................. Lake County. .................. Highlands .................... Indian River County .............. Okeechobee County ...... ....... Manatee County. ................ Pensacola area. ................. Lee County ................... St. Lucie County ................ Putnam County ................. Seminole County ................ Fernandina Beach area ............. Taylor County. ................. Volusia County ................. Pinellas County ................. Aquifer . . . . . Biscayne ............ . . . . . Floridan ............ . . . . . Biscayne ............ . . . . . Floridan ............ . . . . . ... .do ............. . . . . . Surficial ............ . . . . . Floridan ............ . . . . . ... .do ............. . . . . . Surficial ........... . . . . . ... .do ............. . . . . . Floridan ............ . . . . . ... .do ............. . . . . . ... .do ............. . . . . . ... .do ............. . . . . . ... .do ............. . . . . . ... .do ............. . . . . . Sand and gravel ........ . . . . . Intermediate. ......... . . . . . Floridan ............ . . . . . ... .do ............. . . . . . ... .do ............. . . . . . ... .do ............. . . . . . ... .do ............. . . . . . ... .do ............. . . . . . ... .do ............. Principal uses . . Public supply. . . Mining. . . Public supply. . . Irrigation. . . Irrigation, public supply. . . Public supply. . . Irrigation, public supply. . . Public supply, industrial. . . Irrigation. . . Do. . . Public supply. . . Irrigation. . . Do. . . Do. . . Do. . . Do. . . Industrial, public supply. . . Irrigation. . . Do. . . Irrigation, industrial. . . Irrigation, public supply. . . Industrial. . . Do. . . Public supply, irrigation. . . Public supply. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Florida. (Sources: Withdrawal data from Leach, 1983; water-level data from U.S. Geological Survey files.) 178 National Water Summary Ground-Water Resources system from 1961 through 1980 (Healy, 1982); in addition to the two areas mentioned above, the Jacksonville (Duval County) and Fort Walton Beach (Okaloosa County) areas also have been affected. GROUND-WATER MANAGEMENT The Florida Water Resources Act of 1972 established authority for management of the State's water resources through five water-management districts under the Florida Department of Natural Resources. The five districts, which encompass the entire State, include the Northwest Florida Water Management District, the Suwannee River Water Man- agement District, the St. Johns River Water Management District, the Southwest Florida Water Management District, and the South Florida Water Management District. The Act, among other things, empowered the districts to permit well drilling and the withdrawal of ground water for consumptive use that is shown to be reasonable or beneficial. Later, the Florida Environmental Reorganization Act of 1975 created the Department of Environmental Regulation and transferred to it all powers and functions of the Department of Natural Resources relating to water management. Since 1975, the five water-management districts have functioned within the Department of Environmental Regulation and generally have been delegated the primary responsibility for quantity-related aspects of water management; the Department of Environ- mental Regulation is concerned primarily with quality-related aspects of water management. Permitting regulations, which differ from district to district, control the construction of wells 2 inches or more in diameter and the withdrawal of ground water for all uses except private domestic use and minor other uses through consumptive-use permitting. Two of the districts have set threshold values (greater than 100,000 gallons per day average use, greater than 1 Mgal/d maximum capacity, or greater than 6-in. diameter well) below which users are not required to obtain a consumptive-use permit, and a third includes zones with differing requirements. Permitting regulations pertain- ing to waste disposal or other activities that impact on ground-water quality are administered directly by the Depart- ment of Environmental Regulation. Recently, the Florida Water Quality Assurance Act of 1983 made the Department responsible for establishing a statewide ground-water-quality monitoring network and a centralized data base for the acquired information. The Department of Environmental Regulation and the individual water management districts each have a cooperative water-resources program of study with the U.S. Geological Survey. Through these cooperative programs, much of the hydrologic data and interpretive information needed to man- age the quality and quantity of Florida's ground water are made available. SELECTED REFERENCES Bush, P. W., 1982, Predevelopment flow in the Tertiary limestone aquifer, southeastern United States A regional analysis from digital modeling: U.S. Geological Survey Water-Resources Investigations 82-905,41 p. Dysart, J. E., Pascale, C. A., Trapp, Henry, Jr., and others, 1977, Water resources inventory of northwest Florida: U.S. Geologi- cal Survey Water-Resources Investigations 77-84, 114 p. Prepared by John Vecchioli and Donald W. Foose Fenneman, N. M., 1928, Physical divisions, p. 60, in U.S. Geological Survey, 1970, National Atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Franks, B. J., ed., 1982, Principal aquifers in Florida: U.S. Geologi- cal Survey Water-Resources Investigations Open-File Report 82-255, [maps]. Healy, H. G., 1981, Estimated pumpage from ground-water sources for public supply and rural domestic use in Florida, 1977: Florida Bureau of Geology Map Series No. 102. __1982, Potentiometric surface of the Floridan aquifer in Florida, May 1980: Florida Bureau of Geology Map Series No. 104. Heath, R. C., and Conover, C. S., 1981, Hydrologic almanac of Florida: U.S. Geological Survey Open-File Report 81-1107, 239 p. Johnston, R. H., Healy, H. G., and Hayes, L. R., 1981, Potentiomet- ric surface of the Tertiary limestone aquifer system, southeastern United States, May 1980: U.S. Geological Survey Open-File Report 81-486, [map]. Kimrey, J. O., and Fayard, L. D., 1984, Geohydrologic reconnais- sance of drainage wells in Florida: U.S. Geological Survey Water-Resources Investigations Report 84-4021, 67 p. Klein, Howard, and Hull, J. E., 1978, Biscayne aquifer, southeast Florida: U.S. Geological Survey Water-Resources Investigations 78-107, 52 p. Leach, S. D., 1983, Source, use, and disposition of water in Florida, 1980: U.S. Geological Survey Water-Resources Investigations 82-4090, 337 p. Mattraw, H. C., Jr., and Franks, B. J., eds., 1984, Movement and fate of creosote waste in ground water, Pensacola, Florida U.S. Geological Survey Toxic Waste Research Ground-Water Contamination Program: U.S. Geological Survey Open-File Report 84-466, 93 p. McGuinness, C. L., 1963, The role of ground water in the national water situation: U.S. Geological Survey Water-Supply Paper 1800,1121 p. Miller, J. A., 1984, Hydrogeologic framework of the Floridan aquifer system in Florida and in parts of Georgia, South Carolina, and Alabama: U.S. Geological Survey Professional Paper 1403-B. [In press.] Parker, G. G., Ferguson, G. E., Love, S. K., and others, 1955, Water resources of southeastern Florida: U.S. Geological Survey Wa- ter-Supply Paper 1255,965 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C.,U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Sprinkle, C. L., 1982, Dissolved-solids concentration in water from the upper permeable zone of the Tertiary limestone aquifer system, southeastern United States: U.S. Geological Survey Water-Resources Investigations Open-File Report 82-94, [map]. Stewart, J. W., 1980, Areas of natural recharge to the Floridan aquifer in Florida: Florida Bureau of Geology Map Series No. 98. Stringfield, V. T., 1966, Artesian water in Tertiary limestone in the southeastern States: U.S. Geological Survey Professional Paper 517, 226 p. U.S. Environmental Protection Agency, 1982, Maximum contami- nant levels (Subpart B of part 141, National interim primary drinking water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100 to 149, revised as of July 1, 1982, p. 315-318. Vecchioli, John, 1981, Subsurface injection of liquid waste in Florida, United States of America: The Science of the Total Environ- ment, Amsterdam, Elsevier Scientific Publishing Co., p. 127-136. For further information contact District Chief, U.S. Geological Survey, 227 North Bronough Street, Suite 3015, Tallahassee, FL 32301 U.S. Geological Survey Water-Supply Paper 2275 GEORGIA Ground-Water Resources National Water Summary Georgia 179 Table 1. Ground-water facts for Georgia [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] __ ___ _____ Population served by ground water, 1980 Ground water is an abundant natural resource in Georgia and comprises 18 percent of the total freshwater used (includ- ing thermoelectric) in the State. Georgia's aquifers provide water for more than 2.6 million people, or almost one-half of the total population of the State. Of this number, about one-half are served by public water-supply systems and one- half by rural water-supply systems. Most ground-water with- Number (thousands) - ----------------- 2,604 drawals are in the southern one-half of the State where the Percentage of total population -------------- 48 aquifers are very productive. Ground-water withdrawals in From public water-supply systems: 1980 for various uses, and related statistics, are given in table Number (thousands) - --------------- 1,320 j_ Percentage of total population- ------------ 24 From rural self-supplied systems: Number (thousands) ---------------- 1,284 Percentage of total population- ------------ 23 GENERAL SETTING _________Freshwater withdrawals, 1980________ Differing geologic features and landforms of the several Surface water and ground water, total (Mgal/d) ------ 6,700 physiographic provinces of Georgia cause significant differ- Ground water only (Mgal/d) -------------- 1,200 ences in ground-water conditions from one part of the State to Percentage of total- ----------------- is another (fig. 1). The most productive aquifers in the State are Percentage of total excluding withdrawals for i * j rL ^i i r»i i_ i. LIT thermoelectric power ---------------- 52 located in the Coastal Plain province in the southern one-half - of Georgia; the province is underlain by alternating layers of _____________Category of use_____________ sand, clay, and limestone that dip and thicken to the south- Public-supply withdrawals: east. Aquifers generally are confined in the Coastal Plain, Ground water (Mgal/d)- --------------- 230 except near their northern limit where the formations are Percentage of total ground water - ----------- 19 exposed or are near land surface. Principal aquifers of the P^capf^a}^ ^ - I I I I I I I I I I I ill Coastal Plain include the Floridan aquifer system, the Rural-supply withdrawals: Claiborne aquifer, the Clayton aquifer, and the Cretaceous Domestic: aquifer system (table 2). The Piedmont and Blue Ridge Ground water (Mgal/d)- -------------- 140 provinces, which include most of the northern one-half of Percentage of total ground water - ---------- 12 Georgia, are underlain by massive igneous and metamorphic Percentage of total rural domestic ---------- ioo i u + c -c c i i_-i- TT- *T 11 Per capita (gal/d) ----------------- 109 rocks that form aquifers of very low permeability. The Valley Livestock- and Ridge and Appalachian Plateaus provinces, which are in Ground water (Mgal/d)- -------------- 17 the northwestern corner of Georgia, are underlain by layers of Percentage of total ground water - ----------- i sandstone, limestone, dolostone, and shale of Paleozoic age. Percentage of total livestock - ------------ 61 Recharge to the ground-water system in Georgia is '^"^^^^Sr^S***8181 400 derived almost entirely from precipitation. Average annual PCTcentageStot^ground"water- I I I I I I I I I I I 34 precipitation based on the 30-year period of record (1941-70) Percentage of total industrial self-supplied: is about 50 inches (in.) statewide and ranges from about 44 in. Including withdrawals for thermoelectric power ----- 8 in the east-central part of the State to about 76 in. in the Excluding withdrawals for thermoelectric power - - - - 57 northeastern corner of the State. Of this amount, about 88 Irrigation withdrawals: ... , , . i * * \ Ground water (Mgal/d)- --------------- 380 percent is discharged to streams or is lost to evapotranspira- Percentage of total ground water - ----------- 32 tion, and about 12 percent enters the ground-water system as Percentage of total irrigation ------------- 66 recharge (Carter and Stiles, 1983). PRINCIPAL AQUIFERS FLORIDAN AQUIFER SYSTEM The Floridan aquifer system is one of the most productive ground-water reservoirs in the United States. More than 600 million gallons per day (Mgal/d) is withdrawn from the aquifer system in Georgia (1980), making it the principal source of ground water in the State. The aquifer system generally is confined but is semicon fined to unconfined near its northern limit and near areas of karst topography in the Dougherty Plain and near Valdosta. In parts of the area where the Floridan aquifer system is exposed or is near land surface, intensive pumping can contribute to the formation of sinkholes. Although water suitable for most uses can be obtained from the aquifer system throughout most of the Coastal Plain, water-quality problems have occurred in some areas. The following examples serve to illustrate the problem: (1) at Brunswick, the intrusion of brackish water into the aquifer system resulted in chloride concentrations of as much as 1,000 milligrams per liter (mg/L) in some wells (Wait and Gregg, 1973), (2) in the area of Wheeler and Montgomery Counties in central-south Georgia, naturally occurring radi- oactivity exceeds 25 picocuries per liter (S. S. McFadden, Georgia Geologic Survey, oral commun., September 1984), (3) in nearby Ben Hill County, barium concentrations of as much as 2.1 mg/L are present in some wells (S. S. McFadden, Georgia Geologic Survey, oral commun., September 1984), (4) at Valdosta, naturally occurring organic substances, color, and hydrogen sulfide gas have been a cause of concern (Krause, 1979), and (5) in the Dougherty Plain area, small concentrations of commonly used pesticides have been detect- ed in some farm wells (Hayes and others, 1983). 180 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Georgia [Ft = feet;gal/min = gallons per minute. Sources: Reportsof the U.S. Geological Survey and Georgia Geologic Survey] Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Floridan aquifer system: Limestone, dolomite, and calcareous sand. Generally confined. 40-900 1,000-5,000 11,000 Claiborne aquifer: Sand and sandy limestone. Generally confined. 20-450 150-600 1,500 Clayton aquifer: Limestone and sand. Generally confined. 40-800 250-600 2,150 Cretaceous aquifer system: Sand and gravel. Generally confined. 30-750 50-1,200 3,300 Paleozoic aquifers: Sandstone, limestone, and dolomite; storage is in regolith and fractures and solution openings in rock. Generally unconfined. 15-2,100 1-50 3,500 Crystalline rock aquifers: Granite, gneiss, schist, and quartzite; storage is in fractures in rock and in regolith. Generally unconfined. 40-600 1-25 500 Supplies 50 percent of ground water in State. Major users include the Savannah, the Brunswick, the Jesup, the St. Marys, the Albany, and the Dougherty Plain areas. Water-level declines at Savannah and Brunswick. Intrusion of brackish water from deeper zones at Brunswick. In some areas, water has natural radioactivity that exceeds State and national drinking- water regulations. Formerly called principal artesian aquifer. Major source of water in southwestern Georgia. Supplies industrial and municipal users at Dougherty, Crisp and Dooly Counties and provides irrigation water north of Dougherty Plain. Called Tertiary sands aquifer in South Carolina and Tennessee. Part of Tertiary sedimentary aquifer system in Alabama. Major source of water in southwestern Georgia. Supplies industrial and municipal users at Albany and provides irrigation water northwest of Albany. Water-level declines exceed 100 ft at Albany. Iron concentrations in Randolph County exceed national drinking- water regulations. Part of Tertiary sedimentary aquifer system in Alabama. Major source of water in east-central Georgia. Supplies water for kaolin mining and processing. Includes Providence aquifer in southwestern Georgia. Water-level declines greater than 50 ft at kaolin mining centers and 100 ft near Albany. Iron concentrations exceed national drinking-water regulations in some areas. Called Black Creek and Middendorf aquifers in South Carolina. Not laterally extensive. Limestone and dolomite aquifers most productive. Springs in limestone and dolostone aquifers discharge at rates of as much as 5,000 gal/min. Sinkholes can form in areas of intensive pumping. Water is generally of good quality, although contamination from septic tanks and farm waste reported in some areas. Laterally equivalent to Paleozoic carbonate aquifers in Alabama and Pennsylvanian sandstone aquifers in Alabama and Tennessee. Not laterally extensive. Water of good quality with exception of large concentrations of iron and manganese in some areas and contamination from septic tank effluent in densely populated areas. BLUE RIDGE VALLEY PROVINCE AND RIDGE * i SOJE ^ PROVINCE ANp APPALACHIAN ' y '" PLATEAUS ./PIEDMONT r;.' PROVINCE .>" ;*- . ' BLUE RIDGE PROVINCE VALLEY AND RIDGE PROVINCE AND APPALACHIAN PLATEAUS National Water Summary Georgia 181 Savannah River "Augusta 85 35 ""' TT?^ ? TT-* /i '.' t / ' f£- fi J^lJsZ f^KE^ W V; /' '? ^ J *pfflTT6es/rV; Y EXPLANATION Floridan aquifer system Claiborne aquifer Clayton aquifer Cretaceous aquifer system Paleozoic aquifers Crystalline rock aquifers J ^--. vt)f'"C>N JL -f\& iGILr ^-^WH^WA; 100 MILES I Figure 1. Principal aquifers in Georgia. A, Geographic distribution. B, Physiographic diagram and divisions. C, Block diagram showing principal aquifers and physiographic divisions. (See table 2 for a more detailed description of the aquifers. Sources: A, J. S. Clarke, U.S. Geological Survey, written commun., 1984. B, Fenneman, 1938; Raisz, 1954. C, Modified from Pierce and others, 1984.) 182 National Water Summary Ground-Water Resources CLAIBORNE AQUIFER The Claiborne aquifer is an important source of water in part of southwestern Georgia (fig. 1) and supplied an estimat- ed 36 Mgal/d in 1980, primarily for irrigation (McFadden and Perriello, 1983). Although the Claiborne aquifer yields water suitable for most uses over most of its extent, naturally occurring concentrations of dissolved solids and chloride in the south-central part of the State have been reported as 22,200 and 11,900 mg/L, respectively (Wait, 1960). CLAYTON AQUIFER The Clayton aquifer is an important source of water in southwestern Georgia (fig. 1), where it supplied an estimated 20 Mgal/d in 1980. Most of the withdrawals were for public supply (58 percent) and irrigation (35 percent). With the exception of large concentrations of iron (greater than 0.3 mg/L) in Randolph County, water from the aquifer is suitable for most uses (Clarke and others, 1984). CRETACEOUS AQUIFER SYSTEM The Cretaceous aquifer system is a major source of water in the northern one-third of the Coastal Plain (fig. 1). During 1980, the aquifer system yielded an estimated 128 Mgal/d, primarily for industrial and public-supply use. The aquifer system consists of sand and gravel that locally contain layers of clay and silt which function as confining beds. These confining beds locally separate the aquifer system into two or more aquifers. In southwestern Georgia, the Providence aquifer is part of the Cretaceous aquifer system. Water from the aquifer system is soft (less than 60 mg/L as calcium carbonate), has little dissolved solids (generally less than 100 mg/L), and is of a sodium bicarbonate type that is suitable for most uses. In the center of the area of usage (fig. 1), the iron concentration may be as much as 6.7 mg/L. PALEOZOIC AQUIFERS Water in the Paleozoic aquifers generally is unconfined, and storage is limited mainly to joints, fractures, and solution openings in the bedrock. During 1980, an estimated 33 Mgal/d was withdrawn from the Paleozoic aquifers, primarily for industrial supply. Wells that tap the Paleozoic aquifers yield differing amounts of water, depending on the aquifer used. Dolostone aquifers typically yield 5 to 50 gallons per minute (gal/min), whereas limestone and sandstone aquifers typically yield 1 to 20 gal/min; maximum reported yields from these aquifers are 3,500 and 300 gal/min, respectively. Springs discharge from the limestone and dolostone aquifers at rates of as much as 5,000 gal/min. Where the limestone and dolostone aquifers are near land surface, pumping can con- tribute to the formation of sinkholes. Water from wells and springs in the Paleozoic aquifers generally is suitable for most uses, although contamination from septic tanks and farm waste has been reported (Cressler and others, 1976). CRYSTALLINE ROCK AQUIFERS Although individual crystalline rock aquifers are not laterally extensive, collectively they yielded an estimated 99 Mgal/d in 1980, primarily for rural supply. Ground-water storage occurs in the regolith and where the rocks have joints, fractures, and other types of secondary openings (Cressler and others, 1983). Crystalline rock aquifers in these areas general- ly are unconfined and show a pronounced response to rainfall, although deep fracture systems commonly are confined. Water from the aquifers generally is suitable for most uses, and, with the exception of iron (as much as 14 mg/L) and manganese (as much as 1.5 mg/L), constituent concentrations rarely exceed national drinking-water regulations (U.S. Envi- ronmental Protection Agency, 1982a,b). In some densely populated areas, septic-tank effluent has contaminated the aquifers (Cressler and others, 1983). GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Major areas of ground-water withdrawals and trends in ground-water levels near selected pumping centers are shown in figure 2. With the exception of one center in the Valley and Ridge province (location 1, fig. 2), all major pumping centers are in the Coastal Plain, where aquifers are very productive. The largest pumping center is the Dougherty Plain area where ground-water withdrawal for irrigation exceeds 200 Mgal/d. The hydrographs shown in figure 2 reflect the responses of aquifers to pumping at selected pumping centers under a variety of hydrologic conditions. In the Floridan aquifer system, large cones of depression have formed at Savannah, Brunswick, Jesup, and St. Marys as a result of pumping for industrial and public supply. At Savannah (location 5, fig 2.), the water level has declined at least 160 feet (ft) since pumping began in the late 1800's (McCollum and Counts, 1964). The hydrograph shows that the water level declined 45 ft from 1954 to 1961 and less than 10 ft from 1961 to 1984. These changes reflect pumping patterns in the area. At Brunswick, the water level in the aquifer system declined 65 ft from predevelopment to 1964 (Wait and Gregg, 1973). The decline continued until 1982 (location 7, fig. 2), then rose about 10 ft as the result of a significant decrease in pumping by a major water user. Near Valdosta (location 9, fig. 2), the water level in the Floridan aquifer system responds to changes in recharge derived from streamflow and to local pumping. The hydro- graph shows a moderate long-term response to changing recharge rates and to pumping. Pumpage from the Floridan aquifer system in the Dougherty Plain area (location 11, fig. 2) is primarily for seasonal irrigation which, averaged over the year, exceeded 200 Mgal/d in 1980. In this area, pumpage is scattered widely. Some recharge to the Floridan aquifer system occurs locally. As a result, water-levels recover annu- ally. In the Albany area (location 10, fig. 2), water is with- drawn from the Tertiary Floridan aquifer system, the Claiborne aquifer, and the Clayton aquifer and the Creta- ceous Providence aquifer. Water-level declines of more than 100 ft have occurred in the Clayton and Providence aquifers (Clarke and others, 1983, 1984). The water level in the Clayton aquifer near withdrawal location 10 (fig. 2) generally declined from 1958 to 1984 in response to increased pumping for public supply and agriculture. The water level in the Cretaceous aquifer system has declined more than 50 ft since 1950 in areas of heavy pumping for public supply and industrial use. However, in the Huber- Warner Robins area (location 4, fig. 2), the water level has not declined significantly from 1975 to 1984 despite a slight increase in ground-water withdrawals during that period. GROUND-WATER MANAGEMENT Georgia has a comprehensive set of laws governing the quality and use of ground water. The Ground-Water Use Act of 1972 provided for the permitting of withdrawals for indus- trial and municipal use that exceed 100,000 gallons per day (gal/d) and authorized the Georgia Environmental Protection Division to issue regulations about reporting, timing of with- drawals, abatement of saltwater encroachment, well depth and spacing, and pumping levels or rates. Amendments to the National Water Summary Georgia 183 S 40 * 80 | 100 ui t20 | 140 S 160 4 Cretaceous aquifer Confined 1945 1955 1965 1975 1985 Sj 40 1? 60 § 80 ui 100 S 120 M5 HO ° 160 5 Roridan aquifer Confined EXPLANATION Ground-water withdrawals, 1980 (miNJon galore per day) O 0-24 25-49 O Withdrawal site 1945 1955 1975 1985 g 0 1 20 | « | " of (if 100 7 Floridan aquifer Confined 40 60 80 100 120 140 160 9 Floridan aquifer Confined 60 80 100 120 140 160 10 Clayton ^ aquifer Missing record Confined 1945 1955 1965 1975 1985 1945 1955 1965 1975 1985 1955 1975 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 Geographic erea Valley and Ridge . . Richmond-Burke . . Kaolin Belt. ..... Huber-Warner Robins. Savannah. ...... Jesup ......... St. Marys. ...... Valdosta ....... Albany ........ Dougherty Plain. . . Aquifer Cretaceous .... ... .do ...... ... .do ...... ... .do ...... ... .do ...... ... .do ...... ... .do ...... Floridan, Clay- ton, Claiborne, Providence. Principal uses Carpet mill industry. Public supply, industrial, irrigation. Clay mining and processing. Clay mining and proc- essing, public supply. Public supply, chemical industry, pulp and paper industry. Pulp and paper industry. Pulp and paper Industry, public supply. Pulp and paper industry. Public supply, industrial. Public supply, industrial, irrigation. Irrigation. 0 20 40 60 80 100 11 Roridan aquifer Semi-confined 1945 1955 1965 1975 1985 Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Georgia. (Sources: Withdrawal data from Pierce and others, 1982; water-level data from U.S. Geological Survey files.) 184 National Water Summary Ground-Water Resources Act in 1982 required that irrigation withdrawals in excess of 100,000 gal/d be reported to the State, although permits for that use still are not required. The Oil and Gas Deep Drilling Act of 1975 authorized the Board of Natural Resources to regulate drilling and use of oil, gas, and other types of wells for the purpose of protecting fresh ground-water supplies. The Georgia Safe Drinking Water Act of 1977 provides for regulation of water quality in public-water systems. The Georgia Environmental Protection Division (EPD) and its branches are responsible for enforcing all surface- water, ground-water, and water-quality laws. In 1984, a ground-water management plan for Georgia was implemented to identify key activities performed by EPD management, to control and regulate potential pollution sources, and to de- velop a monitoring program to provide water-quality and water-quantity data on the State's principal aquifers. The Water Resources Management Branch issues permits for ground-water withdrawals that exceed 100,000 gal/d by indus- trial and municipal users and oversees the reporting of ground-water use for irrigation in excess of 100,000 gal/d. The Ground-Water Program of the Water Protection Branch provides for the permitting of operators of public water-sup- ply systems that use ground water and monitors water quality for compliance with drinking-water standards. The Industrial and Hazardous Waste Management Program of the Land Protection Branch monitors ground water at hazardous waste sites. The Geologic Survey Branch provides technical support for the other branches and has a cooperative program with the U.S. Geological Survey that provides much of the basic data and interpretive information needed to manage the quality and quantity of ground water in the State. SELECTED REFERENCES Akioka, L. M., ed., 1980, 1980 Georgia statistical abstract: Athens, University of Georgia, College of Business Administration, 394 P- Clarke, J. S., Faye, R. E., and Brooks, Rebekah, 1983, Hydrogeology of the Providence aquifer of southwest Georgia: Georgia Geologic Survey Hydrologic Atlas 11. __1984, Hydrogeology of the Clayton aquifer of southwest Geor- gia: Georgia Geologic Survey Hydrologic Atlas 13. Carter, R. F., and Stiles, H. R., 1983, Average annual rainfall and runoff in Georgia, 1941-70: Georgia Geologic Survey Hy- drologic Atlas 9. Cressler, C. W., Franklin, M. A., and Hester, W. G., 1976, Avail- ability of water supplies in northwest Georgia: Georgia Geologi- cal Survey Bulletin 91, 140 p. Fenneman, N. M., 1938, Physiography of Eastern United States: New York, McGraw-Hill, 714 p. Cressler, C. W., Thurmond, C. J., and Hester, W. G., 1983, Ground Water in the greater Atlanta region, Georgia: Georgia Geologic Survey Information Circular 63, 144 p. Hayes, L. R., Maslia, M. L., and Meeks, W. C., 1983, Hydrology and model evaluation of the principal artesian aquifer, Dougherty Plain, southwest Georgia: Georgia Geologic Survey Bulletin 97, 93 p. Krause, R. E., 1979, Geohydrology of Brooks, Lowndes, and western Echols Counties, Georgia: U.S. Geological Survey Water- Resources Investigations Open-File Report 78-117, 48 p. Kundell, J. E., 1978, Ground water resources of Georgia: Athens, University of Georgia, Institute of Government, 139 p. McCollum, M. J., and Counts, H. B., 1964, Relation of salt-water encroachment to the major aquifer zones, Savannah area, Geor- gia and South Carolina: U.S. Geological Survey Water-Supply Paper 1613-D, 26 p. McFadden, S. S., and Perriello, P. D., 1983, Hydrogeology of the Clayton and Claiborne aquifers in southwestern Georgia: Geor- gia Geologic Survey Information Circular 55, 59 p. Pierce, R. R., Barber, N. L., and Stiles, H. R., 1982, Water use in Georgia by county for 1980: Georgia Geologic Survey Informa- tion Circular 59, 180 p. __1984, Georgia irrigation, 1970-80 A decade of growth: U.S. Geological Survey Water-Resources Investigations Report 83-4177, 29 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States, Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. U.S. Environmental Protection Agency, 1982a, Maximum contami- nant levels (subpart B of part 141, National interim primary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100 to 149, revised as of July 1, 1982, p. 315-318. __1982b, Secondary maximum contaminant levels (section 143.3 of part 143, National secondary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100 to 149, revised as of July 1,1982, p. 374. Wait, R. L., 1960, Source and quality of water in southwestern Georgia: Georgia Geological Survey Information Circular 18, 74 P- Wait, R. L., and Gregg, D. O., 1973, Hydrology and chloride contamination of the principal artesian aquifer in Glynn County, Georgia: Georgia Geological Survey Hydrologic Report 1, 93 p. Prepared by John S. Clarke and Robert R. Pierce For further information contact District Chief, U.S. Geological Survey, 6481 Peachtree Industrial Blvd., Suite B, Doraville, GA 30360 U.S. Geological Survey Water-Supply Paper 2275 HAWAII Ground-Water Resources National Water Summary Hawaii 185 Table 1. Ground-water facts for Hawaii [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] Population served by ground water, 1980 Hawaii has an abundant water supply, and ground water is an important natural resource that contributes significantly to the economic growth of the State. The total amount of water withdrawn in Hawaii in 1980 was 1.7 billion gallons per day of which 710 million gallons per day (Mgal/d) or 41 percent was from ground-water sources. Statewide, Maui was the largest user of fresh ground and surface water, with a total Number (thousands) - ------------------ 920 of 586 Mgal/d. Oahu was the principal user of ground water Percentage of total population -------------- 95 *% . K & From public water-supply systems: with 193 Mgal/d. For domestic use, Oahu led in ground-water Number (thousands) - ---------------- 890 usage with 173 Mgal/d (Nakahara, 1984). Ground-water Percentage of total population- ------------ 92 withdrawals in 1980 for various uses in the State are given in From rural self-supplied systems: , . Number (thousands) ----------------- 30 table 1. Percentage of total population- ------------- 3 Freshwater withdrawals, 1980 GENERAL SETTING Surface water and ground water, total (Mgal/d) ------ 1,700 Ground water only (Mgal/d) --------------- 710 The islands of the Hawaiian Archipelago occupy a 6,450 Percentage of total- ----------------- 41 square-mile land area. The Hawaiian Islands are the tops of ^hermoe^ctTic^eT^^ wkhdrawals f°r 37 shield volcanoes that rise from the ocean floor; the oldest is ermoe ec ric power Kauai and the youngest is the island of Hawaii. _____________Category of use_____________ Rainfall is the sole source of freshwater and its quantity Public-supply withdrawals: and spatial distribution govern the volume and quality of the ^^Sffiround waKr-' .' -' '- '- '- '- '- '- '- '- '- '5 ground water. Mean annual rainfall in Hawaii is about 73 Percentage of total public supply- ----------- 90 inches (in.) and ranges from about 20 to 300 in. Ground- Per capita (gal/d) ------------------ 202 water recharge is estimated to be 30 percent of rainfall RurD0s^PePjfcwithdrawals: (Takasaki, 1978). Fresh ground water in Hawaii is present as Ground water (Mgal/d) - -------------- 3.5 basal water in unconfined aquifers or in aquifers confined by Percentage of total ground water - ---------- o.5 coastal caprock under artesian pressure. Smaller amounts of Percentage of total rural domestic ---------- 90 . j , , . , , ,., , . . Per capita (gal/d) ----------------- 117 water are impounded by impermeable dike systems at higher Livestock: elevations and occur in isolated ground-water bodies perched Ground water (Mgal/d)- -------------- 5.3 on top of impermeable lava beds. Basal ground water is Percentage of total ground water - ---------- 07 , , , , . . , ... , , . .. , , - , Percentage of total livestock- ------------ 96 developed by vertical drilled wells, by inclined shafts that industrial self-supplied withdrawals: intersect the basal water, and by dug wells along coasts. Ground water (Mgal/d)- --------------- 140 Percentage of total ground water - ----------- 20 Percentage of total industrial self-supplied: Including withdrawals for thermoelectric power - - - - 73 PRINCIPAL AQUIFERS Excluding withdrawals for thermoelectric power - - - - 20 Hydrographic areas established in 1959 by the Hawaii '"'^u^^al/d)- --------------- 370 Water Authority (now the State Department of Land and Percentage of total ground water- ----------- 53 Natural Resources, Division of Water and Land Management) Percentage of total irrigation ------------- 93 are used to describe the principal aquifers on four of the major islands Kauai, Oahu, Maui, and Hawaii (Hawaii State Wa- ter Authority, 1959). The boundaries of these areas are based clay and calcareous material. Ground water occurs as basal on surface topography and outline the major surface drainage and perched water in the Koloa lavas and generally is uncon- basins (fig. 1). Aquifers of the six principal islands (including fined except where the lavas are overlain by sediments (Mac- Molokai and Lanai) are listed in table 2. donald and others, 1960). Area V, located in the western part of Kauai (fig. I A), is the most prominent basal water body underlying the Kekaha- ISLAND OF KAUAI Mana coastal plain and is composed mostly of the Napali Ground-water sources in hydrographic areas I through IV lavas. The coastal plain is composed of lagoon deposits, (fig. \A) on Kauai are used primarily for public supply and calcareous beach and dune sand, and alluvium. Coastal irrigation of sugarcane. Posterosional lavas of the Koloa, sediments are about 500 feet (ft) thick at the coast. Recharge Olokele, and Makaweli Volcanics overlie lavas of the Napali to the basalt aquifer is from rainfall, and recharge to the Formation in these areas. The coastal sediments are of limited caprock aquifer is mainly from rainfall and return irrigation extent and are composed of poorly sorted alluvium mixed with water. Individual wells or shafts yield as much as 22 Mgal/d. 186 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Hawaii [Ft = feet; gal/min = gallons per minute; Mgal/d = million gallons per day. Sources: Reports of the U.S. Geological Survey and various agencies of the State of Hawaii] Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Kauai: Koloa Volcanics: Massive posterosional lava flows and breccia mixed with sediments. Unconfined. Olokele, Makaweli, and Napali Volcanics: Basalt, alluvium, and calcareous dune sands in broad sedimentary coastal plains. Partly confined. Oahu: Alluvium: Consolidated deposits of conglomerate and breccia. Partly confined. Honolulu Group: Basalt, post-erosional lava flows; coral, reef and beach-sand deposits along coastal margins. Alluvium in stream channels. Partly confined. Koolau Volcanics: Basalt and sediment deposits of coralline limestone and sand along coast areas and alluvium. Partly confined. Waianae Volcanics: Basalt, breccia, and intercalated soils. Sediments consist of coralline limestone; terrestial material is alluvium. Partly confined. Maui: Hana Group: Posterosional lava flows primarily olivine basalt and rare feldspar phenocrysts. Unconfined. Kula Formation: Overlies the Honomanu Volcanics; large part of isthmus consists of sedimentary deposits of coralline limestone, sand dunes, and alluvium. Partly confined. Honolua and Wailuku Volcanics: Mainly thin bedded basaltic lava flows; andesite and sedimentary material of coralline limestone, sand, and alluvium near southern shorelines. Unconfined. Hawaii: Puna Volcanics: Basaltic lava flows overlying the Hilina Volcanic; vitric ash and tuff beds intrastratified with the lava. Unconfined. Laupahoehoe Volcanics: Posterosional andesitic lava flows. Unconfined. Hualalai Volcanics: Volcanic posterosional trachyte and basalt with vitric ash overlying lava flows. Unconfined. 100-1,100 100-500 100 - 400 2,000 Low to moderate permeability. Discontinuous perched water body at high levels, basal water below sea level. 200 - 1,900 8,000 Moderate to high permeability. Important source for domestic and irrigation water. Brackish water in coastal plains. 30-900 100-1,100 100-1,100 40-600 90-500 200-500 200-500 400-2,300 9,000 700-6,000 13,000 600-4,000 12,000 Low to moderate permeability. Found in stream channels and marine sediments. Low to high permeability. Important source of domestic supply for city of Honolulu. Withdrawal of ground water managed under Ground-Water Use Act. Moderate to high permeability. Area IV is commonly called the Pearl Harbor aquifer. Principal source of ground water for domestic and irrigation supply. Aquifer managed under Ground-Water Use Act. 70-2,300 9,000 Low to moderate permeability. Water confined near sea level and at high levels in dike complex. Withdrawal of ground water in Area VI managed under Ground-Water Use Act. 40 - 60 80 Moderate to high permeability. Primary source of domestic and irrigation supply. 500 - 6,000 8,000 High permeability in dike-free area. Low to moderate permeability in sediment deposits. Important water source for domestic supply and irrigation of sugarcane. 120-1,600 8,000 Moderate permeability; yields water to wells freely. Waikapu Shaft has yielded an average of 23 Mgal/d (1957-81). Important water source for irrigation of sugarcane and domestic supply. 20-800 500-2,500 7,000 Lava flows highly permeable. Important source of domestic supply for City of Hilo. 100-900 Poor to moderate permeability. No data available. 150-600 3,000 Basalt is highly permeable. Important source of domestic water for tourist industry in Kona. A KAUAI NW 15000' 10000' 5000'H WAIPIO VALLE. Sea level National Water Summary Hawaii 187 D HAWAII EXPLANATION [ | | | | | [ | [ j [ ] SE Hydrographic areas ALL ISLANDS Sedimentary material KAUAI Koloa, Olokele, and Makaweli volcanics Lavas of Napali OAHU Alluvium Koolau volcanics Honolulu Group and Waianae volcanics MAUI Kula, Wailuku, and Honomanu volcanics Hana Group and Honolua volcanics HAWAII Puna, Hualalai, Kahuku, and Hamakua volcanics Kau, Hilina, and Polulu volcanics Laupahoehoe, Hawi, and Ninole volcanics 157° MOLOKAI ./^^*>v. I LANAI VJ^TVIAUI <3> KAHOOLAWE Figure 1. Principal aquifers in Hawaii (inset map shows actual relative location of islands). A, Kauai. B, Oahu. C, Maui. D, Hawaii. (See table 2 for a more detailed description of the aquifers. Sources: Stearns and Macdonald, 1942; modified after Takasaki, 1978.) 188 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Hawaii Continued Aquifer name and description Well characteristics Depth (ft) uommon range Yield (gal/min) Common Remarks range May exceed Kau Volcanics: Basaltic lava 300 - 1,000 400 - 1,500 flows overlying the Kahuka and Ninole Volcanics; vitric ash and tuff beds interstratified with the lava. Unconfined. Hamakua Volcanics: Primarily 200-800 200-1,300 basaltic lava flows capped by Pahalaash. Unconfined. Hawi Volcanics: Posterosional lava flows of oligoclase andesites. Unconfined. Pololu Volcanics: Primarily 30-800 100-900 thin-bedded olivine basalt interbedded with a few vitric tuff beds. Unconfined. Molokai: East Molokai Volcanics, upper member: 80 - 1,100 50-200 Lava flows composed chiefly of dense andesites and trachyte. Unconfined. Lanai: Lanai Volcanics: Primarily 60 -1,200 80-150 basaltic lava flows with small amounts of pyroclastic material. Unconfined. 2,500 Basalts are highly permeable. Brackish water along coast. Water mainly used for irrigation and processing of sugarcane. 3,800 Moderate to high permeability. Yields basal water freely to wells and springs. Poor permeability. No well data available. 4,100 High permeability. Yields water to wells freely. 500 Low to moderate permeability. Primary source of domestic supply. 200 Moderate to high permeability. Primary source of domestic and irrigation supply. ISLAND OF OAHU The island of Oahu is the weathered and eroded remnant of two major coalescing shield volcanoes the Waianae and Koolau. The Koolau volcanics are highly permeable and yield water to wells freely. The Waianae Volcanics have low to moderate permeability. Hydrographic areas II to IV and VI on Oahu (fig. IB) are important sources of ground water; the chemical quality of ground water in these areas is discussed by Swain (1973). Areas I and II include the northeastern and southeastern parts of windward Oahu and are composed almost entirely of the dike complex of the Koolau Range with thick alluvium and caprock. Ground water is primarily dike impounded. Basal water is present in calcareous sedimentary materials at the southern end. Where ground water is confined by caprock or alluvium, water flows in the upper aquifer and discharges to streams (Takasaki and others, 1969). The city of Honolulu and a part of southeastern Oahu are included in Area III. The area is underlain primarily by thin-bedded basalts of the Koolau Volcanics and posterosional flows of the Honolulu Group. Near the coast, an extensive caprock confines the basal aquifers. Ground water is present as thick basal lenses in the highly permeable Koolau lavas, and dike-impounded water is present at high elevations (Stearns, 1939). The aquifer in this area commonly is called the Honolulu aquifer. Area IV of central Oahu, includes large rainfall zones of the Koolau Range. Koolau lavas predominate in the area. The coastal plain in the southern section of the area is underlain by thick caprock that confines basal ground water. Basal ground water is present in caprock, alluvium, and dikes near the Koolau Crest and in much of the Waianae Volcanics (Visher and Mink, 1964). These rocks are known as the Pearl Harbor aquifer, which is the principal and most productive aquifer on Oahu. Recharge to the aquifer is by direct infiltra- tion of rainfall and irrigation return water and by underflow from the Koolau dike compartments, the Schofield high-level water body, and the Honolulu area (Hawaii State Department of Land and Natural Resources, 1979). Area V, in the western part of the Waianae Range, is comprised chiefly of dike-intruded basalt of the Waianae Volcanic Series. Dike impoundments are the principal source of ground water. Area VI, in the northwestern section of Oahu, includes part of the Schofield Plateau and the mountainous parts of the Waianae and Koolau Ranges. The principal basal aquifer is in the thin-bedded basalts of the Koolau Volcanics. A thick wedge of caprock occurs at the northern part of the area and confines water at hydraulic heads of 2 to 20 ft above sea level. Ground water in the Schofield Plateau contributes large volumes of underflow to this area and to Area IV to the south (Rosenau and others, 1971). ISLANDS OF MOLOKAI AND LANAI The upper member of the East Molokai Volcamcs is the principal source of ground water on Molokai. It covers most of the island and is composed of dense andesites and trachytes (Stearns, 1947). Concentrations of chloride in basal water underlying coastal areas range from 600 to 1,000 milligrams per liter (mg/L). National Water Summary Hawaii 189 HJ 2 0 oc _J 10 3s 20 <» 30 Sg B 50 4 Napali volcanics aquifer Confined *~~vv~~ ~- - 1945 1955 1965 1975 1985 1 0 £ WATER IEVEL, OR BELOW LAND SI U M -. 000 g 40 tu 50 LL. 6 Koolau volcanics aquifer Confined ; ^^- - - 1955 11 Kula volcanics aquifer Unconfined 1975 200 15 Puna volcanics aquifer Unconfined Kauai Maui EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) O Less than 5 O 5.0-26 © 25.1 - 50 Q Greater than 50 Location number 2 O Withdrawal site Kahoolawe 1945 1955 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Geographic area Wailua, Kapaa areas, Kauai. Koioa, Lawai areas. Kauai. Mana, Kekaha areas, Kauai. Waiaiua area, Oahu . . Central Oahu area. . . Honolulu area, Oahu. Koolaupoko area, Oahu. Island of Molokai . . . West Maui area .... Central Maui area . . . Island of Lanai .... Kona area, Hawaii. . . Pahala area, Hawaii . . Olaa, Puna, Kapoho areas, Hawaii. Hilo area, Hawaii . . . Laupahoehoe area. Hawaii. Aquifer Koloa volcanics .... ... .do ......... ... .do ......... Napali volcanics. . . . Waianae volcanics. . . Koolau volcanics . . . ... .do ......... ... .do ......... East Molokai vol- canics, upper member. Honolua volcanics. . . Lanal volcanics .... Huaialai volcanics. . . Hamahua volcanics . . Principel uses Public supply. Public supply. Industrial. Public supply. Irrigation, public supply. Irrigation, public supply, industrial. Do. Public supply, industrial. Public supply. Irrigation, public supply. Do. Do. Do. Public supply. Irrigation, industrial. Public supply, irrigation. Public supply, industrial. Public supply, irrigation. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Hawaii. (Sources: Withdrawal data from Nakahara, 1984; water-level data from U.S. Geological Survey files.) 190 National Water Summary Ground-Water Resources Lanai is composed primarily of basaltic lava flows from the Lanai Volcanics. The basal water along the coast is brackish. Ground water in the basaltic lava is confined by intrusive rocks and is the main source of potable water for the island. The water is of excellent quality with an average chloride content of 22 mg/L (Stearns, 1940b). ISLAND OF MAUI The island of Maui is formed by two volcanoes, Haleaka- la (East Maui) and West Maui. The isthmus connecting the two volcanoes is covered by terrestrial sediments, dune sands, and beach deposits. The bulk of the two volcanoes consists of very permeable basaltic lava flows. Hydrographic areas I through III (fig. 1C) are significant sources of ground water. The western one-half of West Maui forms Area I. The thin-bedded, very permeable primary basalts of the Wailuku Volcanics and the massive and less permeable basalts of the Honolua volcanics comprise most of the aquifer. Basal ground water that exists along the coastal area extends inland from 1 to 3 miles (mi) and is the principal source of ground water. The principal source of drinking water is a narrow strip 1 to 2 mi inland at elevations of 700 to 900 ft. The chloride concentration of water in wells that tap the basal aquifer ranges from 100 to 2,000 mg/L for irrigation wells and 50 to 200 mg/L for domestic wells (M. E. Ikehara, U.S. Geological Survey, written commun., 1984). Area II includes the eastern one-half of West Maui. Except for a large wedge of sedimentary material across the isthmus, it is similar geologically to Area I. Large basal water bodies are present in lava flows of the Kula Formation that underlie the isthmus. Water quality is excellent in the major basal water body and chloride concentration ranges from 10 to 50 mg/L. Water in the thin basal ground-water lens near the shoreline generally is brackish. Area III is the western slope of Haleakala and the eastern one-half of the isthmus. The surface rocks are mostly mas- sive, poorly permeable lava flows of the Kula Formation which overlies the Honomanu Volcanics. In the isthmus, the Kula lavas are overlain by alluvium and dune sands. In the northern part of the area, basal ground water is pumped intensively for irrigation of sugarcane. The chloride concen- tration of water in the basal wells ranges from 100 to 900 mg/L. Areas IV and V cover the northeastern and southern parts of Maui. The areas are geologically similar to the Hana Volcanics which veneer most of the surface. Ground water occurs mainly as basal water; chloride concentrations range from 10 to 200 mg/L in both areas. ISLAND OF HAWAII The island of Hawaii, which includes the mountains of Mauna Kea, Mauna Loa, Kohala, Hualalai and Kilauea, is formed predominantly of thin-bedded permeable basaltic lava flows. Sedimentary materials are sparse and generally are poorly permeable (Stearns and Macdonald, 1942b). Currently, areas I through IV (fig. ID) are important ground-water sources for public supply. Area I includes the northern part of the island. The principal basal aquifer consists of thin-bedded flows of the Pololu Volcanic Series occurring in coastal areas and capped by the Hawi Volcanics at higher elevations. The water quality is excellent in inland areas, but chloride concentrations near the coastline range from 1,000 to 2,000 mg/L. Area II includes the eastern part of the island and is composed of the basaltic lava flows of the Hamakua, the Ninole, and the Hilina Volcanic Series, and the posterosional lava flows of the Laupahoehoe, the Kau, and the Puna Volcanic Series. Numerous springs discharge water from perched water bodies near the surface along coastal areas. Ground water is fresh in inland areas and probably contains less than 1,000 mg/L of chloride near the shoreline. Area III is the southeastern section of the island of Hawaii. The area contains no perennial streams despite an annual average rainfall that exceeds 125 in. Basal ground water in the Kau Volcanics discharges to the sea as spring flow. Chloride concentration of water pumped from inland wells ranges from 100 to 2,000 mg/L. Area IV is the southwestern section of the island. The principal source of fresh water is basal ground water occurring in the Hualalai Volcanic Series, which is underlain by saline water. Because of an absence of sediments at the coast, basal water discharges freely at sea level along most of the shoreline. Where water levels are more than 3 ft above sea level, chloride concentrations range from 30 to 1,200 mg/L. Area V is the driest of the hydrographic areas; no peren- nial streams exist in this area. The principal source of ground water is basal water that occurs in the Kau Volcanic Series along the coastal areas. It is used mainly for small domestic supplies. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Principal areas of ground-water withdrawal and trends in ground-water levels at selected wells on four major islands are shown in figure 2. Based on long-term pumpage records, the largest concentration of ground-water pumpage for irrigation is in hydrographic areas V on Kauai; IV and VI on Oahu, and areas I through III on Maui. The largest areas of pumping for public supply are areas II through IV on Oahu. In general, hydrographs for wells that produce water for irrigation of sugarcane reflect a slight rise in water level because of reduced pumping caused by urbanization of agricultural lands, re- placement of furrow irrigation by the more efficient overhead spray, and use of drip-irrigation methods. In contrast, in- creased withdrawals for public supplies on Kauai and Oahu have contributed to steadily declining levels since 1973. On the island of Hawaii, water levels in selected wells shown in figure 2 have been steady or risen slightly despite the dramatic growth of the population and tourist industry in the Hilo and Kona areas. The increase in water levels was due to above-average precipitation from 1973 to 1983, resulting in increased recharge. National Water Summary Hawaii 191 GROUND-WATER MANAGEMENT Comprehensive management of Hawaii's water resources is required by law under the 1978 amendment to the State Constitution (Article XI, Section 7). Two State organizations, the State Department Land and of Natural Resources (DLNR) and the State Department of Health (DOH), implement most of the regulatory and planning requirements mandated by this legislation. The DLNR administers the overall water resources development and regulates all withdrawals of water from ground-water sources. Under the 1959 Ground-Water Use Act, Hawaii Revised Statutes (HRS 177, Title 13, Chapter 166), and Regulation 9, ground-water within designated areas is subject to control by the DLNR. Ground-water control designations have been established in areas III, IV, and VI on Oahu to prevent depletion, waste, pollution, or deterioration by saltwater encroachment. Permits for drilling of wells on Oahu are required by the DLNR or the Honolulu Board of Water Supply. The DOH administers programs designed to protect the quality of ground water. The 1972 Federal Water Pollution Control Act Amendments (Public Law 92-500) are adminis- tered by the DOH in the State of Hawaii. In response to the specific requirements contained in Section 208 of the Act, the DOH developed plans for Hawaii in cooperation with other State and county departments to achieve the national, State, and county goals of preservation, restoration, and mainte- nance of water quality. The 1974 Safe Drinking Water Act (Public Law 93-523) requires the U.S. Environmental Protection Agency (USEPA) to develop minimum programs for the State to protect under- ground drinking-water sources. In response to a request from USEPA, the DOH has compiled and adopted an Underground Waste Injection Control program to meet specific hy- drogeologic settings. SELECTED REFERENCES Hurt, R. J., 1979, Availability of ground water for irrigation on the Kekaha-Mana coastal plain, island of Kauai, Hawaii: Hawaii State Department of Land and Natural Resources Report R53 (revised), 50 p. Dale, R.H., and Takasaki, K. J., 1976, Probable effects of increasing pumpage from Schofield ground-water body, island of Oahu, Hawaii: U.S. Geological Survey Water-Resources Investigations 76-47, 45 p. Hawaii State Department of Land and Natural Resources, 1979, Surface and ground-water resources: Unpublished study element report of the Water Resources Regional Study, Honolulu, Ha- waii, 431 p. Hawaii State Department of Land and Natural Resources, 1980, State water resources development plan, 1980: Honolulu, Hawaii, 165 p. Hawaii State Water Authority, 1959, Water resources in Hawaii: Hawaii Division of Water and Land Development Bulletin B14, 148 p. M and E Pacific, Incorporated, 1984, Annual report Board of Water Supply, City and County of Honolulu, 1984: Honolulu, Hawaii, 44 p. Macdonald, G. A., Davis, D.A., and Cox, D. C., 1960, Geology and groundwater resources of the island of Kauai, Hawaii: Hawaii Division of Hydrography Bulletin 13, 212 p. Nakahara, R. N., 1984, Water use in Hawaii, 1980: Hawaii State Department of Land and Natural Resources, Report R-71, 26 p. Rosenau, J. C., Lubke, E. R., and Nakahara, R. H., 1971, Water resources of north-central Oahu, Hawaii: U.S. Geological Sur- vey Water-Supply Paper 1899-D, 40 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Stearns, H. T., 1939, Geologic map and guide of Oahu, Hawaii: Hawaii Division of Hydrography Bulletin 2, 75 p. __1940a, Supplement to the geology and ground-water resources of the island of Oahu, Hawaii, with chapters by Schwartz, J. H., and Macdonald, G. A.: Hawaii Division of Hydrography Bulle- tin 5, 164 p. __1940b, Geology and ground-water resources of Lanai and Kahoo- lawe, Hawaii, with chapters by McDonald, E. A., and Swartz, J. H: Hawaii Division of Hydrography, Bulletin 6, 177 p. __1947, Geology and ground-water resources of the island of Molokai, Hawaii: Hawaii Division of Hydrography, Bulletin 11, 113 p. Stearns, H. T., and Macdonald, G. A., 1942a, Geology and ground- water resources of the island of Maui, Hawaii: Hawaii Division of Hydrography, Bulletin 7, 344 p. __1942b, Geology and ground-water resources of the island of Hawaii: Hawaii Division of Hydrography Bulletin 9, 363 p. __1942c, Geology and ground-water resources of the island of Oahu, Hawaii: Hawaii Division of Hydrography Bulletin 1, 479 P- Swain, L. A., 1973, Chemical quality of ground water in Hawaii: Hawaii State Department of Land and Natural Resources Report R48,54 p. Takasaki, K. J., 1977, Elements needed in design of a ground-water quality monitoring network in the Hawaiian Islands: U.S. Geological Survey Water-Supply Paper 2041, 23 p. __1978, Summary appraisals of the nations ground-water re- sources Hawaii Region: U.S. Geological Survey Professional Paper813-M, 27 p. Takasaki, K. J., Hirashima, G. T., and Lubke, E. R., 1969, Water resources of windward Oahu, Hawaii: U.S. Geological Survey Water-Supply Paper 1874, 59 p. Visher, F. N., and Mink, J. F., 1964, Ground-water resources in southern Oahu, Hawaii: U.S. Geological Survey Water-Supply Paper 1778,133 p. Prepared by Santos Valenciano For further information contact District Chief, U.S. Geological Survey, P. O. Box 50166, Honolulu, HI 96850 192 National Water Summary Ground-Water Resources U.S. Geological Survey Water-Supply Paper 2275 IDAHO Ground-Water Resources National Water Summary Idaho 193 Table 1. Ground-water facts for Idaho [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] Population served by ground water, 1980 Although intensive use of ground water for agriculture has lowered water levels significantly in some areas of Idaho, the State's overall ground-water resources barely have been tapped (Idaho State, 1972). In 1980, about 88 percent of the people in Idaho depended on ground water for domestic supply; however, withdrawals for public and rural domestic supplies amounted to only about 3 percent of the 6.3 billion Number (thousands) - ------------------ 827 gallons per day (bgd) of total ground-water withdrawals. Percentage of total population -------------- 88 ^ , . , j . . __~, . . From public water-supply systems: Ground-water withdrawals in 1980 for major use categories Number (thousands) ----------------- 592 are given in table 1. Percentage of total population ------------- 63 By far the largest use of ground water in the State is From rural self-supplied systems: . . . , . , . . nor. , xi , . j /- j Number (thousands) ----------------- 235 irrigated agriculture. In 1980, about 4.1 bgd of ground water, Percentage of total population - ------------ 25 or about 65 percent of total ground-water withdrawals, was r. . . .... . 400n , . . . , , , Freshwater withdrawals, 1980 pumped for irrigation. In 1980, about 2.1 bgd of ground j n j .. , -1JJ- ^ i- Surface water and ground water, total (Mgal/d) ----- 18,000 water was used for industrial purposes; included in this total is Ground water only (Mgal/d) ------------- 6^00 ground water discharged from springs and used in the many Percentage of total- ----------------- 35 aquaculture operations along the Snake River in southern Percentage of total excluding withdrawals for Idaho thermoelectric power ---------------- 35 Category of use Public-supply withdrawals: Ground water (Mgal/d)- --------------- 150 GENERAL SETTING Percentage of total ground water- ------------ 2 Idaho encompasses parts of four physiographic provinces P^^£^ ^ ^l - - - - - - - - - - - 2?3 (fig. 1). The Columbia Plateaus province is located primarily Rural-supply withdrawals: in Oregon and Washington but extends into southern Idaho. Domestic: Most of the Columbia Plateaus in Idaho consists of the Ground water (Mgal/d)- - - - --------- 44 Percentage of total ground water- ---------- 0.7 15,600-square mile Snake River Plain, which extends across Percentage of total rural domestic ---------- 96 southern Idaho and is underlain in part by one of the most Per capita (gal/d) ----------------- 187 productive aquifers in the United States the Snake Plain Livestock: n . ,. , ^ . ^ , .- Ground water (Mgal/d) - -------------- 9.3 aquifer. Most of the State north of the Snake River Plain is in Percentage of total ground water- ---------- o.l the Northern Rocky Mountains province, which is underlain Percentage of total livestock- ------------ 42 principally by granitic rocks. In general, the granitic rocks Industrial self-supplied withdrawals: ,, , . - ,. ^. > ._,_,, Ground water (Mgal/d)- -------------- 2,100 yield only small quantities of water to wells. The Middle Percentage of total ground water- ----------- 33 Rocky Mountains province includes the mountains of eastern Percentage of total industrial self-supplied: Idaho, the southernmost of which form the northern drainage Including withdrawals for thermoelectric power - - - - 95 of the Bear River, which flows into Utah. A small part of the irrigatfo^Sat^315 ** therm°dectric P°Wer ' ' ' ' 95 Basin and Range province extends northward into southern Ground water (Mgal/d)- -------------- 4,100 Idaho and drains to the Bear River and Great Salt Lake in Percentage of total ground water - ----------- 65 Utah Percentage of total irrigation ------------- 25 Precipitation is affected by topography and varies widely throughout the State; the annual range is from about 10 inches (in.) on most of the Snake River Plain to 20 or 30 in. in the surrounding highlands. Ground-water recharge from precipi- PRINCIPAL AQUIFERS tation on the Snake River Plain is 2 to 5 percent of the total Although 70 aquifers have been identified in Idaho precipitation (Kjelstrom, 1984). Over most of the central (Graham and Campbell, 1981), many are limited in extent and mountains, annual precipitation commonly is 40 to 50 in. but yield insignificant amounts of water. Three principal aquifers may exceed 60 in. in some areas. Most precipitation falls in or groups of aquifers in Idaho are identified in figure 1 and are the winter as snow. described below and in table 2. 194 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Idaho [Gal/min = gallons per minute; ft = feet; °F = degrees Fahrenheit. Sources: Reports of the U. S. Geological Survey and Idaho state agencies] Well characteristics Aquifer name and description Depth, common range (ft) Yield (gal/min) Remarks Common range May exceed Valley-fill aquifers: Intermontane valley fill and alluvium. Chiefly unconsolidated gravel, sand, silt, and clay. Primarily glacial outwash, locally interbedded with basalt and rhyolite in north Idaho. Generally unconfined. Basalt aquifers: Mostly olivine basalt with thin, interbedded layers of gravel, sand, silt, and clay. Confined and unconfined. Sedimentary and volcanic aquifers: Unconsolidated fine sand, silt, and clay with basalt and felsic rocks and interbedded shale and sandstone. Confined and unconfined. 20-700 2-2,000 3,500 Sedimentary rocks of Salt Lake Formation are important aquifers in some southeastern river valleys. Spokane Valley-Rathdrum Prairie aquifer in north Idaho supplies some water to city of Coeur d'Alene. Locally, concentrations of dissolved solids, nitrate plus nitrite, iron and cadmium may exceed national drinking-water regulations. 100-1,000 300-3,300 7,000 Chiefly basalts of the Snake River Group in southeast Idaho and basalts of the Columbia River Basalt Group in east-central and north Idaho. Snake Plain aquifer is principal aquifer in State and supplies water for irrigation and most domestic and industrial uses in eastern Snake River Plain. Well yields variable. Concentrations of nitrate plus nitrite and dissolved solids may exceed national drinking-water regula- tions. In northern Idaho, wells in basalt aquifers supply water to cities of Lewiston, Moscow, and Grangeville. Thermal ground water near 100°F is pervasive in Twin Falls County. 50-3,000 100-2,500 3,000 Most important aquifers in Boise Valley are in alluvial sands and gravels; depth to water commonly less than 25 ft in many areas, and drainage a problem locally. Aquifers in sediments and basalts of Idaho Group supply water to cities of Boise, Nampa, and Caldwell. Deep wells completed in silicic rocks of Idavada Volcanics and Banbury Basalt in Elmore and Owyhee Counties yield water between 100° and 180°F under pressures greater than atmospheric; these waters commonly have large concentrations of fluoride and sodium. Quality of water generally suitable for most agricultural and domestic uses. VALLEY-FILL AQUIFERS Unconsolidated sedimentary aquifers in intermontane valleys are grouped as valley-fill aquifers (fig. 1), which yield sufficient water to wells for most rural-domestic use and may sustain farming operations of considerable magnitude. In- cluded in this group are aquifers in drainage basins tributary to the Snake, Boise, and Bear Rivers. In the Idaho Panhandle area (northern Idaho), valley-fill aquifers consist primarily of glacial outwash unconsolidated gravel, sand, silt, and clay and some recent alluvium. Wells completed in these aquifers generally yield quantities of water suitable for domestic supplies. Dissolved-solids concentra- tions ranged from 250 to 500 milligrams per liter (mg/L), nitrate plus nitrite concentrations ranged from 0 to 25 mg/L, and iron concentrations exceeded 1.7 mg/L in one-half of the wells sampled (Parliman and others, 1980). The Spokane Valley-Rathdrum Prairie aquifer, a valley- fill aquifer in Washington and Idaho (not specifically identi- fied in fig. 1) is the main source of supply for the cities of Spokane, Wash., and Coeur d'Alene, Idaho. In Idaho, the aquifer consists chiefly of glacial outwash a mixture of unconsolidated silt, sand, gravel, and boulders. Wells comp- leted in this aquifer generally are less than 200 feet (ft) deep and are used primarily for irrigation supply. They commonly yield large quantities of water with little drawdown because of exceptionally large aquifer transmissivity. Locally, concentra- tions of dissolved iron in the water may exceed 0.2 mg/L (Parliman and others, 1980). BASALT AQUIFERS Numerous basalt flows and thin, interbedded sediments of the Snake River Group comprise the Snake Plain aquifer, which is the principal aquifer in Idaho. The aquifer supplies water for most domestic and industrial uses on the Snake River Plain upstream from King Hill. The greatest use of the water, however, is for irrigation (fig. 2); in 1980, about 1,720 Mgal/d of water was withdrawn from the Snake Plain aquifer to irrigate about 900,000 acres of farmland. The aquifer discharges about 6,000 cubic feet per second (ftVsec) to the Snake River, largely from a series of springs between Milner and King Hill that issue from the northern wall of the Snake River canyon (Kjelstrom, 1984). Spring flow accounts for National Water Summary Idaho 195 49'-.. EXPLANATION A. NORTHERN ROCKY MOUNTAINS B. COLUMBIA PLATEAUS C. MIDDLE ROCKY MOUNTAINS D. BASIN AND RANGE PROVINCE r^ *;s-cr./*- 48 Snake - ___ 'iver -----._. Water _.table.-- - ^^si A \- 6000 -i LU-I UJUJ EXPLANATION Valley-fill aquifers Basalt aquifers Sedimentary and volcanic aquifers Not a principal aquifer A A'Trace of cross section 100 MILES 50 Figure 1. Principal aquifers in Idaho. A, Geographic distribution. B, Physiographic diagram and divisions. C, Generalized cross section (A-A'). (See table 2 for a more detailed description of aquifers. Sources: A, Graham and Campbell, 1981. B, Fenneman, 1931; Raisz, 1954. C, Whitehead, 1984.) 196 National Water Summary Ground-Water Resources nearly 56 percent of mean annual flow in the Snake River at King Hill and for about 75 percent of the flow at that site during July and August when flows are at a minimum because of upstream diversions for irrigation. Urbanization, return of excess irrigation water to the aquifer through drain wells, and infiltration of industrial effluents have caused local deteriora- tion of water quality in the aquifer. Generally, however, the quality of water is suitable for most agricultural and domestic uses. Locally in Twin Falls County, some wells completed in basalt yield geothermal water having temperatures of 86° to 160°F; the heated water is used for space heating, greenhouse operation, and agriculture. In the Moscow-Lewiston area, basalt aquifers are inter- calated with gravel, sand, and clay. Principal aquifers are in volcanic rocks of the Columbia River Basalt Group and fine-grained sediments of the Latah Formation. These aqui- fers supply the cities of Lewiston, Moscow, and Grangeville and, although well yields are mostly small to moderate, wells are pumped extensively for irrigation of wheat and barley. In the Weiser River basin in western Idaho, aquifers in basalts of the Columbia River Basalt Group supply water for irrigation and rural domestic use and for the cities of Council, Cambridge, and Midvale. SEDIMENTARY AND VOLCANIC AQUIFERS Sedimentary and volcanic aquifers of the western Snake River Plain are composed of gravel, sand, silt, and clay interbedded with basalt, shale, and sandstone; water from these aquifers is used chiefly for irrigation. South of the Snake River in Owyhee County, wells as deep as 3,600 ft that tap interbedded volcanic and sedimentary rocks produce geother- mal water at temperatures ranging from 90° to 183°F with artesian heads above land surface. Although the concentra- tions are typically large in fluoride (as much as 27 mg/L), and in sodium (as much as 140 mg/L), the geothermal water, when cooled, is used for irrigation of alfalfa. Sedimentary and volcanic aquifers in the Mountain Home area are composed of basalt interbedded with poorly consolidated to unconsolidated gravel, sand, silt, and clay. Well yields are extremely variable. Water levels in some wells have declined markedly in the last 15 years in response to pumping for irrigation (location 6, fig. 2). Consequently, part of the area has been designated a Critical Ground-Water Area (see Ground-Water Management section). These aquifers are the principal source of water for the city of Mountain Home and for the Mountain Home Air Force Base. Locally, concen- trations of nitrate and dissolved solids in ground water may exceed national drinking-water regulations established for public water supplies. In the Boise Valley area, sedimentary and volcanic aqui- fers are composed chiefly of unconsolidated clay, silt, sand, and gravel with interbedded basalt. Most shallow aquifers are alluvial sands and gravels; deep aquifers are sediments and basalts of the older Idaho Group. These aquifers are used extensively for irrigation and for domestic and industrial supply for the cities of Boise, Nampa, and Caldwell. The quality of the water generally is suitable for most agricultural and domestic uses. Aquifers in the Cottonwood-Oakley Fan area are com- posed of rhyolite, basalt, limestone, and unconsolidated sand and gravel. Water from the aquifers is used primarily for irrigation. Extensive pumping, particularly from volcanic rock aquifers, has lowered water levels as much as 50 ft between 1973 and 1983 (location 12, fig. 2). As a result, several Critical Ground-Water Areas have been designated in this area. Limited water-quality data indicate that the ground water is suitable for irrigation and domestic use. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Distribution of ground-water withdrawals and water-level trends in the State are shown in figure 2. Nearly three-fourths of the State's population is located in southern Idaho on the Snake River Plain, and about 3.1 million acres of farmland were irrigated on the plain in 1980 (Bigelow and others, 1984). Consequently, most of the water use and associated water- level declines are in the southern part of the State. Use of water from the Snake River and its tributaries for irrigation on the plain began in about 1840 and increased considerably in the 1880's. By 1899, about 550,000 acres on the Snake River Plain were irrigated (Lindholm and Goodell, 1984). After 1900, dams constructed on the Snake River supplied additional water for irrigation and, by 1929, irrigated acreage on the plain had expanded to 2.2 million acres (Lind- holm and Goodell, 1984). Since the late 1940's, most surface- water supplies have been appropriated, and use of ground water for irrigation has increased. In 1980, about 2.1 million acres on the Snake River Plain were irrigated with surface water, largely by gravity diversions from the Snake and Boise Rivers. One million acres were irrigated with about 2 bgd of ground water withdrawn from about 5,300 wells (Bigelow and others, 1984). With virtually all surface water on the Snake River Plain already appropriat- ed, water for irrigation will be withdrawn from ground-water supplies if additional lands are developed for farming. Water levels in wells on the Snake River Plain have been greatly affected by changes in irrigation practices over the years which include decreased use of surface water, increased use of ground water, and conversion to more efficient sprin- kler irrigation systems. Recharge resulting from the applica- tion of large quantities of surface water for irrigation raised ground-water levels a few to several tens of feet over wide areas of the Snake River Plain. The rise in water levels resulted in increased spring discharge, particularly between 1910 and 1950, during which time spring discharge increased by about 1.9 bgd. Since 1950, ground-water levels and spring discharges generally have declined, partly because of increased use of ground water for irrigation (fig. 2). Net water-level declines between 1971 and 1982 were observed in 75 percent of 361 observation wells; declines ranged from about 1 to 53 ft. Declines from 5 to 10 ft were common across most of the Snake River Plain. Declines of more than 10 ft were most common in or near areas of intensive agricultural development, such as northern Owyhee, southern Elmore, southern Canyon, and Camas Counties. National Water Summary Idaho 197 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) 0 0 - 49 O 50 - 99 Q 100 - 499 - 2500 1965 1975 1985 1955 1 120 g 130 -» 140 3 150 t '60 £ 170 i!*o a: 200 o 59 ~ 13 Basait aquifer Unconfined - - ^^- ^^ - I I I I i i I 640 650 660 670 680 690 700 710 720 ~ 15 Basalt aquifer Unconfined - ~ ^ - - i I I I I i I to 20 30 40 50 60 70 80 90 ~ 17 Basalt aquifer Unconfined - : X^^^vv j VN/N/' 1 1 1 1 1 1 1 15 1955 1965 1975 1985 1945 1955 1965 1975 1985 1945 1955 1965 1975 1 Si WITHDRAWAL SITES on' Ge0a9rre3aPhlC A^uifer 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Idaho Panhandle ........ Rathdrum Prairie ........ Moscow-Lewiston area . . . . . Salmon River basin ....... Payette-Weiser Rivar Valleys. . Boise Valley ........... Murphy area........... Mountain Home-Bruneau area. Camas Prairie .......... Big-Little Wood River Valleys. Central Snake River Plain . . . Cottonwood-Oakley Fan area . Rupert-Burley area ....... Raft River Valley ........ American Falls-Blackfoot area. Big-Little Lost River Valleys. . Mud Lake area. ......... Henrys Fork-Teton Valleys . . Upper Snake River Valley . . . Bear River Basin. ........ Curlew Valley .......... Valley fill ......... ... .do ........... Basalt. ........... Valley fill ......... Valley fill, basalt ..... Sedimentary and volcanic ... .do ........... ... .do . . Valley fill ... .do . . Basalt. ........... Sedimentary and volcanic Basalt. ........... Valley fill ......... Basalt. ........... Valley fill ......... Basalt. ........... Valley fill ......... Basalt. ........... Valley fill ......... ... .do ........... Public supply, irrigation. Public supply, industrial, rural domastic. Industrial, public supply, irrigation. Public supply, irrigation. Do. Irrigation, public supply, industrial, rural domestic. Irrigation. Do. Do. Irrigation, public supply. Aquaculture, irrigation. Irrigation. Do. Do. Irrigation, aquaculture. Irrigation, public supply, industrial. Irrigation. Irrigation, public supply. Do. Do. Irrigation. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Idaho. (Sources: Withdrawal data from Solley and others, 1983; water-level data from U.S. Geological Survey files.) 198 National Water Summary Ground-Water Resources GROUND-WATER MANAGEMENT Management of ground-water resources and protection of the resource from waste and contamination are the responsibilities of the Idaho Department of Water Resources (IDWR) and the Idaho Water Resource Board. Protection of ground-water quality in the State is the responsibility of the Idaho Department of Health and Welfare, Division of Envi- ronment. Extensive pumping of ground water for irrigation has prompted the State to curtail additional agricultural develop- ment in some areas. Where declining ground-water levels become a concern to local water users, the State can declare an area a Ground-Water Management Area (GWMA) under Idaho Code 42-233b. In those areas, permits for new well construction must be approved by the IDWR to ensure that rights of existing water users are not affected adversely. If water levels decline at a rate that will threaten a reasonably safe supply for existing users, the State can declare the area a Critical Ground-Water Area (CGWA) under Idaho Code 42-233a. In those areas, no new well permits are issued, and ground-water withdrawals are reduced to levels determined by the IDWR. Presently, five GWMA's and eight CGWA's have been designated in the State. The Idaho Department of Water Resources and the Idaho Department of Health and Welfare are engaged in cooperative data-collection programs and interpretive studies with the U.S. Geological Survey. Data collected and results of the studies provided by this cooperative program form an infor- mation base upon which ground-water management decisions in Idaho are made. SELECTED REFERENCES Bigelow, B. B., Goodell, S. A., and Newton, G. D., 1984, Water withdrawn for irrigation in 1980 on the Snake River Plain, Idaho and eastern Oregon: U.S. Geological Survey Open-File Report 84-434 [maps]. Fenneman, N. M., 1931, Physiography of Western United States: New York, McGraw-Hill Book Co., 534 p. Graham, W. G., and Campbell, L. J., 1981, Groundwater resources of Idaho: Boise, Idaho Department of Water Resources, 100 p. Kjelstrom, L. C., 1984, Flow characteristics of the Snake River and water budget for the Snake River Plain, Idaho and eastern Oregon: U.S. Geological Survey Open-File Report 84-052 [Maps]. Lindholm, G. F., and Goodell, S. A., 1984, Irrigated acreage and other land uses on the Snake River Plain, Idaho and eastern Oregon: U.S. Geological Survey Open-File Report 84-452 [Map]. Parliman, D. J., 1982, Ground-water quality in east-central Idaho valleys: U.S. Geological Survey Open-File Report 81-1011, 55 p. __1983a, Ground-water quality in the western Snake River basin, Idaho: U.S. Geological Survey Water-Resources Investigations Report 82-4062, 94 p. __1983b, Reconnaissance of ground-water quality, eastern Snake River basin, Idaho: U.S. Geological Survey Water-Resources Investigations Report 82-4004, 100 p. Idaho State, 1972, Interim State water plan, preliminary report: Boise, Idaho Water Resource Board, 265 p. __1982, Idaho blue book, 1981-1982 edition: Boise, Office of the Secretary of State, 387 p. Parliman, D. J., Seitz, H. R., and Jones, M. L., 1980, Ground-water quality in north Idaho: U.S. Geological Survey Water-Re- sources Investigations 80-596, 34 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States, Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., and Mann, W. B. IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. U.S. Environmental Protection Agency, 1982a, Maximum contami- nant levels (subpart B of part 141, National interim primary drinking water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100 to 149, revised as of July 1, 1982, p. 315-318. __1982b, Secondary maximum contaminant levels (section 143.3 of part 143, National secondary drinking water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100 to 149, revised as of July 1, 1982, p. 374. Whitehead, R. L., 1984, Geohydrologic framework of the Snake River Plain, Idaho and eastern Oregon: U.S. Geological Survey Open-File Report 84-050 [maps]. Young, H. W., and Norvitch, R. F., 1983, Ground-water level trends in Idaho, 1971-82: U.S. Geological Survey Water-Resources Investigations Report 83-4245, 28 p. Prepared by Robert E. Lewis and Sally A. Goodell For further information contact District Chief, U.S. Geological Survey, 230 Collins Road, Boise, ID 83702 U.S. Geological Survey Water-Supply Paper 2275 ILLINOIS Ground-Water Resources National Water Summary Illinois 199 Table 1. Ground-water facts for Illinois [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Sources: Kirk and others, 1982; Solley, Chase, and Mann, 1983] Population served by ground water, 1980 Ground water is the source of water for almost 49 percent of the State's more than 11 million population. More than 980 million gallons per day (Mgal/d) of ground water was with- drawn in Illinois during 1980; about 49 percent was used for public supply and about 22 and 19 percent for industrial and rural supplies, respectively. In the northern part of the State, especially in the metropolitan areas of Chicago and Rockford, Number (thousands) - ----------------- 5,592 large quantities of water are withdrawn from glacial drift and Percentage of total population -------------- 49 From public water-supply systems: bedrock for municipal, industrial, and domestic use. Water Number (thousands) - --------------- 4,187 use in rural areas, including much of the southern two-thirds Percentage of total population - ------------ 37 of the State, is mostly from ground-water sources. Ground- From rural self-supplied systems: . , , , . . . . . ., , ~0^ Number (thousands) ---------------- 1,405 water withdrawals and related statistics for 1980 are given in Percentage of total population - ------------ 12 table lm Freshwater withdrawals, 1980 Although Chicago and its suburbs in Cook County de- ,. , ., T . ,.. , . ,. . Surface water and ground water, total (Mgal/d) ----- 18,000 pend largely on water from Lake Michigan, this area also uses Ground water only (Mgal/d) --------------- 980 more than 106 Mgal/d of ground water. Many industries Percentage of total- ------------------ 5 within the area served by Lake Michigan have private wells Percentage of total excluding withdrawals for and use ground water for processing, cooling, and standby ermoe ec ric p wer - purposes. In addition to Cook County, the counties of Du _____________Category of use_____________ Page, Grundy, Kane, Kendall, Lake, McHenry, and Will in Public-supply withdrawals: northeastern Illinois historically have been very dependent on Ground water (Mgal/d)- - -------------- 480 J J ^ Percentage of total ground water ------------ 49 ground water. Pumpage in these counties has increased Percentage of total public supply- ----------- 27 steadily from 9.2 Mgal/d in 1880 to more than 340 Mgal/d in Per capita (gal/d) ------------------ 114 1980 Rural-supply withdrawals: " , ... , Domestic: The ground-water quality in the State generally is good Ground water (Mgal/d) - -------------- 120 for most uses, although some water in the deeper aquifers has Percentage of total ground water - ---------- 12 deteriorated. Ground-water contamination is a threat in the Percentage of total rural domestic ---------- 97 northwestern corner where aquifers lie at or near the land Livestock1- & surface. Ground water (Mgal/d)- -------------- 67 Percentage of total ground water ------------ 7 GENERAL SETTING Percentage of total livestock - ------------ 100 r T... ... . . . . _ . . , , Industrial self-supplied withdrawals: Most of Illinois lies within the Central Lowland physio- Ground water (Mgal/d)- --------------- 220 graphic province (fig. 1). Small parts of southern and south- Percentage of total ground water- ----------- 22 western Illinois lie within the Coastal Plain, Interior Low Percentage of total industrial self-supplied: , , _ , _.. . _.__ . , . Including withdrawals for thermoelectric power ----- 1 Plateaus, and Ozark Plateaus provinces. Differing physiogra- Excluding withdrawals for thermoelectric power - - - - 10 phy and geologic conditions cause significant differences in Irrigation withdrawals: ground-water conditions. Ground water (Mgal/d)- --------------- 97 T - ,.1 ,. i j i_ TI Percentage of total ground water - ----------- 10 Large areas in western, south-central, and southern II- Percentage of total irrigation ------------- 100 linois are underlain by relatively thin glacial drift that is rarely more than 75 feet (ft) thick. In northern and east-central Illinois, the glacial drift is much thicker, exceeding 600 ft in some places. Large deposits of water-yielding sand and gravel are present in the drift, mostly in stream valleys or in buried PRINCIPAL AQUIFERS bedrock valleys as outwash deposits. Ground water in Illinois is obtained from unconsolidated The major sources of recharge to aquifers in Illinois are sand-and-gravel aquifers (largely glacial drift) and from un- infiltration of precipitation on outcrop areas and percolation derlying sedimentary bedrock aquifers, including sandstone, of ground water through confining units. Most recharge limestone, and dolomite. Extensive areas of sand and gravel occurs during the spring when evapotranspiration is low and and bedrock in the northern one-third and extreme southern precipitation is frequent. Average annual precipitation parts of the State yield large quantities of water. Elsewhere, (1931-60) ranged from 32 inches (in.) in the north to 48 in. in yields generally are less, except where preglacial stream valleys the southern tip of the State. Annual ground-water recharge are filled with sand and gravel or where Ordovician, Mississip- rates differ across the State, but generally ranges from about 1 pian, and Pennsylvanian bedrock provide small supplies. The in. in material with little permeability to about 8 in. in principal aquifers in Illinois are described below and in table permeable materials (Walton, 1965, p. 40-41). 2; their areal distribution is shown in figure 1. 200 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Illinois [Ft = feet;gal/min = gallons per minute. Sources: Reports of the U.S. Geological Survey and State agencies] Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Sand-and-gravel aquifers: Unconsolidated clay, silt, sand, gravel, and boulders deposited as till, out wash, lake deposits, and loess. Unconfined and confined. Pennsylvanian-Mississippian aquifer: Limestone and shale, cherty. Sandstone and coal beds. Confined. Shallow dolomite aquifer: Dolomite, fractured, silty at base; locally cherty. Unconfined and confined. Cambrian-Ordovician aquifer: Sandstone, fine- to coarse- grained; dolomite, fine grained, sandy. Confined. Mount Simon aquifer: Sandstone, coarse-grained, white, red in lower half; lenses of shale and and siltstone. Confined. 50-500 40-700 50-500 100-2,000 > 1,500-2,000 10-1,000 3,000 5-25 1,000 25-1,000 1,500 150-1,000 2,500 150-1,000 2,500 Probabilities for ground-water development range from poor to excellent. Out wash sand and gravel yield more than 1,000 gal/min to wells at places; large supplies generally obtained from permeable outwash in major valleys. Glacial aquifers used for many small water supplies. Mississippian rocks generally creviced and water yielding; dependable aquifer for small supplies in western Illinois. Pennsylvanian rocks generally unfavorable for large yields; locally, domestic and farm supplies obtained from thin limestone and sandstone beds. Some wells yield more than 1,000 gal/min; crevices and solution channels more abundant near surface. St. Peter, Ironton, and Galesville Sandstones most productive. Crevices in other dolomite and sandstone units generally yield small to large quantities of water. Generally, wells in this aquifer also open to Mount Simon aquifer. Moderate amounts of potable water obtained from upper 100 to 300 ft; total dissolved solids also increase with depth and may exceed 2,000 mg/L. Water becomes saline with depth. Permeability intermediate between that of St. Peter and Galesville Sandstones. Generally, wells in this aquifer also open to Cambrian-Ordovician aquifer. SAND-AND-GRAVEL AQUIFERS Glacial drift of Quaternary age covers about 80 percent of Illinois and ranges in thickness from about 1 to 600 ft. The only areas of the State not covered by glacial deposits are the extreme northwestern corner, a small area in the west, and the southern tip. The drift is more than 200 ft thick regionally in northeastern Illinois and as much as 600 ft thick in some of the major bedrock valleys. Sand and gravel of Tertiary and Cretaceous age form thick deposits in the southernmost coun- ties in Illinois and usually are included as unconsolidated deposits with the Quaternary sand and gravel. Well yields from sand-and-gravel aquifers range from about 10 to 1,000 gallons per minute (gal/min), depending on aquifer thickness, continuity, and permeability. The largest yields generally are obtained from glacial outwash sand and gravel in major valleys. The quality of the water from the sand-and-gravel aqui- fers is satisfactory for most uses. The dissolved-solids concen- tration generally ranges from 400 to 600 milligrams per liter (mg/L), and the chloride concentration is generally less than 20 mg/L. PENNSYLVANIAN-MISSISSIPPIAN AQUIFER Sedimentary rocks of Pennsylvanian and Mississippian age form the bedrock surface in about four-fifths of Illinois and constitute the Pennsylvanian-Mississippian aquifer. These rocks include limestone, sandstone, and shale that generally have small porosity and permeability. Most wells developed in these units yield less than 20 gal/min, which is enough to satisfy most domestic, farm, and very small munici- pal needs with water of acceptable quality. SHALLOW DOLOMITE AQUIFER The shallow dolomite aquifer includes carbonate rocks of Silurian and Late Ordovician age. The aquifer may be very productive where it is unconfined. Ground water is present in joints, fissures, and solution channels, and well yields may be as much as 1,500 gal/min. The water quality is acceptable for most uses. Dissolved-solids concentrations commonly range from about 350 to 450 mg/L and consist primarily of hard- ness-forming minerals. Median chloride concentrations range from about 5 to 30 mg/L, based on 40 years of record. CAMBRIAN-ORDOVICIAN AQUIFER The Cambrian-Ordovician aquifer consists of two pri- mary producing units the St. Peter Sandstone of Ordovician age and the Ironton and Galesville Sandstones of Cambrian age. On a regional basis, the entire sequence of Cambrian and Ordovician strata older than the Maquoketa Shale (which is a major confining unit) seems to function hydraulically as a single aquifer unit. The St. Peter Sandstone is used widely for domestic, small municipal, and small industrial water supplies. It com- monly yields as much as 100 gal/min. National Water Summary Illinois 201 88° CENTRAL j li-OWLAND i EXPLANATION Sand and gravel aquifers Pennsylvanian-Mississippian aquifers Shallow dolomite aquifer Cambrian-Ordovician aquifer ' ' SP - St. Peter IG - Ironton-Galesville ___^_____ ,j SCtHUYLEft-' ' ~ Mount Simon aquifer Precambrian basement Confining units \ \ Fault Trace of cross section t ^_,-j - ECNE j MACOUPIN^ _.__< __ _.__< __ ) f--> -- ^ - T ' ! CUMBERLAND' CLARK 4 pNTdOMERYl , ; IV r-i ^--i^^^^-V ' ^"" T ' " i x EFF^M k' ^^ } , \ i -ICRAWFOR& Beiiev-ius I _^fl ,f__*"ivi ° j , i w i' 3: - ST bLAIR^j^--'*''' 1 " , WAY NET i «f | /» \ ^ r !. ' i ( > t *r / 5 s*r ^^-j^^i^J^.-J' ^-J - ( Figure 1. Principal aquifers in Illinois. A Geographic distribution. B, Physiographic diagram and divisions. C, Generalized cross section (A-A 1). (See table 2 for a more detailed description of the aquifers. Sources: A, Willman and others, 1967. B, Leighton and others, 1948; Raisz, 1954. C, Compiled by M. G. Sherrill from U.S. Geological Survey files.) 202 National Water Summary Ground-Water Resources The Ironton and Galesville Sandstones form the most productive unit in the Cambrian-Ordovician aquifer and yield nearly 50 percent of the aquifer's total production. Yields of more than 500 gal/min are common in northern Illinois. Water quality in this aquifer generally is suitable for most uses. The dissolved-solids concentration ranges from less than 400 mg/L in the north to more than 1,000 mg/L in the south, where these units are overlain by progressively thicker and younger bedrock units. MOUNT SIMON AQUIFER The Mount Simon aquifer collectively includes Cambrian sandstone of the lower Eau Claire Sandstone and the Mount Simon Sandstone, which are hydraulically connected. The medium- to coarse-grained parts of this aquifer yield moderate to large quantities of water with a quality similar to that of the overlying Cambrian-Ordovician aquifer. Commonly, wells are constructed to penetrate only the upper few hundred feet because water is highly mineralized below that depth. Because of the confining nature of the Eau Claire Sandstone and heavy pumpage in the Ironton and Galesville Sandstones, hydrostat- ic heads are usually higher in the Mount Simon aquifer than in the shallower bedrock aquifers. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Kirk and others (1982, p. 6-7) described nine water-use regions in Illinois. These regions are shown in figure 2. The distribution of major ground-water withdrawal areas and trends of ground-water levels near selected pumping centers are shown in figure 2. The largest total withdrawals are near the city of Rockford (locations 1 and 2, fig. 2) in Region A and in the Chicago metropolitan area (Region B, locations 3, 4, and 5, fig. 2). Pumpage exceeds 50 Mgal/d from the sand- and-gravel and the Cambrian-Ordovician aquifers in both these areas. Water levels generally decline in response to increases in pumping and they recover as pumping is reduced. The hydro- graphs in figure 2 show the response of aquifers to pumpage and are representative of conditions in the principal aquifers at selected pumping centers in Illinois. Increased pumping in the Chicago region has created a corresponding decline in water levels in the shallow dolomite aquifer and especially in the Cambrian-Ordovician aquifer. As a result, water levels in some wells that tap the Cambrian-Ordovician aquifer have declined more than 850 ft. In the East St. Louis area, withdrawals are primarily from the sand-and-gravel aquifer, and water levels are affect- ed greatly by changes in pumpage, precipitation, and Missis- sippi River stage (location 11, fig. 2). Increased withdrawals for industrial and public-supply use through about 1956 lowered water levels in the area. Since the mid-1960's, many water users have shifted to the Mississippi River for water supply. The resulting rise in ground-water levels has caused problems such as flooding of basements and highway under- passes. GROUND-WATER MANAGEMENT At present, no State agency in Illinois has authority to regulate directly the withdrawal of ground water statewide and withdrawal permits are not required. The Illinois Water Use Act of 1983 (Public Act 83-700) established a mechanism for identifying areas of underground water-withdrawal conflicts; procedures for resolving conflicts currently are being deve- loped. Supplementing ground-water withdrawals with surface- water sources affects ground-water consumption in the coun- ties of Lake, Cook, and Du Page. These counties must comply with Lake Michigan Order 80-4 (LMO #80-4), which was issued by the Illinois Department of Transportation, Division of Water Resources. This order sets allotments of Lake Michigan water to specific water users (Illinois Depart- ment of Transportation, 1980). Water users presently pump- ing from the Cambrian-Ordovician aquifer that begin to use an allotment of water from Lake Michigan must, under terms of the order, discontinue pumping from the aquifer within 5 years. Several State agencies have regulatory authority over activities that affect ground-water quality. The Illinois Envi- ronmental Protection Act (IEP Act) grants extensive regulato- ry powers to the Illinois Pollution Control Board. The Board is authorized to promulgate regulations to prevent groundwa- ter pollution and has the authority to act for the State with regard to establishing standards for Federal laws concerning environmental protection. The Illinois Environmental Protection Agency (IEPA) is charged with enforcing regulations of the IEP Act. The charge includes evaluation, surveillance, and inspection of discharges from contaminant sources, monitoring of environ- mental quality of public-water supplies and waste-disposal sites, some classes of subsurface waste injection, and investi- gations of violations of the regulations or permits issued thereunder. The Illinois Department of Public Health has regulatory authority over a variety of activities that can affect ground- water quality. These activities include sanitation investiga- tions and inspections of public recreational and tourist facili- ties and licensing of private sewage-disposal contractors, water-well contractors, and pump installers. The Illinois Department of Mines and Minerals has responsibilities for permitting and regulating those activities in coal mining, oil and gas exploration, and subsurface waste injection of oil and wastes, some of which might adversely affect ground-water quality. Two branches of the Illinois Department of Energy and Natural Resources are nonregulatory but have authority to study ground water; these are the Illinois State Water Survey and the Illinois State Geological Survey. These agencies are authorized to collect facts and data concerning the volume, flow, and quality of underground and surface waters of the State and to publish results of these investigations. The U.S. Geological Survey works cooperatively with these two agen- cies and with the IEP A to maintain a statewide, water-data network and to investigate the State's water resources. National Water Summary Illinois 203 1X1 U fe 10 § 20 5I 30 to 40 18 50 of| 60 % P 70 fc - 1 Cambrian-Ordovician Confined aquifer ^\ A^^N^^ "/ Missing record - - - i.i.i. 1965 1975 1985 R, FEET BELOW LAND SUfl i «t S 800 i v 3 Cambrian- - Ordovician Missing^ jf record-- ^** i , i Confined ^-/ i EXPLANATION Ground-water withdrawals. 1980 (million gallons per day) O 0.0-5 O 5.1 - 25 £) 25.1 - 50 &} 50.1 - 300 A Water-use region Location number e2 Withdrawal site 1945 1955 1965 1975 1985 UJ U 1 10 g 20 33 30 3 £ 40 t K 50 of!f 6(3 g 70 1 ~ 4 Shallow Dolomite Semi-confined and Cambrian-Ordovician aquifer \ 'vV N/\ Missing I /^v. record I/ \ I - ou 40 50 60 70 80 90 100 ~ 9 Sand and Gravel Unconfined aquifer - - Unconfined ->. . ^^A^A u 10 20 30 40 50 60 70 - 11 Sand and Gravel Unconfined aquifer _ \ .- /-^y^- ^\^/^~^^^ - - 1975 1985 1945 1975 1985 1946 1955 WITHDRAWAL SITES N°- Geographic map area Water-use region A 1 Rockford area. ............ 2 Rockford area. ............ Water-use region B 3 Chicago area .............. 4 Chicago area. ............. 5 Elgin area ............... Water-use region C 6 Quincy area ............... 7 Monmouth-Galesburg area. ...... Water-use region D 8 Havana area ............... Water-use region E 9 Champaign area . . . ....... 10 Kankakee area. ............. Water-use region F 11 East St. Louis area (Wood River) . . Water-use region G 12 Vandaiia area .............. 13 Lawrenceville area ........... 14 Centralia area . .......... Water-use region H 15 Belleville area .............. 16 Chester area ............... Water-use region 1 17 Metropolis area ............. 18 Millstone area (Pope County) . . . . . Aquifer Cambrian-Ordovician ........ Sand and gravel ........... Cambrian-Ordovicien . ....... Shallow dolomite and Cambrain- Ordovician. Sand and gravel ........... ... .do ................ Cambrain-Ordovician . ....... Sand and gravel ........... ... .do ................ Sand and gravel ........... Pennsylvanian-Mississippian .... Sand and gravel ........... Shallow dolomite .......... Sand and gravel ........... Pennsylvanian-Mississippian .... ... .do ................ Sand and gravel ........... Principal uses Public supply, rural-domestic, industrial. Do. Public supply. Do. Do. Rural-irrigation, industrial. Rural-livestock, industrial. Rural-irrigation. Public supply, rural-domestic. Public supply, rural-irrigation. Industrial, rural-domestic. Industrial, rural-livestock. Industrial, rural-irrigation. Industrial. Industrial, rural-domestic. Rural-livestock, public supply. Industrial, public supply. Industrial. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Illinois. (Sources: Withdrawal data from Kirk and others, 1982; water-level data from U. S. Geological Survey files.) 204 National Water Summary Ground-Water Resources SELECTED REFERENCES Csallany, S. C, 1966, Yields of wells in Pennsylvanian and Mississip- pian rocks in Illinois: Illinois State Water Survey Report of Investigation 55,43 p. Csallany, S. C., and Walton, W. C., 1963, Yields of shallow dolomite wells in northern Illinois: Illinois State Water Survey Report of Investigation 46, 43 p. Frost, L. R., Jr., O'Hearn, Michael, Gibb, J. P., and Sherrill, M. G., 1984, Illinois ground-water observation network A planning document for network design: U.S. Geological Survey Open- File Report 84-584. Gibb, J. P., and O'Hearn, Michael, 1980, Illinois groundwater quality data summary: Urbana, Illinois State Water Survey for Illinois Environmental Protection Agency under contract 1-47-26-84-353-00, 66 p. Illinois Department of Transportation, Division of Water Resources, 1980, In the matter of allocation of water from Lake Michigan: Opinion and Order LMO 80-40, 77 p. Kirk, J. R., Jorboe, Jacquelyn, Sanderson, E. W., Sasman, R. T., and Lonnquist, Carl, 1982, Water withdrawals in Illinois, 1980: Illinois State Water Survey Circular 152,47 p. Leighton, M. M., Ekblaw, G. E., and Horberg, C. L., 1948, Physio- graphic divisions of Illinois: Illinois State Geological Survey Report of Investigations 129, 33 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C..U.S. Geological Survey, 417 p. Sasman, R. T., Benson, C. R., Ludwigs, R. S., and Williams, T. L., 1982, Water-level trends, pumpage, and chemical quality in the Cambrian-Ordovician aquifer in Illinois, 1971-1980: Illinois State Water Survey Circular 154, 64 p. Schicht, R. J., and Moench, Alien, 1971, Projected groundwater deficiencies in northeastern Illinois, 1980-2020: Illinois State Water Survey Circular 101, 22 p. Solley, W. B., Chase, E. S., and Mann, W. B. IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Student, J. D., Piskin, Rauf, Withers, L. J., and Dickman, Jay, 1981, Aquifers of Illinois Underground sources of drinking water and non-drinking water: Urbana, Illinois Environmental Pro- tection Agency, Division of Land/Noise Pollution Control, 98 p. Suter, Max, Bergstrom, R. E., Smith, H. F., Emrich, G. H., Walton, W. C., and Larson, T. E., 1959, Preliminary report on ground- water resources of the Chicago region, Illinois: Illinois State Water Survey Cooperative Ground-Water Report 1, 89 p. Walton, W. C., 1965, Ground-water recharge and runoff in Illinois: Illinois State Water Survey Report of Investigation 48, 55 p. Walton, W. C., and Csallany, S. C., 1962, Yields of deep sandstone wells in northern Illinois: Illinois State Water Survey Report of Investigation 43, 47 p. Willman, H. B., Frye, J. C., Simon, J. A., Clegg, K. E., Swann, D. H., Atherton, Elwood, Collinson, Charles, Lineback, J. A., and Buschbach, T. C., 1967, Geologic map of Illinois: Illinois State Geological Survey, map. Withers, L. J., Pisken, Rauf, and Student, J. D., 1981, Ground water level changes and demographic analysis of ground water: Ur- bana, Illinois, Environmental Protection Agency, Division of Land/Noise Pollution Control, 41 p. Prepared by Marvin G. Sherrill, Timothy R. Lazaro, and Laura L. Harbison For further information contact District Chief,U.S. Geological Survey, Champaign County Bank Plaza, 102 E. Main Street, Urbana, IL 61801 U.S. Geological Survey Water-Supply Paper 2275 INDIANA Ground-Water Resources National Water Summary Indiana 205 Table 1. Ground-water facts for Indiana [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Clark, 1980; Solley, Chase, and Mann, 1983]____________________ Population served by ground water, 1980 Ground water provides drinking water to about one-third of the people in Indiana. Virtually all water used by industry, excluding the steel and petrochemical withdrawals from Lake Michigan and cooling water for electric power generation, is ground water. Irrigation also is a major use of ground water in the State, withdrawals being roughly equal to the quantity Number (thousands) - ----------------- 1,732 of ground water withdrawn for public supply. Ground-water Percentage of total population ------.-------' 32 withdrawals in 1980 for various uses and other related statis- From public water-supply systems : tics for Indiana are given in table 1. Number (thousands) - --------------- 1,548 Percentage of total population- ------------ 28 From rural self-supplied systems: nPMPRAI QPTTIM^ Number (thousands) - ---------------- 184 VatlNtl-lAL t>tl IIINU Percentage of total population- ------------- 4 The most important geologic and physiographic feature _________Freshwater withdrawals, 1980_________ in Indiana is the boundary of Wisconsinan glaciation (fig. 1). Surface water and ground water, total (Mgal/d) - - - - - 1^000 North of this boundary, drift ranges in thickness from 50 to Ground water only (Mgal/d) -------------- 1,100 about 200 feet (ft). In the area covered only by pre-Wisconsi- Percentage of total- ------------------ 8 nan glaciations, the drift ranges in thickness from 0 to 50 ft. 'SSS^j^^-'^^^-" ------ 27 The bedrock, which is exposed in a small area of Indiana and T~ ~ j ,. .,.,,,. , ,. , Category of use underlies the glacial debris, generally dips gently from the =-^ structural high of the Cincinnati-Kankakee arch northeast ^SSS^SSoSSSb- --------------- 240 into the Michigan basin and southwest into the Illinois basin. Percentage of total ground water- ----------- 22 The bedrock ranges in age from Or dovician to Pennsylvanian Percentage of total public supply- ----------- 41 and is generally a carbonate clastic sequence typical of the Per capita (gal/d) ------------------ 152 ., . .... , . , , , Rural-supply withdrawals: midcontment. The most prolific water producers in the bed- Domestic: rock are Silurian and Devonian carbonate rocks. In the glacial Ground water (Mgal/d) - -------------- 12 mantle, the most prolific production is associated with glacial Percentage of total ground water - ----------- i , j i r-i , , ,. ,, , Percentage of total rural domestic ---------- 11 outwash and glaciofluvial channel deposits, although some Per capita (gal/d) ----------------- 63 isolated sand and gravel lenses within the till also can yield Livestock: large quantities of water Ground water (Mgal/d)- -------------- 8.0 Recharge to the ground-water system in Indiana is ESSS-SSSSSdT!': I I I I I I I I I I ' ,J derived mainly from precipitation. Annual precipitation industrial self-supplied withdrawals: ranges from 36 to 44 inches (in.) and averages 38 in. An Ground water (Mgal/d)- --------------- 600 annual average of 26 in. is returned to the atmosphere by ESg%S£tSS£Z&^ ------- 55 evapotranspiration, 8.5 to 9 in. is surface runoff to major Including withdrawals for thermoelectric power ----- 8 streams, and 3 to 3.5 in. recharges the ground-water system Excluding withdrawals for thermoelectric power - - - - 18 (C\arV IQRm Irrigation withdrawals: (^lark, iy«U). Ground water (Mgal/d)- --------------- 230 Percentage of total ground water- ----------- 21 PRINCIPAL AQUIFERS Percentage of total irrigation ------------- 98 The principal types of aquifers in Indiana are glacial outwash and glaciofluvial deposits and carbonate bedrock. Water is stored and transmitted through interconnected pores in the glacial outwash and glaciofluvial deposits and through GLACIAL AND GLACIOFLUVIAL AQUIFERS fractures and solution features in the carbonate bedrock. The ^. . ,. . . _. . .^. ..^ quality of ground water generally is good and is of the same Glaciof luvial Deposits and Glacial Outwash quality in the two principal types of aquifers. However, the Aquifers ground water is very hard [200 to 400 milligrams per liter The major aquifers in Indiana are of glacial origin. The (mg/L) as CaCO3] and, in places, contains as much as 3 mg/L most prolific of these are the glaciofluvial sands and gravels of iron and from 0.01 - 1.0 mg/L of manganese (Clark, 1980, associated with glacial channels and modern river systems and p. 80). Local ground-water quality problems exist (U.S. the outwash sands and gravels in the northeastern part of the Geological Survey, 1984, p. 123) but no widespread problems State (see fig. 1; table 2). The largest cities that rely primarily have been documented. The principal aquifers are described on ground water for public supplies are South Bend and below and in table 2, from youngest to oldest; their areal Elkhart (locations 3, 4, fig. 2); both obtain water from glacial distribution is shown in figure 1. outwash. In general, the glaciofluvial and glacial outwash 206 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Indiana [Gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Reports of the U.S. Geological Survey and the Indiana Department of Natural Resources] Aquifer name and description Well characteristics Depth (ft) Common May range exceed Yield (gal/min) Common May range exceed Remarks Glacial and glaciofluvial aquifers: Glaciofluvial aquifer: Sand gravel, some clay, and silt. Generally unconfined. Glacial outwash aquifers: Mostly sand and silt, some gravel, some clay. Generally unconfined. Wisconsinan till aquifer: isolated lenses of sand, gravel, and some silt. Generally surrounded in all three dimensions by silty clay and clay tills. Generally confined or at least semiconfined. Carbonate bedrock aquifers: Mississippian aquifers: Fractured limestones. Generally unconfined. Silurian-Devonian aquifers: Fractured limestone of very irregular distribution. Generally confined, especially where overlain by fine-grained glacial material. 20-60 80 100-500 1,500 Water calcium-magnesium bicarbonate type. Generally very hard, commonly exceeding 400 mg/L. hardness as calcium carbonate. 20-100 150 100-500 1,000 Areally extensive in northern Indiana. Water hard (exceeds 120 mg/L as calcium carbonate). 20-100 150 10-100 400 Aquifers of very local extent and not dependably present over entire area mapped in figure 1. Some isolated channels covered by till. As in other glacial and glaciofluvial aquifers in Indiana, water hard. 20-150 175 2-25 100 Limestones in middle of section are most productive rocks. Section has extensively developed karst. 50 - 250 300 10 - 100 600 Water quality generally hard. Sulfur may be problem. Well yields generally decrease toward southeastern part of State and brines occur in northwestern corner. aquifers are unconfined, but confining and semiconfining units, such as flowtills, commonly are located within these aquifers. The aquifers tend to be laterally discontinuous and limited in areal extent. Wisconsinan Till Aquifer Some isolated sand and gravel lenses within the Wisconsi- nan till are good aquifers, commonly producing 100 gallons per minute (gal/min). These aquifers are of very local extent. CARBONATE BEDROCK AQUIFERS Bedrock units in Indiana also serve as sources of water in some areas. Looking at these by geological period, certain generalities can be made. Mississippian Aquifers The Mississippian rocks contain a zone of limestone, in which an extensive karst terrane has developed. This lime- stone can produce significant quantities of water if wells intercept major solution-channel systems (Aten and others, 1982). Silurian-Devonian Aquifers The Silurian carbonate rocks and the overlying Devonian carbonate rocks commonly are used for small supplies but, in some areas, are capable of producing relatively large supplies of water. In Newton and Jasper Counties, these units provide water for irrigation. The water in these limestones generally is confined by overlying, fine-grained glacial material. OTHER AQUIFERS Pre-Wisconsinan till and loess deposits also are used locally but are not productive enough to support large with- drawals. Pennsylvanian coal-bearing rocks, Mississippian clastic rocks, and Devonian shales are poor aquifers, capable of sustaining only domestic household needs. Where local alternative ground- or surface-water supplies are not availa- ble, these rocks can yield as much as 10 gal/min of water of extremely variable quality. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS The distribution of major ground-water withdrawals and trends of ground-water levels are shown in figure 2. In general, water levels in observation wells have a seasonal variation of 3 to 5 ft, with the high levels in spring and the lows in the fall. In most parts of Indiana, water levels change little from year to year. The biggest single use of ground water in the State is for self-supplied industry, which comprises 55 percent of fresh ground-water withdrawal. Public- water supply and irrigation account for 22 and 21 percent, respectively, of the total ground-water withdrawal. In the South Bend area (St. Joseph County), 53 million gallons per day (Mgal/d) is withdrawn, of which 31 Mgal/d is for public supply. In Indianapolis (Ma- rion County), 52 Mgal/d is withdrawn, of which 40 Mgal/d is for industrial use. Most large withdrawals are either from National Water Summary Indiana 207 EXPLANATION Glaciofluvial aquifer Glacial outwash aquifer Wisconsin till - Isolated sand and gravel lenses I I Mississippian aquifers Silurian-Devonian aquifers Not a principal aquifer r CtfNTOfJ TIFTONJ/- ,j I ,J^- 0 '' ~^ BOONE '}| $- GlBSONf,____|; ._jfCeAWFOR ~i '^r>. J i-V, T ; / I _^. j__ . * i-, f\ 51 \WARRICKiJ j' " ___ Southern boundary of Wisconsin glaciation A A' Trace of cross section 100 MIUES l 1000' 500' Sea level Figure 1. Principal aquifers in Indiana. A, Geographic distribution. B, Physiographic diagram. C, Generalized cross section (A-A'). (See table 2 for a more detailed description of the aquifers. Sources: A, Compiled by K. J. Banaszak from U.S. Geological Survey files. B, Raisz, 1954. C, Compiled by K. J. Banaszak from U.S. Geological Survey files.) 208 National Water Summary Ground-Water Resources glacial outwash or glaciofluvial deposits. Heavy pumping has led to extensive cones of depression (a few square miles) locally, but, because of the very high permeability of these deposits and the amount of water available in storage, ground-water levels in most of these pumping centers have not been affected noticeably. (See hydrographs for locations 4 and 18, fig. 2.) When water levels do decline in response to pumping, as occurred in the central business district at In- dianapolis, recovery is swift when pumping ceases (Meyer and others, 1975). The trend of the annual greatest depth to ground water near location 16 (fig. 2) has been upward, probably due to a reduction in ground-water withdrawals. The graph of annual greatest depth to water near location 17 (fig. 2) shows a marked water-level decline and recovery for the period 1980-82. The decline in the yearly minimum water level probably resulted from a short period of intense pumping from nearby wells and does not indicate a long-term decline in aquifer storage. This conclusion is substantiated by the fact that yearly maximum water levels for the period 1980-82 increased 0.5 ft, and, for the period of record, yearly maximum water levels fluctuate only in a range of 2 ft. The most severe competition for water currently has developed for withdrawals that are less than those that appear in figure 2. These withdrawals, principally for irrigation, are made from the confined Silurian-Devonian aquifer along the border of Newton and Jasper Counties. Of 7 Mgal/d with- drawn in the two counties, 4 Mgal/d is withdrawn for irriga- tion. Water levels in U.S. Geological Survey observation wells in the area have dropped as much as 29 ft in two months because of stress from intensive seasonal withdrawals for irrigation. The recovery of these water levels occurs more slowly, but by January recovery is apparently complete. The history of irrigation and its study in this area has not been long enough nor is the data areally comprehensive enough to make deductions about the long-term effect of irrigation withdraw- als on the ground-water system. The issue, however, has been partially responsible for enactment of the Water-Resource Management Act discussed in the following section of the report. GROUND-WATER MANAGEMENT In 1983, Indiana enacted the Water-Resource Manage- ment Act, which established a Water Management Branch within the Division of Water in the Indiana Department of Natural Resources (Bruns, 1984). According to the Act, the most pressing and immediate need in Indiana is to establish registration for water-withdrawal facilities capable of remov- ing more than 100,000 gallons per day (gal/d). These facilities make withdrawals from ground or surface-water sources or both. Additionally, the Branch assesses the availability of water, maintains an inventory of the significant uses of water withdrawn, and plans for development, conservation, and use of the water for beneficial uses. The assessment, for which the inventory was begun, is to be accomplished by river basin. The Water-Resource Management Act considers Indiana's water resource as unitary; that is, no distinction is made in the Act between ground and surface water. The Act has been codified as 1C 13-2-6.1. Partial implementation of the Act occurred on January 1, 1984, and the Act was fully imple- mented on July 1, 1984. National Water Summary Indiana 209 EXPLANATION 4 Glacial outwash aquifer Unconfined O 5.0 25 O 25.1-50 O 50.1 - 55 Location number O B Withdrawal site I960 49 53 16 Glaciofluvial aquifer Unconfined I960 17 Glaciofluvial aquifer Unconfined 1985 #75 1980 1985 ~ 18 Glaciofluvial aquifer Unconfined 1975 1980 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 Geographic area Aquifer ... ... .do .............. ... ... .do .............. ... ... .do .............. ... ... .do .............. ... ... .do .............. ... ... .do .............. ... ... .do .............. ... ... .do .............. ... ... .do .............. ... ... .do .............. Principal uses . . . Do. . . . Do. . . . Do. . . . Do. . . . Do. . . . Do. . . . Do. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells In Indiana. (Sources: Withdrawal data from Clark, 1980; water-level data from U.S. Geological Survey files.) 210 National Water Summary Ground-Water Resources SELECTED REFERENCES Arihood, L. D., 1982, Ground-water resources of the White River Basin, Hamilton and Tipton Counties, Indiana: U.S. Geological Survey Water-Resources Investigations 82-48,69 p. Arihood, L. D., and Lapham, W. D., 1982, Ground-water resources of the White River Basin, Delaware County, Indiana: U.S. Geological Survey Water-Resources Investigations 82-47, 69 p. Aten, R. E., Melhorn, W. N., Bassett, J. L., Kieth, J. H., Powell, R. L., 1982, Hydrogeologic atlas of Indiana: Bloomington, Geo- science Research Associates, Inc., 31 plates. Bailey, Z. C., and Imbrigiotta, T. E., 1982, Ground-water resources of the glacial outwash along the White River, Johnson and Morgan Counties, Indiana: U.S. Geological Survey Water- Resources Investigations 82-4016, 87 p. Bechert, C. H., and Heckard, J. M., 1966, Ground water, in Lindsey, A. A., ed., Natural features of Indiana: Indianapolis, Indiana Academy of Science, 600 p. Bergeron, M. P. 1981, Effect of irrigation pumping on the ground- water system in Newton and Jasper Counties, Indiana: U.S. Geological Survey Water-Resources Investigations 81-83, 73 p. Bruns, T. M., 1984, A liquid asset: Outdoor Indiana, v. 49, no. 5, p. 26-28. Clark, G. D., ed., 1980, The Indiana water resource: Indianapolis, Indiana Department of Natural Resources, v. I, 508 p; v. II, 94 p. Greeman, T. K., 1983, Lineaments and fracture traces, Decatur County, Indiana: U.S. Geological Survey Open-File Report 82-918, 18 p. Harrell, M. A., 1935, Ground water in Indiana: Indiana University, unpublished Ph.D. thesis, 504 p. Imbrigiotta, T. E., and Martin, Angel, Jr., 1981, Hydrologic and chemical evaluation of the ground-water resources of northwest Elkhart County, Indiana: U.S. Geological Survey Water-Re- sources Investigations 81-53, 149 p. Indiana Department of Natural Resources, 1982, The 1980 survey of domestic self-supplied and livestock water uses in Indiana: Indianapolis, Indiana Department of Natural Resources, Divi- sion of Water, 17 p. Lapham, W. W., 1981, Ground-water resources of the White River Basin, Madison County, Indiana: U.S. Geological Survey Wa- ter-Resources Investigations 81-35, 112 p. Lapham, W. W., and Arihood, L. D., 1984, Ground-water resources of the White River Basin, Randolph County, Indiana: U.S. Geological Survey Water-Resources Investigations 83-4267, 86 p. Meyer, William, Reussow, J. P., and Gillies, D. C., 1975, Availability of Ground Water in Marion County, Indiana: U.S. Geological Survey Open-File Report 75-312, 87 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States, Washington, D.C., U.S. Geological Survey, 417 p. Shaver, R. H., and others, 1970, Compendium of rock-unit stratigra- phy in Indiana: Indiana Department of Natural Resources, Geological Survey Bulletin 43, 229 p. Shedlock, R. J., 1980, Saline water at the base of the glacial-outwash aquifer near Vincennes, Knox County, Indiana: U.S. Geological Survey Water-Resources Investigations 80-65, 54 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. U.S. Geological Survey, 1984, National water summary 1983 Hy- drologic events and issues: U.S. Geological Survey Water- Supply Paper 2250, 243 p. Prepared by Konrad J. Banaszak For further information contact District Chief, U.S. Geological Survey, 6023 Guion Road, Indianapolis, IN 46254 U.S. Geological Survey Water-Supply Paper 2275 IOWA Ground-Water Resources National Water Summary Iowa 211 Iowa has many aquifers that provide reliable sources of water for a variety of uses. In many areas of the State, ground water for rural domestic and livestock purposes can be ob- tained from shallow wells. Deeper and more productive aquifers, which are available under about 80 percent of the State, are used for large commercial, industrial, and public Table 1. Ground-water facts for Iowa [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Buchmiller and Karsten, 1983] Population served by ground water, 1980 water use in Iowa for 1980 was approximately 3.2 gallons per day (bgd). Of this total, about 2.1 bgd or From pubhc water-supply systems: 65 percent, was surface water used for thermoelectric power Number (thousands) ---------------- 1,641 generation (Buchmiller and Karsten, 1983). Of the remaining Percentage of total population - ------------ 56 1.1 bgd, 900 million gallons per day (Mgal/d) was ground- From rural self-supplied systems: water withdrawal, which comprised 81 percent of the total Pe^nTag^ot^populatio'n-' '-'-'-'- - - -' -' -' -' -' -' ?26 water use, excluding that used for the generation of thermoe- lectric power. Ground water provides water for 82 percent of __________Freshwater withdrawals. 1980_________ the population in Iowa, 100 percent of the water used for Surface water and ground water, total (Mgal/d) ------ 3,200 domestic purposes in rural areas (except in some rural water Ground water only (Mgal/d) --------------- 900 districts), 71 percent of the water used by self-supplied indus- Percentage of total - ----------------- 28 , - , . . . . . . Percentage ot total excluding withdrawals for tries, and 83 percent of the water used in irrigation projects thermoelectric power ---------------- 81 (Buchmiller and Karsten, 1983). Ground-water withdrawals r~~ : for various uses in 1980 and related statistics are given in ______________a egory o use_____________ table 1. Public-supply withdrawals: Ground water (Mgal/d)- --------------- 246 Percentage of total ground water- ----------- 27 Percentage of total public supply - ----------- 81 GENERAL SETTING Per capita (gal/d) ------------------ 150 . , , , , . Rural-supply withdrawals: The landscape of Iowa has been shaped by successive Domestic: Pleistocene glacial advances and retreats that have produced Ground water (Mgal/d)- -------------- 65 moderate relief and low elevations (fig. 1). Glaciation in Percentage of total ground water- ---------- 7 north-central Iowa has produced landforms that have been Percentage of total rural domestic ---------- 100 relatively unmodified by stream erosion. The Des Moines Livestock"3 (gal/d) ----------------- 85 Lobe is bordered by rolling hills of relatively low relief (lowan Ground water (Mgal/d) - -------------- 193 Surface) in the northeast and by the loess-mantled Northwest Percentage of total ground water ----------- 22 Iowa Plains (Prior, 1976). South of the lobe are the flat Percentage of total livestock - ------------ 100 divides and wide alluvial lowlands of the Southern Iowa Drift Industrial self-supplied withdrawals: Plain. The Western Loess Hills, which border the Missouri Ground water (Mgal/d)- - -------------- 320 . , . , Percentage of total ground water ------------ 36 River, are characterized by a narrow band of very unusual Percentage of total industrial self-supplied: topography that developed on loess more than 200 feet (ft) Including withdrawals for thermoelectric power - - - - 13 thick. The only area of extensive bedrock exposure is in the Excluding withdrawals for thermoelectric power - - - - 71 Paleozoic Plateau in extreme northeastern Iowa. This region Irrigation withdrawals: is relatively free of glacial drift and is characterized by deep Ground water (Mgal/d)- --------------- 76 11 u- u ui « j i * r * Percentage of total ground water - ----------- 8 valleys, high bluffs, and karst features. Percentage of total irrigation ------------- 83 A sequence of mostly sandstone, limestone, and dolomite ranging in age from Upper Cambrian through Cretaceous underlies the drift. The Paleozoic rocks have been folded to form a trough that dips gently toward the south and south- west. The Cretaceous rocks unconformably overlie the Paleo- PRINCIPAL AQUIFERS zoic rocks in the west and northwest. A network of stream The principal aquifers in Iowa are divided into two channels was incised into the bedrock before being buried by categories based on water-yielding and recharge characteris- Pleistocene glacial drift. tics. The first category consists of aquifers in bedrock very The principal aquifers in Iowa are recharged by infiltra- near the land surface and alluvial aquifers associated with tion of precipitation. Normal annual precipitation (1951-80) major streams. The second category consists of the very ranges from 26 inches (in.) in the northwest to 35 in. in the productive parts of deep, artesian aquifers that are distant southeast (P. J. Waite, State Climatologist, Des Moines, oral from their outcrop and subcrop recharge areas and are buried commun., 1984). Recharge to the water table is about 10 to 20 deeply beneath glacial drift and bedrock. Five principal percent of precipitation. Some direct recharge to bedrock aquifers are identified. They are described below and in table aquifers occurs in the Paleozoic Plateau of northeastern Iowa, 2; their areal distribution is shown in figure 1. (Surficial although local flow systems may discharge nearly equivalent aquifers are shown only on the cross section of figure 1 to amounts, leaving a small balance for regional recharge. provide more information on the plan view.) 212 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Iowa [Gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Steinhilber and Horick, 1970; Horick and Steinhilber, 1973, 1978; Burkart, 1982; Horick, 1984] Well characteristics Aquifer name and description Depth (ft) Yield (gal/min) Common May Common May range exceed____range exceed Remarks Surficial aquifers: Alluvial aquifers: Fine to coarse sand and gravel. Unconfined. 30-100 150 200-1,000 2,,000 Buried-channel aquifers: Coarse gravels. Confined. Glacial-drift aquifer: Pebbly and sandy drift, sand lenses, and poorly sorted sand and gravel. Unconfined. Dakota aquifer: Fine to very coarse grained and poorly cemented sandstone. Confined. Mississippian aquifer: Limestone and dolomites. Confined. Silurian-Devonian aquifer: Limestone and dolomite. Confined. Jordan aquifer: Dolomite and sandstone. Confined. Other aquifers: Dresbach aquifer: Sandstone. Confined. 50-100 200 10-100 500 15-400 600 5-10 20 100-600 600 100-250 1,000 100-300 500 50-100 900 100-800 1,000 150-400 4,000 300-2,000 3,000 100-1,000 1,000 400-1,000 2,000 50-1,000 2,000 Alluvium along streams near State bor- ders may yield from 1,000 to 2,000 gal/min, whereas interior stream valleys commonly yield only 200 to 300 gal/min with maximum about 2,000 gal/min. Very important source of water for public supply and industrial use. Water quality generally good; however, nitrate concentrations can exceed 10 mg/L (as nitrogen) in numerous locales. Bacteria and organic chemicals problems in selected areas. Only of local importance in central and eastern parts of State where most productive. Important for farms and rural homes, especially in western and southern Iowa. Greatest yields in glacial outwash in north-central Iowa. Water quality is generally good; however, nitrate concentrations can be greater than 10 mg/L (as nitrogen). Bacteria and organic chemicals problems in selected areas. Source of water for rural and public supply requirements in northwest and west-central Iowa. Yields of 1,500 gal/min have been obtained at Sioux City where aquifer recharged by overlying alluvium. Large concentrations of sulfate and dissolved solids present in numerous locals. Source of water for rural and public supply needs in north-central part of State. Smaller yields and poor quality water found in central and southeast Iowa. Water very mineralized. Important aquifer for meeting rural, public supply and industrial needs. In central and southern parts of State, water contains large concentrations solids. One of most dependable sources of water for large-capacity wells in State. Water contains in excess of 1,500 mg/L dissolved solids in southern and western parts of Iowa, but suitable for most uses in most of remainder of State. Aquifer only of local importance in a few counties in eastern Iowa. However, at these locales, a very important source of water for public supply and industrial use. National Water Summary Iowa 213 93 c 92 Sl/W#[ , \ Mk/r* v i ^^^\<> ts?^\\ -sX / ^ ^*4KM i^A^^lLp^ .*$/ > i i S«y- I i ^i R ? VkH«NeeCTtJ x«° Vl ^T-7T"7t-<r-M^~-k^M,4fWlXMt^^ A' EXPLANATION ____ I __ | Surficial aquifers [ [ Dakota aquifer | __ I Mississippian aquifer | __ I Silurian Devonian aquifer [ | Jordan aquifer Not a principal aquifer A A' Trace of cross section NORTHWEST IOWA PLAINS Figure 1. Principal aquifers in Iowa. A, Geographic distribution of most used aquifers. B, Physiographic diagram and divisions. C, Generalized cross section. (See table 2 for a more detailed detailed description of the aquifers. Sources: A, Hershey, 1969; Horick and Steinhilber, 1978. B, Raisz, 1954; Prior, 1976. C, Horick and Steinhilber, 1978.) 214 National Water Summary Ground-Water Resources SURFICIAL AQUIFERS The surficial aquifers are the alluvial aquifers that consist of fluvial and glaciofluvial deposits of Quaternary age beneath and adjacent to streams, the buried-channel aquifers that consist of glacial-outwash sand and gravel in bedrock chan- nels, and the glacial-drift aquifer, a term applied to thin and discontinuous sand and gravel lenses in the glacial drift. Aquifers of this type are present throughout Iowa; conse- quently, their distribution is not shown in figure 1. The alluvial flood plains and terraces of Iowa's major streams are important sources of water. These deposits are 100 to 160 ft thick along the Mississippi and Missouri Rivers and 30 to 70 ft thick along the principal interior streams. Yields from the Mississippi River alluvium range from 1,000 to 2,000 gallons per minute (gal/min). Those from the Mis- souri River alluvium range from 1,000 to 1,500 gal/min. Yields from the alluvium associated with major interior streams can be as much as 600 gal/min and, in some isolated instances, 2,000 gal/min has been obtained (Steinhilber and Horick, 1970). The buried-channel aquifers occupy bedrock valleys and underlie glacial drift in the State. Although relatively unex- plored, some of these valleys are known to be filled with outwash and alluvial sand-and-gravel deposits that yield from 10 to 100 gal/min. Where the buried channels are connected hydraulically to present-day streams, yields of 500 gal/min are obtainable. The buried-channel aquifers are most productive in the eastern and central parts of the State (Steinhilber and Horick, 1970). The glacial-drift aquifer consists of lenses of sand and gravel in a till matrix. The thickness of glacial drift in Iowa ranges from 0 to 600 ft and averages about 200 ft. Yields from some wells are less than 5 gal/min. Under favorable condi- tions, yields of 20 gal/min can be obtained (Steinhilber and Horick, 1970). The water quality in the alluvial and glacial-drift aquifers generally is suitable for most uses. However, concentrations of nitrate [greater than 10 milligrams per liter (mg/L)] exceed national drinking-water regulations (U.S. Environmental Pro- tection Agency, 1982a,b) in some wells. DAKOTA AQUIFER The Dakota aquifer consists of sandstone of Cretaceous age. It is the primary bedrock aquifer in northwestern Iowa and is of local importance in west-central Iowa. The sand- stone is fine to very coarse grained, is usually poorly cement- ed, and is from 10 to about 300 ft thick. Yields of more than 100 gal/min are common, but some wells can yield from 250 to 1,000 gal/min. The water is a calcium-magnesium sulfate type. In a relatively large area of northwestern Iowa, the water from the Dakota aquifer contains more than 1,500 mg/L of dissolved solids and 1,000 mg/L of sulfate. In some areas of northwestern Iowa, the Dakota aquifer contains naturally occurring concentrations of radium-226 and radi- um-228 in excess of 5 picocuries per liter (pCi/L). In these areas, the water may not be acceptable for domestic use, but has the potential for irrigation use, particularly on well- drained soils (Burkart, 1982). MISSISSIPPIAN AQUIFER The Mississippian aquifer consists mainly of limestone and dolomite and underlies about 60 percent of the State. Where it is overlain by glacial drift, the aquifer ranges in thickness from 100 to 300 ft; in the area where it is overlain by a thick sequence of Pennsylvanian and younger rocks, it has a maximum thickness of 600 ft. Yields range from 5 to 15 gal/min in domestic wells, from 25 to 50 gal/min in municipal wells in southeastern Iowa, and from 400 to 900 gal/min in municipal wells in north-central Iowa. In general, the water from the Mississippian aquifer contains more than 1,500 mg/L of dissolved solids. The dissolved-solids concentration of the water meets the recommended standard of 500 mg/L for drinking water (U.S. Environmental Protection Agency, 1982b) in a limited zone in the subcrop area. Water from Mississippian rocks may be of acceptable quality for most other uses in an additional zone of limited dimension south- west of the subcrop area (Steinhilber and Horick, 1970; Horick and Steinhilber, 1973). SILURIAN-DEVONIAN AQUIFER The Silurian-Devonian aquifer underlies about 90 percent of the State. Generally, this aquifer is 500 to 600 ft thick in the southwestern part of the State and 200 to 400 ft thick in the eastern and northern parts. The aquifer consists of dense limestone and dolomite and is very permeable as a result of extensive fracturing and enlargement of rock opening by solution. Most domestic wells yield at least 10 to 30 gal/min, whereas yields of 150 to 400 gal/min are common from public-supply wells. The aquifer is not used south and west of a line from Muscatine County northwest to Calhoun County and north to the Minnesota border. In the central and southern parts of the State, the water contains sulfate in excess of 500 mg/L, and dissolved-solids concentration exceeds 1,000 mg/L (Steinhilber and Horick, 1970; Horick, 1984). A sink- hole topography has developed where the aquifer material is exposed at or near land surface in northeast Iowa. The aquifer is particularly susceptible to surface contamination in this area. JORDAN AQUIFER The Jordan aquifer consists of the Jordan Sandstone of Late Cambrian age and dolomite and sandstone of the Prairie du Chien Group of Early Ordovician age. The aquifer gener- ally is 400 to 500 ft thick. It increases in thickness from 250 ft in northwestern Iowa to more than 800 ft in the southwestern part of the State. Extensive use is made of the aquifer by municipalities and industries in the eastern three-fourths of the State. Yields from wells range from 100 to 300 gal/min in the southwest to about 1,000 gal/min in the northeastern and central parts of the State. The water in the aquifer in north- western Iowa is a calcium-magnesium bicarbonate type. In north-central, central, and southeastern Iowa, the water con- tains about equal quantities of the major ions. In western Iowa, the water in the Jordan aquifer contains greater propor- tions of chloride and sulfate than in other areas. Some water supplies from the Jordan contain naturally occurring radium- 226 and radium-228 in excess of 5 pCi/L (Steinhilber and Horick, 1970; Horick and Steinhilber, 1978). Several com- munities in southern Iowa use the Jordan as an auxiliary supply of water. This aquifer, however, is not used in Mis- souri, just south of Iowa. DRESBACH AQUIFER The Dresbach aquifer, of Cambrian age, overlies rocks of Precambrian age and consists of a sequence of fine- to coarse-grained sandstone. This aquifer is only of local impor- tance in a few counties in northeast and east-central Iowa where it yields 2,000 to 3,000 gal/min. It is not used elsewhere in Iowa because of small yields (50 gal/min) and concentra- tions of dissolved solids exceeding 1,500 mg/L (Steinhilber and Horick, 1970). The area where this aquifer is used is too small to be included in figure 1. National Water Summary Iowa 215 SO 32 Alluvial aquifer Unconfined 1965 1975 80 & 5? g 90 _ i I 100 mt 110 120 33 Dakota aquifer Confined 1965 1975 20 30 40 34 Mississippian aquifer Unconfined 1955 1975 1985 g 80 so 3 100 ui 110 of IS 35 Silurian-Devonian aquifer Confined 1955 1985 8240 g250 3 §260 fc ffi 270 cc£ <t S 280 36 Jordan aquifer Confined 1955 1965 1985 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) Less than 5 0 5.0 - 25 Location number 2 Withdrawal site 4£ o^Hydrograph only WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Geographic Le Mars. ...... Metropolitan Sioux City. Cherokee. ..... Esterville. ..... Fort Dodge- Duncombe. Webster City .... Ames ........ Metropolitan Des Moines. Knoxville. ..... Oskaloosa ..... Grinnell ...... Tama-Toledo . . . Marsh all town . . . Waterloo-Cedar Falls. Waverly. ...... Charles City .... Mason City. .... Waukon- Postville. Oelwein ...... Independence . . . Cedar Rapids- Marion. Washington .... Mt. Pleasant .... Fort Madison . . . Muscatine ..... Davenport ..... Clinton ....... Maquoketa- Preston. Dubuque. ..... Aquifer Dakota .......... Dakota, alluvial ..... Dakota .......... Jordan .......... ... .do .......... ... .do .......... ... .do .......... Alluvial. ......... Alluvial, Jordan ..... Jordan .......... ... .do .......... Alluvial. ......... Jordan .......... ... .do .......... Alluvial. ......... Silurian-Devonian .... Jordan, Silurian- Devonian. Silurian-Devonian ... Jordan .......... ... .do .......... Jordan, Silurian- Devonian. Silurian-Devonian .... Alluvial, Jordan, Silurian-Devonian. Jordan .......... ... .do .......... Alluvial. ......... ... .do .......... Jordan .......... Dresbach ......... Dresbach, Jordan .... Dresbach, alluvial .... Principal uses Municipal. Do. Do. Industrial. Municipal. Municipal, industrial. Municipal. Do. Do. Do. Do. Do. Do. Municipal, industrial. Municipal. Do. Do. Do. Municipal, industrial. Do. Municipal. Do. Municipal, industrial. Municipal. Do. Do. Municipal, industrial. Industrial. Municipal, industrial. Do. Do. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Iowa. (Sources: Withdrawal data from Buchmiller and Karsten, 1983; Horick, 1984; water-level data from U.S. Geological Survey files.) 216 National Water Summary Ground-Water Resources GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS The distribution of principal ground-water withdrawals is shown in figure 2. The major areas of pumpage are in north-central, central, and east-central Iowa. In the alluvial aquifers that are hydraulically connected to streams, only small, long-term water-level declines have been recorded. To date, large withdrawals from the Mississippi River alluvium have not caused a general decline in water levels (Hansen and Steinhilber, 1977). An annual long-term regional water-level decline of about 0.3 ft in the Dakota aquifer in northwestern Iowa was noted by Burkart (1982). Periodically, larger wa- ter-level declines may occur in the Dakota aquifer, as shown by the hydrograph from location 33. Most wells in the Mississippian aquifer are located in areas where the aquifer underlies drift. Water levels away from pumping centers reflect changes in local recharge over time. Figure 2 includes a hydrograph from a water-table well in the Mississippian aquifer (location 34) and water-level changes in the Silurian- Devonian aquifer (location 35). Water-level changes due to pumping depend, in part, on aquifer permeability; for exam- ple, the water level in a well in Webster County that yields only 75,000 gallons per day (gal/d) from the Silurian-Devonian aquifer declined 61 ft in a little more than 30 years. In Linn County (location 23), however, water levels in industrial wells that pump large quantities of water from a more permeable part of the aquifer have declined only 27 to 30 ft since 1940 (Horick, 1984). Since the late 1800's, the potentiometric surface of the Jordan aquifer has declined from 50 to 100 ft regionally and from 175 to 200 ft at the major pumping centers (location 6, 19) (Horick and Steinhilber, 1978). The hydrograph (location 36) shown in figure 2 represents regional water-level declines for the Jordan aquifer. GROUND-WATER MANAGEMENT Laws regarding ground-water management in Iowa are found in the Code of Iowa, Chapter 455B; rules regarding ground-water management are in Chapter 900, Iowa Adminis- tration Code. These laws and rules are administered by the Iowa Department of Water, Air, and Waste Management. Under the authority of this agency, ground-water-withdrawal permits are granted, restrictions on withdrawals are enforced, and ground-water injection is regulated. The Iowa Geological Survey is the State's manager of water-resource information and supports various activities that assess the ground-water conditions in the State. The University of Iowa Hygienic Laboratory system is responsible for analysis of the quality of community supplies. SELECTED REFERENCES Buchmiller, R. C., and Karsten, R. A., 1983, Estimated water use in Iowa, 1980: Iowa Geological Survey Miscellaneous Map Series 9. Burkart, M. R., 1982, Availability and quality of water from the Dakota aquifer, northwest Iowa: U.S. Geological Survey Open-File Report 82-264, 83 p. Hansen, R. E., and Steinhilber, W. L., 1977, Geohydrology of Muscatine Island, Muscatine County, Iowa: Iowa Geological Survey Water-Supply Bulletin No. 11, 60 p. Hershey, H. G., 1969, Geologic map of Iowa: Iowa Geological Survey. Horick, P. J., 1984, Silurian-Dovonian aquifer of Iowa: Iowa Geological Survey Miscellaneous Map Series 10. Horick, P. J., and Steinhilber, W. L., 1973, Mississippian aquifer of Iowa: Iowa Geological Survey Miscellaneous Map Series 3. __1978, Jordan aquifer of Iowa: Iowa Geological Survey Miscel- laneous Map Series 6. Prior, J. C., 1976. A regional guide to Iowa landforms: Iowa Geological Survey, Educational Series 3, 72 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Steinhilber, W. L., and Horick, P. J., 1970, Ground-water resources of Iowa, in P. J. Horick, ed., Water resources of Iowa, Iowa City, University Printing Service, p. 29-49. U.S. Environmental Protection Agency, 1982a, Maximum contami- nant levels (subpart B of part 141, National interim primary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100-149, revised as of July 1, 1982, p. 315-318. __1982b, Secondary maximum contaminant levels (section 143.3 of part 143, National secondary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100-149, revised as of July 1, 1982, p. 374. Prepared by Richard A. Karsten and Michael R. Burkart For further information contact District Chief, U.S. Geological Survey, P.O. Box 1230, Iowa City, IA 52244 U.S. Geological Survey Water-Supply Paper 2275 National Water Summary Kansas 217 KANSAS Ground-Water Resources Table 1. Ground-water facts for Kansas [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day] Population served by ground water, 19801 Kansans rely on ground-water resources for public, rural, industrial, and irrigation water supplies. In the western two- thirds of the State, abundant ground-water resources provide most of the water supplies. Ground-water resources are limit- ed in the eastern one-third of the State and surface-water resources provide most of the water supplies in that area. XT , ,, , x , , _, ^ , ,. , ,. ,,T-ii- , Number (thousands) - ----------------- 1,153 ,u ,Pr°Uo WatCr SUPPllCS ab°Ut 5 '6 bllh°n 8all°nS PCr day Percentageoftotalpopulation -------------- 49 (bgd), or 85 percent of the water used in Kansas. Public and From public water-supply systems: rural systems provide ground water to almost 1.2 million Number (thousands) ----------------- 903 people (about 49 percent of the State's population). Approxi- Percentageoftotalpopulation- ------------ 38 mately 93 percent of the ground water withdrawn (5.2 bgd) is From rural self-supplied systems: used for irrigation. Ground-water withdrawals during 1980 pSSS^gf^L^ton-" '-'-'-'-'-'- '- '-'-'-'- '- 1? for selected uses and related statistics are given in table 1. ______ Freshwater withdrawals. 19802________ Additional water-use data are available from the Kansas - Water Office. Surface water and ground water, total (Mgal/d) ------ 6,600 Ground water only (Mgal/d) -------------- 5,600 GENERAL SETTING Percentage of total- - - - ------------- 85 Percentage of total excluding withdrawals for Ground-water conditions differ with physiography and thermoelectric power - - - - - - - - - - - - - - 89 geology. Physiographic provinces in Kansas (fig. 1) are the Category of use Osage Plains and Dissected Till Plains sections of the Central Lowlands province, the Ozark Plateaus province, and the Public-supply withdrawals: Grea, Plains province (Fenneman, .946). pSe^eStoXcund wa,^ I I - - - I - I ~- - - '1 The Osage and Dissected Till Plains and the Ozark Percentage of total public supply - ----------- 48 Plateaus annually receive from 30 to 45 inches (in.) of precipi- Per capita (gal/d) ------------------ 155 tation. Although rain provides an abundant source of re- Rural-supply withdrawals: charge, geology determines the availability of ground water. Domestic: Pennsylvanian and Permian rocks (shale, limestone, and PeTelge^ground"water -" I I I I I I I I I I 04 sandstone) crop out in the Osage Plains and dip toward the Percentage of total rural domestic ---------- 86 northwest. Glacial drift (clay, silt, sand, gravel, and boulders) Per capita (gal/d) ----------------- 100 of Pleistocene age mantles large areas of Pennsylvanian and Livestock: Permian rocks in the Dissected Till Plains. Weathered and Ground water (Mgal/d)- -------------- 35 sandy dolomite of Cambrian and Ordovician age underlie ,he pSSSrfSSKSSdT-f I I I I I I I I I I I « Ozark Plateaus at depths of 300 feet (ft) or more and dip industrial self-supplied withdrawals: towards the northwest. Ground water (Mgal/d)- --------------- 190 The Great Plains receives from 15 to 30 in. of rainfall Percentage of total ground water- ----------- 3 annually, and recharge is limited in the western part. Creta- Percentage of total industrial self-supplied: ceous rocks (shale, sandstone, limestone, and chalk) crop out Including withdrawals for thermoelectric power - - - - 35 . ., >.i ^ ^.1-^.1 j j- j , Excluding withdrawals for thermoelectric power - - - - 77 in the northeast one-quarter of the area and dip toward the irrigation withdrawals: northwest. Cenozoic deposits (clay, silt, sand, and gravel) as Ground water (Mgal/d)- -------------- 5,200 much as 500 ft thick overlie Cretaceous rocks in the remainder Percentage of total ground water ------------ 93 of the area. Alluvial deposits (clay, silt, sand, and gravel) of Percentage of total irrigation ------------- 92 Quaternary age are present in major river valleys throughout , the State Total population from Murray (1982); population served by public water-supply systems from Solley, Chase, and Mann (1983); population served PRIMPIPAI AOI IIFPRQ by rural water-supply systems from U.S. Bureau of the Census (1983). ri-UINOirML MUUirCrlCJ Data from Solley chase, and Mann (1983). Rural domestic supplies Principal aquifers in Kansas consist of two types uncon- estimated from data in U.S. Bureau of the Census (1983). solidated gravel, sand, silt, and clay, and consolidated sand- stone, limestone, and dolomite. The principal aquifers are milligrams per liter (mg/L), and concentrations of manganese described below and in table 2, from youngest to oldest; their can exceed 0.05 mg/L. areal distribution is shown in figure 1. In the Great Plains, wells developed in unconfined allu- vial aquifers of the Arkansas, Republican, and Pawnee River ALLUVIAL AQUIFERS valleys generally yield more than 500 gal/min. The water The Kansas River alluvial aquifer is an important source generally is a calcium bicarbonate type that is suitable for of water along the common border of the Osage and Dissected most uses. Locally, concentrations of dissolved solids greater Till Plains. The aquifer consists of unconsolidated fluvial than 500 mg/L, chloride greater than 250 mg/L, and nitrate deposits of Quaternary age and is unconfined. Wells typically greater than 10 mg/L can result from discharge of saline water yield more than 500 gallons per minute (gal/min). The water from underlying bedrock, contamination from oilfields, and generally is a calcium bicarbonate type that is suitable for agricultural practices. Naturally occurring concentrations of most uses. Concentrations of iron commonly exceed 0.3 selenium greater than 0.01 mg/L and gross-alpha radioactivity 218 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Kansas [Gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Reports of the U.S. Geological Survey and Kansas agencies] Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Alluvial aquifers: Quaternary fluvial deposits of clay, silt, sand, and gravel. Generally unconfined. Glacial-drift aquifer: Pleistocene glacial deposits of clay, silt, sand, and gravel. Generally unconfined. High Plains aquifer: Fluvial and eolian deposits of clay, silt, sand, and gravel of Cenozoic age. Generally unconfined. Great Plains aquifer: Dakota and Cheyenne Sandstones of Cretaceous age. Generally unconfined. Chase and Council Grove aquifer: Limestones of Chase and Council Grove Groups of Permian age. Generally unconfined. Douglas aquifer: Channel sandstone of Pennsylvanian age. Generally unconfined. Ozark aquifer: Weathered and sandy dolomites of Arbuckle Group. Cambrian and Ordovician age. Confined. 10-150 10-500 1,000 Well yields in Kansas, Arkansas, Republican, and Pawnee River valleys exceed 500 gal/min. Wells in other valleys usually yield less than 100 gal/min. Locally, water from alluvial aquifers can have large concentrations of dissolved solids, chloride, sulfate, nitrate, iron, and manganese. Large concentrations of sele- nium and naturally occurring gross-alpha radioactivity sometimes occur in water from northern part of Great Plains. 10-300 10-100 500 Water from shallow wells generally a calcium bicarbonate type with less than 500 mg/L dissolved solids, but large concentrations of nitrate can occur. Water from deep wells can have large concentrations of dissolved solids, chloride, sulfate, iron, or manganese. 10-450 500-1,000 1,500 Water generally a calcium bicarbonate type with concentrations of dissolved solids less than 500 mg/L, but large concentrations of fluoride and selenium can occur in northern Great Plains. Provides water supplies for Dodge City, Garden City, Great Bend, Pratt, Hutchinson, McPherson, Wichita, and most other towns in Great Plains. 20-200 10-100 1,000 Water quality variable. Calcium bicarbonate type water with less than 500 mg/L of dissolved solids produced where the aquifer is exposed. Sodium bicarbonate or sodium chloride type water with large concentrations of dissolved solids is produced west and north of the surface exposure. Large concentrations of iron occur in water from some wells. Some wells in Finney, Ford, and Hodgeman Counties can yield more than 1,000 gal/min. 20-200 10-20 200 Water generally a calcium bicarbonate type with concentrations of dissolved solids less than 500 mg/L. Water from some wells can have large concentrations of sulfate. Wells in Butler and Cowley Counties can produce water with large concentrations of dissolved solids. Concentrations of dissolved solids and chloride large west of the surface exposure, and water is not used. 5-400 10-40 100 Water ranges from a calcium bicarbonate type, with less than 500 mg/L of dissolved solids where aquifer is exposed, to a sodium bicarbonate or sodium chloride type, with large concentrations of dissolved solids at depth or west of surface exposure. Concentrations of fluoride may be large. Equivalent to Vamoosa-Ada aquifer in Oklahoma. 500 - 1,800 30 - 150 500 Water generally a calcium bicarbonate type with less than 500 mg/L of dissolved solids in the Ozark Plateaus and in extreme southeast corner of the Osage Plains. Sodium bicarbon- ate chloride or sodium chloride type water with large concentrations of dissolved solids is produced in rest of Osage Plains. Hydrogen sulfide gas, or large concentrations of gross- alpha radioactivity or iron, can occur in water from some wells. Equivalent to Roubidoux aquifer in Oklahoma. National Water Summary Kansas 219 50 100 MILES GREAT PLAINS PROVINCE DISSECTED TILL PLAINS ' SECTION OF CENTRAL LOWLANDS PROVINCE OSAGE PLAINS SECTION OF CENTRAL LOWLANDS PROVINCE ARK PLATEAUS PROVINCE EXPLANATION k^J Alluvial aquifers __I Glacial drift aquifers High Plains aquifer Great Plains aquifer I I Chase and Council Grove aquifers I I Douglas aquifer III Ozark aquifer Not a principal aquifer Figure 1. Principal aquifers in Kansas. A, Geographic distribution. B, Physiographic diagram and divisions. (See table 2 for more detailed descriptions of the aquifers. Sources: A, Bayne, 1975; Luckey and others, 1981. B, Fenneman, 1946; Raisz, 1954.) 220 National Water Summary Ground-Water Resources greater than 15 picocuries per liter (pCi/L) commonly are present in water from alluvial aquifers in the northern Great Plains. GLACIAL-DRIFT AQUIFER The glacial-drift aquifer is a major source of water in the Dissected Till Plains. The aquifer consists of unconsolidated glacial deposits of Pleistocene age and generally is unconfined. Wells yield from 10 to about 500 gal/min. Shallow wells generally produce a calcium bicarbonate water that is suitable for most uses, but nitrate concentrations can exceed 10 mg/L. Deep wells can produce very mineralized water with concen- trations of dissolved solids greater than 500 mg/L, sulfate and chloride greater than 250 mg/L, and iron exceeding 0.3 mg/L. HIGH PLAINS AQUIFER The High Plains aquifer is the most important and extensively used aquifer in Kansas. The aquifer consists of thick unconsolidated fluvial and eolian deposits of Cenozoic age and generally is unconfined. The aquifer is present in nearly three-fourths of the Great Plains. Wells yield from 500 to about 1,500 gal/min. The water generally is a calcium bicarbonate type that is suitable for most uses. Concentra- tions of fluoride greater than 1.4 mg/L and selenium greater than 0.01 mg/L are present in some water from northern parts of the High Plains aquifer. GREAT PLAINS AQUIFER The Great Plains aquifer is a major source of water in the northeastern quarter of the Great Plains, where the aquifer material is exposed at the land surface, and in the southern part of the Great Plains, where it is exposed or is directly overlain by Cenozoic deposits. The aquifer consists of the Dakota and Cheyenne Sandstones of Cretaceous age and generally is unconfined. Wells yield from 10 to 100 gal/min in the northeast to more than 1,000 gal/min in the south. The water generally is a calcium bicarbonate type in areas where the aquifer is unconfined. However, sodium and chloride concentrations increase with depth, and the water is not used northwest of the area shown in figure 1. Some wells yield water with concentrations of iron exceeding 0.3 mg/L. CHASE AND COUNCIL GROVE AQUIFER The Chase and Council Grove aquifer is a major source of water where it is exposed in the Osage Plains. The aquifer consists of limestones of the Chase and Council Grove Groups of Permian age. Well yields range from 10 to about 200 gal/min. The water generally is a calcium bicarbonate type that is suitable for most uses, although concentrations of sulfate exceed 250 mg/L locally. The water is very mineralized (dissolved-solids and chloride concentrations exceed 500 mg/L and 250 mg/L, respectively) west of the area shown in figure 1 and is not used. DOUGLAS AQUIFER The Douglas aquifer is a source of water where it is exposed in the Osage and Dissected Till Plains. The aquifer consists of channel sandstone of the Douglas Group of Penn- sylvanian age. In these areas, the aquifer generally is uncon- fined, and wells yield from 10 to about 100 gal/min. The water generally is a calcium bicarbonate type that is suitable for most uses. Some wells produce water with fluoride concentra- tions that exceed 1.4 mg/L. As in the case of the Chase and Council Grove aquifer, west of the area shown in figure 1, the water is not used because of its high mineral content. OZARK AQUIFER The Ozark aquifer is the major source of ground water in the Ozark Plateaus. The aquifer consists of weathered and sandy dolomites of the Arbuckle Group of Cambrian and Ordovician age and is confined. The aquifer does not crop out in Kansas; at the shallowest point, it is 300 ft below land surface. Wells yield from 30 to about 500 gal/min. The water generally is a calcium bicarbonate type that is suitable for most uses. Water in some wells contains excessive concentra- tions of iron (greater than 0.3 mg/L) and naturally occurring gross-alpha radioactivity (greater than 15 pCi/L) (Spruill, 1983). In the Osage Plains, water from the Ozark aquifer becomes very mineralized with depth and toward the north- west, and hydrogen sulfide gas may be present. The water is not used west of the area shown in figure 1. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Although ground water is withdrawn throughout the State, seven major pumping centers produce most of the water. At locations 1 to 5 (fig. 2), water is withdrawn from the High Plains aquifer. These five pumping centers are Ground- water Management Districts (GMD's), which are political subdivisions of the State government locally organized to manage ground-water resources. Location 6 is the Kansas River valley in northeast Kansas. At location 7, water is withdrawn from the Ozark aquifer in southeast Kansas. Ground-water withdrawals are estimated from water rights granted by the Kansas State Board of Agriculture, Division of Water Resources. Estimates for pumping centers at locations 1 to 5 were provided by the GMD's. Estimates for pumping centers at locations 6 and 7 were obtained from unpublished data of the Kansas Division of Water Resources. Approximately 710 million gallons per day (Mgal/d) of water is withdrawn from the High Plains aquifer at location 1 (fig. 2) which includes parts of Wallace, Greeley, Wichita, Scott, and Lane Counties. Because recharge is insufficient to replenish ground water withdrawn for irrigation, water levels had declined from 10 to 100 ft by 1980 (Luckey and others, 1981). The hydrograph shows that the greatest rate of water level decline occurred from about 1962 through 1975. At location 2 (fig. 2), which includes parts of McPherson, Harvey, Reno, and Sedgwick Counties, approximately 190 Mgal/d of water is withdrawn from the High Plains aquifer. Although ground water is used extensively for irrigation and public supplies, recharge from precipitation generally had prevented water levels from declining more than 10 ft by 1980 (Luckey and others, 1981). The largest decline, about 30 ft, has occurred in the well field of the city of Wichita. The hydrograph from the Wichita well field (location 2, fig. 2) shows that the water level declined rather sharply from 1939 until 1957. The relative stability of water levels since about 1960 is primarily the result of decreased pumpage due to the increased use of surface water for public supplies. Approximately 3.3 bgd of water is withdrawn from the High Plains aquifer at location 3 (fig. 2) which includes Stanton, Morton, Grant, Stevens, Haskell, Seward, Gray, Ford, and parts of Hamilton, Kearny, Finney, Hodgeman, and Meade Counties. Because precipitation is insufficient to replenish ground water withdrawn for irrigation, water levels had declined more than 150 ft in parts of the area by 1980 (Luckey and others, 1981). The hydrograph (location 3, fig. 2) shows that the greatest rate of decline occurred from about 1955 through 1970. Approximately 920 Mgal/d of water is withdrawn from the High Plains aquifer at location 4 (fig. 2), which includes National Water Summary Kansas 221 EXPLANATION Ground-water withdrawals, 1983 (million gallons per day) O 10-150 O 151 - 700 Q 701 - 3000 O 3001 - 4000 Location number 2 O Withdrawal site so 60 70 80 90 100 110 120 130 MO 1 High Plains aquifer Unconfined 1935 1945 1955 1965 1975 1985 1935 80 SO 100 no 120 130 140 150 160 170 3 High Plains aquifer Unconfined 1945 1955 1965 1945 1975 1985 100 104 108 112 116 120 124 128 132 136 4 High Plains aquifer Unconfined I I I I I I I I I 1935 1945 1955 1975 u 10 ao 30 40 SO 60 70 80 90 19 5 High PlainsX ^^_^ /\. aquifer ^^ ^^-\^^/ ^\^_ Unconfined - - - - I I I I | I I I I u to 20 3D 40 50 60 70 80 90 6 Kansas River Unconfined alluvial aquifer * > ^ _^ - * :---- i i i i i i i i i 55 1945 1955 1965 1975 1985 1935 1945 1955 1965 1975 I9S ^^MJ 270 290 310 330 350 370 390 410 430 \ 7 Ozark aquifer Confined _ \r^-Missing record \ 1 **" \ 1 \l x\ _ 1 ^1 I I I I I I / ' 1 1 1 1935 1945 1955 1965 1975 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 Geographic area Western Kansas, Ground- water Management District 1. Equus Beds, Groundwater Management District 2. Southwest Kansas, Ground- water Management District 3. Northwest Kansas, Ground- watar Management District 4. Big Bend, Groundwater Management District 5. Kansas River valley. northeast Kansas. Southeast Kansas ..... Aquifer High Plains. . . . ... .do ...... ... .do ...... ... .do ...... ... .do ...... Kansas River alluvial. Ozark. ...... Principal uses Irrigation, public supply. Do. Do. Do. Do. Irrigation, industrial. Public supply. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Kansas. (Sources: Withdrawal data from Groundwater Management Districts 1-5 and Kansas State Board of Agriculture, Division of Water Resources; water-level data from U.S. Geological Survey.) 222 National Water Summary Ground-Water Resources Sherman, Thomas, Sheridan, and parts of Cheyenne, Raw- lins, Decatur, Graham, Wallace, Logan, and Gove Counties. Although ground water is withdrawn for irrigation in this area and precipitation provides little recharge, irrigation began later and is not developed as extensively as in other High Plains pumping centers. Ground-water levels in this area had declined generally less than 50 ft by 1980 (Luckey and others, 1981). The hydrograph (location 4, fig. 2) shows that the greatest rate of water-level decline occurred from about 1970 through 1983. Approximately 910 Mgal/d of water is withdrawn from the High Plains aquifer at location 5 (fig. 2), which includes Stafford, Pratt, and parts of Kiowa, Edwards, Pawnee, Barton, Rice, and Reno Counties. Ground water is used extensively for irrigation, but increased recharge and de- creased pumping during wet years can raise water levels significantly, as indicated by the well hydrograph (location 5, fig. 2). Ground-water levels in this area had declined generally less than 10 ft by 1980 (Luckey and others, 1981). However, declines of 25 ft have been observed locally. Approximately 230 Mgal/d of water is withdrawn from the Kansas River alluvial aquifer at location 6 (fig. 2), which includes the Kansas River valley in Geary, Riley, Wabaunsee, Pottawatomie, Shawnee, Douglas, Jefferson, Johnson, Leav- enworth, and Wyandotte Counties. Although ground water is used for irrigation and industrial supplies, increased recharge from precipitation and streamflow has kept water levels from declining significantly (location 6, fig. 2). Approximately 14 Mgal/d of water is withdrawn from the Ozark aquifer in location 7 (fig. 2), which includes parts of Cherokee, Crawford, and Bourbon Counties. Although the quantity of ground water withdrawn from this area is consid- erably less than that from other areas, recharge has not increased because of confined conditions, and water levels have declined locally as much as 200 ft, based on predevelop- ment and 1980 potentiometric-surface maps (MacFarlane and others, 1981). GROUND-WATER MANAGEMENT Kansas has five State agencies and one type of local State government unit with major responsibilities for managing ground water. The Kansas Water Office is the water planning, policy, and coordination agency for the State (Kansas Statutes Annotated (K.S.A.) 74-2605 et seq.). It prepares State plans for water-resource management, conservation, and develop- ment. The Kansas Water Authority, a part of the Kansas Water Office (K.S.A. 74-2605 et seq.), is responsible for advising the Governor, Legislature, and Director of the Kan- sas Water Office on water-policy issues. The Kansas State Board of Agriculture, Division of Water Resources, administers laws (K.S.A. 82a-701 et seq.) related to the conservation and use of water resources, includ- ing appropriation of ground water and assisting with the organization of Groundwater Management Districts. The Kansas Department of Health and Environment, Division of Environment, has regulatory authority over mat- ters dealing with water pollution (K.S.A. 65-161 et seq., K.S.A. 55-1003 et seq., K.S.A. 82a-1035 through 1038, and K.S.A. 82a-1201 et seq.). This agency is responsible for collecting, analyzing, and interpreting ground-water-quality data; developing water-quality-management plans; and re- sponding to emergency water-pollution problems. The Kansas Corporation Commission has a mandate (K.S.A. 55-115 et seq.) to protect fresh ground-water supplies from adverse effects of mineral-development activities. The Kansas Geological Survey conducts ground-water research, including the collection, analysis, and interpretation of ground-water-quantity and quality data (K.S.A. 76-322, 76-2610, 82a-903,55-128). Groundwater Management Districts (GMD), locally managed political subdivisions of the State, have been formed as a result of the Groundwater Management District Act of 1972 (K.S.A. 82a-1020, et seq.). There are currently five GMD's in Kansas: District 1, western Kansas; District 2, Equus beds; District 3, southwest Kansas; District 4, north- west Kansas; and District 5, Big Bend. Each District is charged with managing ground-water resources within its boundaries. SELECTED REFERENCES Bayne, C. K., 1975, General availability of ground water and normal annual precipitation in Kansas: Kansas Geological Survey Map M-4A. Fenneman, N. M., 1946, Physical divisions of the United States: U.S. Geological Survey special map. Heath, R. C., 1984, Ground-water regions of the United States: U.S. Geological Survey Water-Supply Paper 2242, 78 p. Kansas Department of Health and Environment, 1982, Ground-water quality management plan for the State of Kansas: Kansas Department of Health and Environment Bulletin No. 3-4, 77 p. Kansas Water Office, 1984, Kansas water supply and demand esti- mates: Kansas Water Office, State Water Plan, Background Paper No. 15, 119 p. Keene, K. M., and Bayne, C. K., 1977, Ground water from Lower Cretaceous rocks in Kansas: Kansas Geological Survey Chemi- cal Quality Series 5, 18 p. Luckey, R. R., Gutentag, E. D., and Weeks, J. B., 1981, Water-level and saturated-thickness changes, predevelopment to 1980, in the High Plains aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: U.S. Geological Survey Hydrologic Investigations Atlas HA- 652. MacFarlane, P. A., Whittemore, D. O., and Hathaway, L. R., 1981, The hydrogeology and chemical quality in the lower Paleozoic aquifers in southeast Kansas and adjoining areas of Missouri and Oklahoma: Kansas Geological Survey Open-File Report 81-16, 48 p. Merriam, D. F., 1963, The geologic history of Kansas: Kansas Geological Survey Bulletin 162, 317 p. Murray, W. A., 1982, Kansas statistical abstract 1982-83: Lawrence, University of Kansas Center for Public Affairs, 280 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Spruill, T. B., 1983, Statistical summaries of selected chemical con- stituents in Kansas ground-water supplies, 1976-81: U.S. Geo- logical Survey Open-File Report 83-263, 29 p. Taylor, O. J., 1978, Summary appraisals of the Nations's ground- water resources Missouri Basin region: U.S. Geological Survey Professional Paper 813-Q, 41 p. U.S. Bureau of the Census, 1983, 1980 Census of housing: U.S. Department of Commerce, v. 1, chapter B, part 18. U.S. Geological Survey, 1970, The national atlas of the United States: Washington, D.C., 417 p. Weeks, J. B., and Gutentag, E. p., 1981, Bedrock geology, altitude of base, and 1980 saturated thickness of the High Plains aquifer in parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming: U.S. Geological Survey Hydrologic Investigations Atlas HA-648. Prepared by Hugh E. Bevans, Timothy B. Spruill, and Joan F. Kenny For further information contact District Chief, U.S. Geological Survey, 1950 Constant Avenue, Campus West, Lawrence, KS 66046 U.S. Geological Survey Water-Supply Paper 2275 National Water Summary Kentucky 223 KENTUCKY Ground-Water Resources Table 1. Ground-water facts for Kentucky [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Mull and Lee, 1984] Population served by ground water, 1980 Ground water is an important resource in Kentucky. Excluding water used for power generation, about 22 percent of the water use in the State is from ground-water sources. About 31 percent of the population is served by ground water. In large karst areas in the central part of the State where streams are sparse, ground water is the only source of supply. In rugged areas in the coal fields, residents depend on ground Number (thousands) - ----------------- 1,145 water because surface flows generally are not reliable. Percentage of total population -------------- 31 ,_ , ...... , From public water-supply systems: Ground-water withdrawals for various uses in 1980 and relat- Number (thousands) ----------------- 363 ed statistics are given in table 1. Percentage of total population- ------------ 10 Kentucky is located in three physiographic provinces From rural self-supplied systems: .. ^ . , ', T * - T * A A i u- Number (thousands) ----------------- 782 the Coastal Plain, Interior Low Plateaus, and Appalachian Percentage of total population- ------------ 21 Plateaus. The Coastal Plain province and the major river Fresh water withdrawals, 1980 valleys are underlain by unconsolidated deposits. The rest of - ., c . t . , , . , ,., . , ,. . Surface water and ground water, total (Mgal/d) ------ 4,600 the State is underlain by consolidated sedimentary rocks. Ground water only (Mgal/d) --------------- 180 Recharge to the ground-water system in Kentucky is Percentage of total- ------------------ 4 derived mostly from precipitation. Average annual pre- Percentage of total excluding withdrawals for cipitation (1948-77) ranges from about 40 inches (in.) in the thermoelectric power ---------------- 22 northern part of the State to about 52 in. in the south-central _____________Category of use_____________ and southeastern parts. Recharge rates differ according to Public-supply withdrawals: geology and land forms but average about 9 percent of the Ground water (Mgal/d)- --------------- 48 0 ... 6 ^ Percentage of total ground water- ----------- 26 precipitation. Percentage of total public supply- ----------- 13 Per capita (gal/d) ------------------ 132 Rural-supply withdrawals: PRINCIPAL AQUIFERS T±d water (Mga./d,- ...--...-...-. 39 Aquifers consist mostly of unconsolidated sand, gravel, Percentage of total ground water- ---------- 21 silt, and clay in the Coastal Plain province and in the alluvial Percentage of total rural domestic ---------- 91 .,,'.. j r j *u A i u- Per capita (gal/d) ----------------- 50 aquifer along the rivers and of sandstone in the Appalachian Livestock- Plateaus province. Aquifers consist mostly of sandstone in Ground water (Mgal/d)- --------------- 2 the coal field of the Interior Low Plateaus province and Percentage of total ground water - ----------- i , f ,- , . , _ , . Percentage of total livestock- ------------- 5 mostly of limestone in the remainder of that province in industrial self-supplied withdrawals: Kentucky. The aquifers are described below and in table 2; Ground water (Mgal/d)- --------------- 93 their areal distribution is shown in figure 1. Percentage of total ground water- ----------- 51 Percentage of total industrial self-supplied: Including withdrawals for thermoelectric power ----- 2 Excluding withdrawals for thermoelectric power - - - - 25 ALLUVIAL AQUIFER Irrigation withdrawals: . . . , ^ . Ground water (Mgal/d)- --------------- 0.3 The alluvial aquifer along the Ohio River is by far the Percentage of total ground water- ----------- .2 most intensively used aquifer in Kentucky. Many towns and Percentage of total irrigation -------------- 6 industries located along the river depend upon large surface supplies from the river and on ground-water supplies from shallow wells in the alluvium. Properly constructed wells near the river can induce infiltration of streamflow, which ensures TERTIARY AND CRETACEOUS AQUIFERS dependable supplies (Gallaher and Price, 1965, p. 2). The The Tertiary and Cretaceous aquifers are dependable quality of water in the alluvium generally is suitable for most sources of potable ground water and could provide more uses but may need to be treated for excessive hardness and water than is used at present (Hosman and others, 1968, p. iron for some uses. Hardness commonly exceeds 300 milli- Dll; Boswell and others, 1965, p. C9). These aquifers crop grams per liter (mg/L) as calcium carbonate, and iron concen- out in the Coastal Plain province and thicken and dip to the tration commonly exceeds 1 mg/L. Contamination of the southwest (fig. 1) (Davis and others, 1973, p. 31). Water in aquifer by wastes from industrial sites and from landfills and the aquifers is confined and stands at relatively shallow depths septic tank systems in urban areas poses the most serious in wells. Wells capable of yielding more than 1,000 gallons per water-quality-related problem. High ground-water levels are a minute (gal/min) can be constructed in most of the Coastal potential problem in the Louisville area, where water levels are Plain province. Water from the aquifers generally contains just a few feet below structures in some places. less than 250 mg/L of dissolved solids and is soft. 224 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Kentucky [Mgal/d = millions of gallons per day; gal/min = gallons per minute; mg/L = milligrams per liter; ft = feet. Sources: Reports of the U.S. Geological Survey and Kentucky Geological Survey] Aquifer name and description Water withdrawals in 1980 Common (Mgal/d) range Well characteristics Depth (ft) Yield (gal/min) Remarks May Common May exceed range exceed Alluvial aquifer: Sand and gravel. Confined and unconfined. 115 50-125 140 25-500 Tertiary aquifers: Includes the Claiborne Group undivided and the Wilcox Formation. Mostly sand, silt, and clay. Confined except in outcrop area. Cretaceous aquifers: Includes the McNairy Formation. Mostly sand, silt, and clay. Confined except in outcrop area. Pennsylvanian sandstone aquifers: Sandstone, siltstone, and shale. Partly confined. 11.4 100-600 800 5-100 4.6 100-400 500 5-25 18.7 75-200 400 1-5 Mississippian limestone aquifers: Limestone and shale. Partly confined. Ordovician limestone aquifers: Limestone and shale. Partly confined. 17.9 100-400 500 2-10 14.4 50-200 300 2-10 5,000 Used as source or partial source for several municipal and industrial areas along Ohio River, including Owensboro, Hawesville, Branden- burg, Louisville, and Carrollton. Water generally hard to very hard and generally contains iron in excess of 1 mg/L. Aquifer is the coarse unconsolidated aquifer in Ohio, the glaciofluvial aquifer in Indiana, and terrace and alluvial sand aquifer in Tennessee. 1,200 Supplies water for several towns including Hickman, Mayfield, Fulton, and Clinton and several rural water districts. Water generally meets national drinking-water regulations. Aquifer is Tertiary Sands aquifer in Tennessee and the Claiborne aquifer in Missouri. 1,100 Supplies water for Murray, Benton, Reidland, and several rural water districts. Water generally meets national drinking-water regulations. Mica in sands may clog well screens in places. Aquifer is the Cretaceous sands aquifer in Tennessee and McNairy aquifer in Missouri. 200 Used mainly for domestic and stock supplies. Some used for small municipal and industrial supplies, and some used in coal washing and water flooding for secondary recovery of oil. Water generally contains iron in excess of 0.3 mg/L and may contain chloride concentrations in excess of 250 mg/L at depths less than 100ft. Aquifer is sandstone aquifer in Ohio and Upper and Lower Pennsylvanian aquifer in West Virginia. 500 Supplies water for Elizabethtown, Horse Cave, Park City, and several other small towns. Water generally hard; some deeper supplies contain hydrogen sulfide. 300 Supplies water mostly for domestic and stock use. Water generally hard. Some deeper supplies have chloride concentrations greater than 250 mg/L and may contain hydrogen sulfide. National Water Summary Kentucky 225 EXPLANATION Alluvial aquifer Tertiary and Cretaceous aquifers Pennsylvanjan sandstone aquifers Mississippian limestone aquifers jfgm Ordovicjan limestone aquifers A A' Trace of cross section 85° 84° 89° 50 100 MILES Sea level - -1000" Figure 1. Principal aquifers in Kentucky. A, Geographic distribution. 3, Physiographic diagram and divisions. C, Generalized cross section (A-A'). (See table 2 for a more detailed description of the aquifers. Sources: A, Reports in Selected References. B, Fenneman, 1938; McFarlan, 1943; Raisz, 1954. C, Compiled by R. J. Faust from U.S. Geological Survey files.) 226 National Water Summary Ground-Water Resources PENNSYLVANIAN SANDSTONE AQUIFERS The Pennsylvanian sandstone aquifers supply water mostly for domestic and stock use. In general, wells produce less than 5 gal/min, but wells in a few areas have produced about 200 gal/min (Maxwell and Devaul, 1962, p. 20). Water from Pennsylvanian sandstone aquifers generally contains iron in excess of 0.3 mg/L and may have chloride concentra- tions greater than 250 mg/L at depths of less than 100 feet in places (Price and others, 1962, p. 44). Some coal beds in the Pennsylvanian rocks also produce small quantities of water that may contain hydrogen sulfide. The production of coal, oil, and gas from the Pennsylvanian rocks affects the availa- bility and quality of ground water. Mining disrupts local ground-water flow systems. Drainage from mines can enter the ground-water system and increase concentrations of select- ed constituents, particularly trace elements, in the water. Oil and gas production in the State can yield quantities of brine that may enter the ground-water system if not disposed of properly. Also, brine may migrate upward through aban- doned and inadequately plugged wells to contaminate fresh- water zones in the aquifers. MlSSISSIPPIAN AND ORDOVICIAN LIMESTONE AQUIFERS The Mississippian and Ordovician limestone aquifers crop out over a large area of Kentucky (fig. 1). The aquifers supply water for several small towns and many domestic and stock users. Hardness as calcium carbonate and chloride concentration exceeds 250 mg/L in many supplies; hydrogen sulfide is present in some supplies (Brown and Lambert, 1963, p. 45; Palmquist and Hall, 1961, p. 27). Also, a significant potential for ground-water contamination exists where sink- holes and solution-formed openings facilitate the rapid infil- tration of contaminants from land surface to the ground- water system. Sinkholes can form quickly in the limestone aquifers and damage manmade structures. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS The distribution of ground-water withdrawals and trends of ground-water levels in Kentucky are summarized in figure 2. Most of the large pumping centers are in the alluvium along the Ohio River and in the Coastal Plain province. Water levels have remained relatively stable in most of the State during the period for which records are available. One exception is the Louisville area (location 10, fig. 2) where intensive pumping and less-than-average rainfall caused a decline in water levels during the 1940's. Decreased pumping and greater-than-average precipitation caused a large water- level rise during the 1970's. In recent years, water levels have remained relatively constant except for seasonal fluctuations. GROUND-WATER MANAGEMENT A number of State agencies within the Department of Mines and Minerals and the Kentucky Cabinets of Human Resources and Natural Resources and Environmental Protec- tion are responsible for comprehensive ground-water manage- ment. Specific State legislation and regulations that relate to ground-water protection or management are discussed below. Water Quality Standards (401 Kentucky Administrative Regulation No. 5:031). Specific water-quality standards are established for aquatic life, domestic-water-supply use, recrea- tional use, and outstanding resource waters (wild and scenic areas, nature preserves, etc.). Water Resources Laws (Kentucky Revised Statutes, Chapter 151). Under provisions of this statute, a consumptive user of public water (except for agricultural uses, steam- generating plants, and domestic users) is required to obtain a permit from the Natural Resources and Environmental Pro- tection Cabinet to withdraw 10,000 gallons per day or more. Control of Water Pollution from Oil and Gas Facilities (401 Kentucky Administrative Regulation 5:090). Permits for the construction and operation of disposal wells for brine reinjection are obtained through the Division of Water. Liners are required for brine-holding pits, and brine injection is allowed only into geologically isolated formations having dissolved-solids concentrations greater than 10,000 parts per million (approximately 10,000 mg/L) of dissolved solids or into those formations that meet the requirements of exempted aquifers as established by the U.S. Environmental Protection Agency (40 CFR 146.4). Permanent Program Regulations for Surface Coal Min- ing and Reclamation Operations and Coal Exploration Opera- tions (405 Kentucky Administrative Regulation Chapters 8 through 24). The protection of ground-water quality and recharge capacity associated with surface and underground mining activities are addressed. Waste Management Regulations (401 Kentucky Adminis- trative Regulation Chapter 30). Solid- and hazardous-waste management regulations are administered by the Division of Waste Management. Performance standards for waste-dis- posal sites, including the protection of a ground-water con- tamination, are part of this responsibility. Subsurface Sewage Disposal Regulations (815 Kentucky Administrative Regulation 20:141 and 20:160). These regula- tions specify such standards as the minimum size and capacity of private subsurface sewage-disposal systems and the mini- mum distance from the systems to drinking-water wells. Permits are issued from the Division of Consumer Health Protection, Cabinet for Human Resources. Oil and Gas Regulations (805 Kentucky Administrative Regulation 1:020, 1:060, and 1:070). Plugging, casing, and operation of wells are accomplished in accordance with the regulations established by the Department of Mines and Min- erals. Unreasonable damage to underground water supplies from waste oil and gas is prohibited. In addition to the above State activities, the Kentucky Geological Survey is responsible for the maintenance of a statewide water-data network and the investigation of the State's water resources. These responsibilities are accom- plished in cooperation with the U.S. Geological Survey. The research, data collection, and analysis provided by this coop- erative program form an information base upon which ground-water-management decisions are made by appropriate State agencies. The U.S. Geological Survey also cooperates with other State and local agencies in studies of selected areas. National Water Summary Kentucky 227 2 Tertiary aquifer Confined I I I I I I I I I 1955 1965 1985 O 1 V 1 20 g 30 3 40 3 50 i_ 60 S 70 ^ 80 o 90 f 100 UJ 5 Alluvial aquifer Confined - - /x/vv^ ^S>v'Vx/_^-v/» - : i i i i i i i i i EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) O 1.0-5 O 5,1 - 10 £) Greater than 10 Location number O Withdrawal sits 1935 1945 1965 J975 1985 o2 i3 § to £C Ie 0.s i« 14 16 18 20 22 24 26 28 30 ~ 7 Mississippian Unconfined limestone aquifer ^ , : V>WT - _ _ - i i i i i i i i i 1935 1945 1955 1965 1975 19! 10 Alluvial aquifer Confined Missingrecord^ I I I I I I I I I 14 PennsyK/anian sandstone aquifer Unconfined 1945 1965 1975 1985 1935 1945 1955 1965 1975 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Geographic area Calvert City .... Brandenburg. . . . Aquifer ... .do ............ Alluvial. ........... Alluvial. ........... ... .do ............ Mississippian limestone. . . ... .do ............ ... .do ............ ... .do ............ ... .do ............ ... .do ............ Pennsylvanian sandstone . . Principal uses Public supply. Industrial, public supply. Industrial. Public supply. Industrial, public supply. Do. Public supply. Do. Industrial, public supply. Industrial. Public supply. Industrial, public supply. Do. Industrial. Figure 2. Area! distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Kentucky. (Sources: Withdrawal data from Mull and Lee, 1984; water-level data from U.S. Geological Survey files.) 228 National Water Summary Ground-Water Resources SELECTED REFERENCES In addition to reports listed below, hydrologic and geologic information is available from the series of Bulletins, Water Resources Basic-Data Reports, and Reports of Investi- gations prepared cooperatively by the U.S Geological Survey and the Kentucky Geological Survey. Boswell, E. H., and others, 1965, Cretaceous aquifers in the Mississip- pi embayment: U.S. Geological Survey Professional Paper 448-C, p. C1-C37. Brown, R. F., and Lambert, T. W., 1963, Reconnaissance of ground- water resources in the Mississippian Plateau region, Kentucky: U.S. Geological Survey Water-Supply Paper 1603, 58 p. Davis, R. W. Lambert, T. W., and Hansen, A. J., Jr., 1973, Subsurface geology and ground-water resources of the Jackson Purchase region, Kentucky: U.S. Geological Survey Water- Supply Paper 1987, 66 p. Faust, R. J., Banfield, G. R., and Willinger, G. A., 1980, A compila- tion of ground water quality data for Kentucky: U.S. Geological Survey Open-File Report 80-685, 963 p. Fenneman, N. M., 1938, Physiography of Eastern United States: New York, McGraw-Hill Book Co., 714 p. Gallaher, J. T., and Price, W. E., Jr., 1965, Hydrology of the alluvial deposits in the Ohio River valley in Kentucky: U.S. Geological Survey Water-Supply Paper 1818, 80 p. Hosman, R. L., Long, A. T., Lambert, T. W., and others, 1968, Tertiary aquifers in the Mississippi embayment: U.S. Geological Survey Professional Paper 448-D, p. D1-D29. Maxwell, B. W., and Devaul, R. W. 1962, Reconnaissance of ground-water resources in the Western Coal Field region, Ken- tucky: U.S. Geological Survey Water-Supply Paper 1599, 34 p. McFarlan, A. C., 1943, Geology of Kentucky: Lexington, University of Kentucky, 531 p. (Reprinted 1961, Kentucky Department Economic Development). Mull, D. S., and Lee, V. D., 1984, Water use in Kentucky, 1980: Kentucky Natural Resource and Environmental Protection Cabi- net, DEP 1011. [Map] Palmquist, W. N., Jr., and Hall, F. R., 1961, Reconnaissance of ground-water resources in the Blue Grass region, Kentucky: U.S. Geological Survey Water-Supply Paper 1533, 39 p. Price, W. E., Jr., Mull, D. S., and Kilburn, Chabot, 1962, Reconnais- sance of ground-water resources in the Eastern Coal Field region, Kentucky: U.S. Geological Survey Water-Supply Paper 1607, 56 p. Raisz, E., 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C..U.S. Geological Survey, 417 p. Prepared by Robert J. Faust For further information contact District Chief, U.S. Geological Survey, Federal Building, Room 572, 600 Federal Place, Louisville, KY 40202 U.S. National Water Summary Louisiana 229 LOUISIANA Ground-Water Resources Table 1. Ground-water facts for Louisiana [Withdrawal data rounded to two significant figures and may not add to totals because of independent founding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Walter, 1982] Population served by ground water, 1980 Louisiana has abundant ground-water resources. Ground water is available in most of the State in quantity and quality suitable for one or more of the major-use categories. Ground water provides about one-half of the irrigation sup- plies (the largest category of water use) and 44 percent of the _________ public-supply withdrawals (table 1). Ground water is the Number (thousands) - ----------------- 2,889 source for about 85 percent of all public-supply systems, for Percentage of total population -------------- 69 most industries (at least in part), and for virtually all rural ¥m^^^^!y^: _ ........... It850 users. In many areas of the State, aquifers can supply water Percentage of total population- ------------'44 for various uses, and wells of many public-supply systems From rural self-supplied systems: yield water that can be distributed with little or no treatment. Number (thousands) - --------------- 1,039 Percentage of total population- ------------ 25 OCTTI ^ _________Freshwater withdrawals, 1980_________ Surface water and ground water, total (Mgal/d) ----- 12,000 Louisiana, situated in the Gulf Coastal Plain, is underlain Ground water only (Mgal/d) -------------- 1,800 by thick sequences of unconsolidated sedimentary deposits of Percentage of total- ----------------- 14 , j i »u »* j «. -f j i j-i* Percentage of total excluding withdrawals for sand and gravel that form productive aquifers and clay and silt thermoelectric power ---------------- 27 that form confining beds. The prevailing dip of the deposits is ~ T~ southerly. The regional aquifers range in age from Pleistocene to Palencene Public-supply withdrawals: toFaieocene. ,_,,_,_ Ground water (Mgal/d)- --------------- 270 Water in the aquifers generally is confined, although Percentage of total ground water- ----------- 15 water commonly is under water-table conditions in outcrop Percentage of total public supply- ----------- 44 areas. Wells in some deep aquifers in south-central and D Per capita (gal/d) ------------------ 144 ^ M Rural-supply withdrawals: southeastern Louisiana flow at the land surface. In general, Domestic: under natural conditions, water in the aquifers moves in a Ground water (Mgal/d)- -------------- 54 southerly direction and toward major stream valleys. How- Percentage of total ground water - ----------- 3 , . . Percentage of total rural domestic ---------- 100 ever, intensive pumping that creates depressions in the potenti- Per capita (gal/d) ----------------- 52 ometric (water-level) surface alters the natural flow system Livestock: locally. Recharge is supplied by rainfall on outcrop areas, by Ground water (Mgal/d)- - ------------- 13 ,. . . , . . -r i i * i Percentage of total ground water - ----------- 1 seepage from streams, and by mteraquifer leakage. Annual Percentage of total livestock - ------------ 70 recharge rates range from about 1 to 12 inches (in.). Average Industrial self-supplied withdrawals: annual rainfall in areas where aquifers are recharged ranges Ground water (Mgal/d)- --------------- 460 from 45 to 60 in. Discharge of water from shallow aquifers ^Seof'illSZriaT^upplM: ------- * sustains the low flow of streams in Louisiana. Including withdrawals for thermoelectric power ----- 5 Freshwater is present to depths ranging from about 100 Excluding withdrawals for thermoelectric power - - - - 12 feet (ft) in the coastal areas to about 3,500 ft in parts of Ilri?SSrfJ£SoSu/d)- --------------- 990 south-central Louisiana (Rollo, 1960). Saline water is present Percentage of total ground water- ----------- 55 at some depth downdip in most aquifers, and, in southern Percentage of total irrigation ------------- 47 Louisiana, aquifers that contain saline water may be located between aquifers that contain freshwater. Ground-water temperatures range from about 65 °F for shallow aquifers in the north to about 100°F for the deepest aquifers in south-central Louisiana. The temperatures tend to be constant at specific depths and increase at a rate of about ALLUVIAL AQUIFERS 1°F for each 100 ft of depth. . , * j ,- ^ « j , f u The alluvial aquifers underlie the flood plains of the Mississippi, Red, and Ouachita River valleys. The alluvial PRINCIPAL AQUIFERS deposits typically consist of a confining layer of clay and silt The principal aquifers of Louisiana fall into five major that overlies sand and gravel. The aquifers generally thicken aquifer groups. In order from youngest to oldest, the aquifer southward; the base of the aquifer is about 100 ft below land groups are alluvial, Pleistocene, Pliocene-Miocene, Cockfield surface in the north to 250 to 450 ft below land surface in the and Sparta, and Wilcox-Carrizo. These aquifers are described south. The Mississippi River alluvial aquifer is the largest below and in table 2; their areal distribution is shown in figure yielding unit; well yields are as much as about 7,000 gallons 1. per minute (gal/min). The alluvial aquifers are not developed 230 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Louisiana [Mgal/d = million gallons per day; ft = feet; gal/min = gallons per minute; mg/L = milligrams per liter. Sources: Reports of the U.S. Geological Survey and Louisiana Office of Public Works.] Aquifer name and description Water withdrawals Well characteristics Depth (ft) Yield (gal/min) Remarks in 1980 Common May Common May (Mgal/d) range exceed range exceed Alluvial aquifers: Fine to medium sand near the top, grading to coarse sand and gravel near the base. Generally confined. 271 100-250 400 500-2,500 Pleistocene aquifers: Terrace aquifers: Fine sand near the top grading to coarse sand and cobble gravel near the base. Generally unconfined but may be confined locally. Chicot aquifer: Includes the Lake Charles "200-foot," "500-foot," and "700-foot" sands, and "upper" and "lower" sand units. Thick beds of sand and gravel divided by beds of silt and clay to the south. Confined except in and near the outcrop area. The "400-foot" and "600-foot" sands (at Baton Rouge) and upper Ponchatoula and Gonzales-New Orleans aquifers: Fine to coarse sand, some gravel. Generally confined. Pliocene-Miocene aquifers: Evangeline, upper Jasper, lower Jasper, Catahoula aquifers: Fine to coarse sand, locally some gravel; interbedded with silt and clay. Generally confined. The " 1,200-foot" and deeper sands in Baton Rouge area and lower Ponchatoula and deeper aquifers in southeastern Louisiana (not shown in figure 1): Fine to coarse sand. Confined. Cockfield and Sparta aquifers:Fine to medium sand interbedded with silt and clay; some indurated layers. Generally confined. 50-150 200 40-400 995 50-800 1,000 500-2,500 126 100-800 1,000 500-1,000 299 200-2,200 2,800 200-1,200 800-2,800 3,300 500-1,500 76 200-900 2,000 50-1,800 Wilcox-Carrizo aquifer:Sand, very fine to medium; silty in many places. Thin interbeds of clay, silt, and lignite. Some indurated layers. Generally confined. 10 100-600 800 40-150 7,000 Mississippi, Red, and Ouachita River valleys. Water generally hard to very hard and contains large concentrations of iron. Sulfate concentrations large locally in Red River valley. Local areas of very saline water in Red River and upper Mississippi River valleys. Contain only saline water in coastal areas. Major use is for irrigation and industry. 1,000 Northern and central Louisiana. Saturated thickness variable. Water soft in some areas, hard in other areas. pH typically low. Surface disposal of wastes is potential for contamination. Major uses rural and domestic. Grouped with alluvial aquifers in Arkansas. 4,000 Southwestern Louisiana. Iron concentra- tion generally exceeds 1.0 mg/L and hardness ranges from 10 to 250 mg/L as calcium carbonate. Local salinity prob- lems in coastal area, but some units contain freshwater to coastline. Primary aquifer for 13 southwestern parishes where it is intensively pumped for irrigation. 2,500 Southeastern Louisiana. Water ranges from soft to hard; small to large iron concentration. Primary use is industrial. Extensive cones of depression in New Orleans and Baton Rouge areas due to industrial pumping. Equivalent to Citronelle aquifer in Mississippi. Withdrawals (126 Mgal/d) include those from the terrace aquifers. 3,000 Southwestern, western, and central Louisiana. Water generally soft with small to moderate amounts of iron. Locally color and fluoride may be excessive for public-supply use. Annual water-level declines in wells in some intensively pumped units are 1 to 2 ft. 4,000 Southeastern Louisiana.Generally underlies Pleistocene aquifers. Water soft and of good quality for water-supply use; may have large iron concentrations locally. Extensively developed for public-supply and industrial use. 2,500 In western part of State, a few wells are as deep as 2,200 ft in Cockfield and 1,600 ft in Sparta. Water generally soft. Locally, water may have a large iron concentration. Sparta intensively pumped for industrial and public-supply use in northern Louisiana; extensive cone of depression extends into Arkan-. sas. Annual water-level declines of 1 to 3 ft in wells in Sparta. 350 Water soft to moderately hard; locally, large iron concentrations. Used for local public supplies and domestic use. Equivalent to Carrizo-Wilcox aquifer in Texas. 33- National Water Summary Louisiana EXPLANATION I __ Alluvial aquifers Pleistocene aquifers Pliocene-Miocene aquifers Cockfield and Sparta aquifers ^^1 Wilcox-Carrizo aquifer Areas where no freshwater occurs at any depth A A' Trace of cross section 231 Figure 1. Principal aquifers in Louisiana. A, Geographic distribution. B, Physiographic diagram. C, Generalized cross section (A-A'). (See table 2 for a more detailed description of the aquifers. Sources: A, G. T. Cardwell, H. C. McWreath III, and J. E. Rogers. B, Raisz, 1954. C, compiled by G. T. Cardwell from U. S. Geological Survey files.) 232 National Water Summary Ground-Water Resources extensively, but the water is ideal for irrigation. The water is hard to very hard [200-450 milligrams per liter (mg/L) as calcium carbonate] and typically has high concentrations of iron (exceeding 1 mg/L). Slightly saline water in local areas in the Red and Mississippi River valleys may be the result of pollution by oil-field brines (Whitfield, 1975a, 1980). PLEISTOCENE AQUIFERS The Pleistocene aquifers are principal sources of freshwa- ter in central, southwestern, and southeastern Louisiana. In central Louisiana, the terrace aquifers are important, though of limited potential. The aquifers range in depth from 50 to 200 ft. Saturated thickness ranges from 0 to 110 ft. Well yields range from 40 to 400 gal/min; potential yields are as much as 1,000 gal/min (Snider and Sanford, 1981). Typically, the water has a small concentration of dissolved solids (less than 150 mg/L), low pH (less than 6), and is soft (less than 60 mg/L as calcium carbonate). The Pleistocene Chicot aquifer, which is the principal aquifer in southwestern Louisiana and is the most intensively pumped aquifer, provides about 56 percent of the total ground-water withdrawals in the State (Walter, 1982). Aqui- fer depths range from about 50 ft in northern outcrop areas to 800 to 1,000 ft in the coastal area. Typical depths of irrigation wells are 200 to 300 ft; public-supply wells at Lake Charles are about 700 ft deep. Irrigation wells yield as much as 4,000 gal/min from massive sands that may exceed several hundred feet in thickness. To the north, the water is hard (greater than 150 mg/L as calcium carbonate) but is suitable for irrigation; to the south, deeper sands yield soft (less than 60 mg/L as calcium carbonate) water of excellent quality for public-sup- ply use. In southeastern Louisiana, the Pleistocene aquifers range in depth from a few hundred feet to more than 1,000 ft and contain freshwater to depths of 700 to 800 ft in the southern oart of the area. Principal individual aquifers are the "400-foot" and "600-foot" sands at Baton Rouge, the Gon- zales-New Orleans aquifer (principal source in New Orleans), and the upper Ponchatoula aquifer. Individual sand units are commonly 50 to 150 ft thick and yield 500 to 1,000 gal/min of potable water. Principal problems with the Pleistocene aquifers are (1) the limited production capacity of the terrace aquifers locally, (2) local saltwater problems in the Chicot aquifer, including encroachment in local coastal areas (Harder and others, 1967; Nyman, 1984), and (3) saltwater encroachment in the "600-foot" sand at Baton Rouge (Whiteman, 1979) and in the Gonzales-New Orleans aquifer (Rollo, 1966). Potential con- tamination from surface disposal of wastes is also a concern in some areas. PLIOCENE-MIOCENE AQUIFERS The Pliocene-Miocene aquifers form part of a large artesian basin in the western part of the Gulf Coastal Plain and supply potable water to many towns and cities. The Pliocene-Miocene aquifers include the Evangeline, Jasper, and Catahoula aquifers of central and southwestern Louisia- na; the sands below the "600-foot" aquifer in the Baton Rouge area; and deeper sands in southeastern Louisiana. These aquifers have been described in detail in southwestern Louisia- na by Whitfield (1975b) and in southeastern Louisiana by Nyman and Fayard (1978) and Buono (1983). In the Evangeline aquifer in southwestern Louisiana, freshwater extends to a maximum depth of about 2,200 ft; in the underlying Jasper aquifer, freshwater extends to about 3,400 ft. The total sand thickness available for development ranges from about 100 to 1,000 ft. Yields of wells range from several hundred gallons per minute to as much as 3,000 gal/min. In southeastern Louisiana, individual sands tend to be thicker and average yields greater than in other areas. Sands typically are 50 to 250 ft thick and yields are as much as 4,000 gal/min (Cardwell and others, 1967). Depth to the base of the freshwater section in south-eastern Louisiana ranges from about 2,000 to 3,400 ft. The deepest freshwater well (3,354 ft) in the State taps a Miocene aquifer in southeastern Louisiana (Nyman and Fayard, 1978). The principal problems pertaining to Pliocene-Miocene aquifers are local occurrences of large fluoride concentrations (greater than 2 mg/L), dark color (greater than 30 units), depletion of artesian head in intensively pumped areas (Torak and Whiteman, 1982), and local saltwater encroachment in the "1,500" foot and deeper sands of the Baton Rouge area (Whiteman, 1979). COCKFIELD AND SPARTA AQUIFERS The Cockfield and Sparta aquifers are important to water users in northern Louisiana the Cockfield principally in the northeast and the Sparta in the north-central part of the State. In much of the area where the Cockfield contains freshwater, it underlies the alluvial aquifer and generally yields water that is relatively soft compared to the hard water in the alluvium. Wells commonly range in depth from a few hundred feet to about 800 ft and yield from 50 to 500 gal/min. Water in the Cockfield typically has color greater than 30 units, a level that may be objectionable for public supply. The areally extensive Sparta aquifer is the principal source of supply in north-central Louisiana and adjacent sections of Arkansas. Well depths range from 200 ft or less in the outcrop area in northwestern Louisiana to common max- imum depths of about 900 ft, and well yields commonly range from 100 to 1,800 gal/min. Thickness of the aquifer is as much as 700 ft (Rogers and others, 1972). Freshwater in the Sparta aquifer is present to depths ranging from a few hun- dred feet to about 1,000 ft. The water generally is soft, and iron concentrations are variable but typically small (less than 0.3 mg/L) in the deeper sand units. The principal problem of the Sparta is declining water levels, with annual declines that range from 1 to 3 ft. Saltwater encroachment is a problem in the Monroe area. WILCOX-CARRIZO AQUIFER The Wilcox-Carrizo is the most important and areally extensive aquifer in northwestern Louisiana. However, the aquifer sands are typically thin and fine, which restricts well yields. Wells range in depth from about 100 to 600 ft, and typically wells yield from 40 to 150 gal/min and exceptional National Water Summary Louisiana 233 20 40 60 80 100 120 140 160 180 0 50 100 iso 200 250 300 350 400 450 ~ 2 Chicot aquifer Confined 1945 1955 1965 1975 J985 record .4 Pliocene-Miocene aquifer Confined 1935 1945 1955 1965 1975 1985 - 140 c 160 180 200 0 20 40 60 80 100 120 140 160 ISO 40 60 80 100 120 140 160 180 200 220 6 Chicot aquifer Confined 1945 1955 1965 1975 1985 13 Pleistocene aquifer Confined 1945 1955 1965 1975 1985 - 18 Pliocene-Miocene aquifer Confined I I I I I I I I I 1935 1945 1955 1965 1975 1985 EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) 10-49 50-99 100-200 Withdrawal site 23 O Hydrograph only 1 .OW LAND b LL. 1 1 80 100 120 140 180 200 220 260 19 ~ 23 Sparta aquifer Confined " __^^ I ^ -- - - - 35 1945 1955 1965 1975 1 9£ WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Geographic Acedia Perish ..... Jefferson Davls Perish. Evangallne Perish . . . Baton Rouge. ..... Alien Parish ...... Lake Charles. ..... Richland Parish .... Morehouse Perish . . . Calcasleu Parish .... East Carroll Parish . . Iberviile Parish. .... St. Lendry Parish . . . New Orleans. ..... Lafayette Perish .... Vermilion Parish . . . Bogelusa ........ De R idder ....... Alexandria ....... Concordla Perish . . . St. Martin Parish . . . West Monroe. ..... Jonesboro-Hodge . . . Aquifer Chicot ......... ... .do ......... ... .do ......... Pleistocene, Pliocene- Miocene. Chicot ......... ... .do ......... Alluvial. ........ ... .do ......... Chicot ......... Alluvial. ........ ... .do ......... Chicot ......... Chicot ......... ... .do ......... Pleistocene, Pliocene- Miocene. Pliocene-Miocene . . . Pleistocene, Pliocene- Miocene. Alluviei. ........ Chicot ......... Sparta ......... ... .do ......... Principal uses irrigation, aquacuiture. Do. Do. industrial, public supply. irrigation. Industrial, public supply. Irrigation, aquecuiture. Irrigation. Irrigation, Industrial. irrigation. industrial. irrigation. Industrial. Irrigation, public supply. irrigation. industrial, public supply. Industrial. Public supply. industrial. irrigation. irrigetion, aquacuiture. industrial, public supply. industrial. Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Louisiana. .(Sources: Withdrawal data from Walter, 1982; water-level data from U.S. Geological Survey files.) 234 National Water Summary Ground-Water Resources wells as much as 350 gal/min. Deepest freshwater is approxi- mately 800 ft. Water quality is somewhat variable but general- ly suitable for domestic and public-supply use. GROUND-WATER WITHDRAWALS AND WATER LEVEL TRENDS Although all major aquifer groups in Louisiana support some development, the Pleistocene aquifers are the most intensively pumped. In 1980, over 1.1 billion gallons per day was withdrawn from the Pleistocene aquifers; of this amount, 995 million gallons per day (Mgal/d) was pumped from the Chicot aquifer in southwestern Louisiana, mainly for irriga- tion (fig. 2). Water levels in wells in the Chicot have declined gradually (an annual average of about 1 ft) but, in recent years, the decline has ceased (locations 2 and 6, fig. 2). The hydrograph for location 6 reflects the effect of localized industrial pumping from the Chicot aquifer ("500-foot" sand) in the Lake Charles area. From 1973 to 1982, levels rose gradually because of decreases in pumping rates; in 1982, levels rose sharply when industrial ground-water withdrawals were reduced and augmented by surface water from the Sabine River. In southeastern Louisiana, water levels in wells in the "400-foot" and "600-foot" sands at Baton Rouge declined as much as several hundred feet from 1920 to about 1970 (Mor- gan, 1961) but have risen 40 to 50 ft since then. Water levels also have risen in wells in the Gonzales-New Orleans aquifer (one of the Pleistocene aquifers in southeastern Louisiana) at New Orleans (location 13, fig. 2). Water levels in the terrace aquifers typically reflect changes in seasonal withdrawals and variations in precipitation (Rogers, 1981). The shallow alluvial aquifers are connected hydraulically to major streams, and water levels generally reflect stream stages and effects of climatic cycles. In northeastern Louisia- na, local shallow cones of depression may develop in inten- sively pumped areas remote from stream sources of recharge. About 270 Mgal/d was pumped from the alluvial aquifers in 1980, mostly from the Mississippi River alluvial aquifer. The Pliocene-Miocene aquifer group is the second most intensively pumped (299 Mgal/d in 1980). Largest withdraw- als are made at Baton Rouge, Alexandria (location 18, fig. 2), and De Ridder. Major development of the Pliocene-Miocene aquifers occurred later than for other aquifers, primarily because they are relatively deeper at population centers. Water levels in wells in the "2,000-foot" sand at Baton Rouge, which is pumped intensively for industrial and public-supply uses, declined sharply until about 1973, when reductions of indus- trial pumping caused water levels to rise (location 4, fig. 2). However, water levels are declining at annual rates of as much as 2 ft in most other areas where water is obtained from Pliocene-Miocene aquifers. Water levels in wells in the Cockfield aquifer have not changed significantly, except for small declines in areas of relatively intensive development. However, levels in wells in the Sparta aquifer (fig. 2) show long-term declining trends dating back to about 1920. In 1980, 4 Mgal/d was pumped from the Cockfield and 72 Mgal/d from the Sparta aquifer (Walter, 1982). Although the Wilcox-Carrizo aquifer is areally extensive, only about 10 Mgal/d was pumped from it in 1980. Because the pumping is dispersed, no apparent regional water-level trends have developed, although local declining water-level trends are evident near pumping wells. GROUND-WATER MANAGEMENT Five different State agencies have active roles in adminis- tering ground-water activities in Louisiana. The Department of Transportation and Development's Office of Public Works (OPW) licenses and regulates drillers of water wells, monitor wells, geotechnical boreholes, and heat pump wells, as well as those engaged in plugging abandoned wells and boreholes. The OPW registers all water wells drilled in Louisiana and maintains an active computer file of these wells. The OPW also administers the Louisiana Water Resources Information Center, which has the responsibility of indexing all available water-resources information for the State. The Department is the major State agency participating with the U.S. Geological Survey in a cooperative ground-water program of data collec- tion, areal studies, and research. The Department of Natural Resources has certain regula- tory responsibilities relating to protection of ground water. The Department's Office of Conservation has jurisdiction over underground injection wells and also has regulatory functions relating to protection of ground water in areas of lignite mining and oil and gas development. The Louisiana Geological Survey maintains some ground-water functions, principally in support of the missions of the Department of Natural Resources and other State agencies. The Louisiana Department of Health and Human Re- sources has responsibility for ensuring that drinking-water supplies are safe and of good quality and also enforces construction standards for public-supply wells. The newly formed Department of Environmental Quality has responsi- bilities for monitoring and protecting ground water related to regulation of solid and hazardous waste. National Water Summary Louisiana 235 SELECTED REFERENCES Buono, Anthony, 1983, The Southern Hills regional aquifer system of southeastern Louisiana and southwestern Mississippi: U.S. Geo- logical Survey Water-Resources Investigations Report 83-4189, 38 p. Cardwell, G. T., Forbes, M. J., Jr., and Gaydos, M. W., 1967, Water resources of the Lake Pontchartrain area, Louisiana: Louisiana Geological Survey Water Resources Bulletin No. 12, 105 p. Harder, A. H., Kilburn, Chabot, Whitman, H. M., and Rogers, S. M., 1967, Effects of ground-water withdrawals on water levels and salt-water encroachment in southwestern Louisiana: Louisiana Geological Survey Water Resources Bulletin No. 10, 56 p. Long, R. A., 1965, Ground water in the Geismar-Gonzales area, Ascension Parish, Louisiana: Louisiana Geological Survey Wa- ter Resources Bulletin No. 7, 67 p. Morgan, C. O., 1961, Ground-water conditions in the Baton Rouge area, 1954-59, with special reference to increased pumpage: Louisiana Geological Survey Water Resources Bulletin No. 2, 78 p. Nyman, D. J., 1984, The occurrence of high concentrations of chloride in the Chicot aquifer system of southwestern Louisiana: Louisiana Department of Transportation and Development, Office of Public Works Water Resources Technical Report No. 33,51 p. Nyman, D. J., and Fayard, L. D., 1978, Ground-water resources of Tangipahoa and St. Tammany Parishes, southeastern Louisiana: Louisiana Department of Transportation and Development, Office of Public Works Water Resources Technical Report No. 15,76p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C..U.S. Geological Survey, 417 p. Rogers, J. E., 1981, Water resources of the Kisatchie well-field area near Alexandria, Louisiana: Louisiana Department of Tran- sportation and Development, Office of Public Works Water Resources Technical Report No. 26, 57 p. Rogers, J. E., Calandro, A. J., and Gaydos, M. W., 1972, Water resources of Ouachita Parish, Louisiana: Louisiana Geological Survey Water Resources Bulletin No. 14, 118 p. Rollo, J. R., 1960, Ground water in Louisiana: Louisiana Geological Survey Water Resources Bulletin No. 1, 84 p. __1966, Ground-water resources of the greater New Orleans area, Louisiana: Louisiana Geological Survey Water Resources Bulle- tin No. 9, 69 p. Ryals, G. N., 1982a, Regional geohydrology of the northern Louisia- na salt-dome basin; Part I, Conceptual model and data needs: U.S. Geological Survey Open-File Report 82-343, 23 p. __1982b, Ground-water resources of the Arcadia-Minden area, Louisiana: Louisiana Department of Transportation and Development, Office of Public Works Water Resources Techni- cal Report No. 28, 35 p. Sanford, T. H., Jr., 1973, Water resources of the Ruston area, Louisiana: Louisiana Department of Public Works Water Re- sources Technical Report No. 8, 32 p. Snider, J. L., and Sanford, T. H., Jr., 1981, Water resources of the terrace aquifers, central Louisiana: Louisiana Department of Transportation and Development, Office of Public Works Wa- ter Resources Technical Report No. 25, 48 p. Torak, L. J, and Whiteman, C. D., Jr., 1982, Applications of digital modeling for evaluating the ground-water resources of the "2,000-foot" sand of the Baton Rouge area, Louisiana: Louisia- na Department of Transportation and Development, Office of Public Works Water Resources Technical Report No. 27, 87 p. Walter, W. H., 1982, Pumpage of water in Louisiana, 1980: Louisia- na Department of Transportation and Development, Office of Public Works Special Report No. 3, 15 p. Whiteman, C. D., Jr., 1979, Saltwater encroachment in the "600-foot" and "1,500-foot" sands of the Baton Rouge area, Louisiana, 1966-78, including a discussion of saltwater in other sands: Louisiana Department of Transportation and Develop- ment, Office of Public Works Water Resources Technical Re- port No. 19, 49 p. Whitfield, M. S., Jr., 1975a, Geohydrology and water quality of the Mississippi River alluvial aquifer, northeastern Louisiana: Louisiana Department of Transportation and Development, Office of Public Works Water Resources Technical Report No. 10, 29 p. __1975b, Geohydrology of the Evangeline and Jasper aquifers of southwestern Louisiana: Louisiana Geological Survey Water Resources Bulletin No. 20, 72 p. __1980, Chemical character of water in the Red River alluvial aquifer, Louisiana: U.S. Geological Survey Water-Resources Investigations Open-File Report 80-1018, 95 p. Prepared by George T. Cardwell, Harry C. McWreath, III, and James E. Rogers For further information contact District Chief, U.S. Geological Survey, P.O. Box 66492, Baton Rouge, LA 70896 236 National Water Summary Ground-Water Resources U.S. Geological Survey Water-Supply Paper 2275 MAINE Ground-Water Resources National Water Summary Maine 237 Table 1. Ground-water facts for Maine [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Population data from U.S. Bureau of the Census, 1983, and Maine Ground Water Quantity Subcommittee, 1980; withdrawal data from Sol- ley, Chase, and Mann, 1983] Population served by ground water, 1980 Ground water is a vital natural resource in Maine. Although ground water comprises less than 10 percent of the total freshwater withdrawals in the State, it is the source of water for 57 percent of the population; the rural population is almost entirely dependent on ground water. Industry and livestock supply are the other major users of ground water. Ground-water withdrawals, water-use information, and relat- ed statistics are given in table 1. The distribution of ground- water withdrawals is associated with the location of popula- Number (thousands) ------------------- 642 tion centers. The greatest amount of pumping occurs in Percentage of total population -------------- 57 southwestern and coastal Maine with other ground-water From public water-supply systems: withdrawals located near the large towns in central and Number (thousands) - ---------------- 135 +v. \jir.- *. Percentage of total population- ------------ 12 northern Maine. From rural self-supplied systems: The quality of ground water is suitable for most uses. Number (thousands) ----------------- 507 However, local contamination of aquifers has occurred from Percentage of total population- ------------ 45 point sources, such as gasoline-storage tanks, salt-storage Freshwater withdrawals, 1980 sites, industrial subsurface disposal systems, septic systems, - - - - ^ slndee disnosal sites and solid waste landfills and from Surface water and ground water, total (Mgal/d) ------- 850 sludge-disposal sites and solid-waste landims, and trom Ground water only (Mgal/d) --------------- 80 nonpomt sources, such as highway deicmg salts and agncul- Percentage of total- ------------------ 9 tural practices. In some localities, increased concentrations of Percentage of total excluding withdrawals for naturally occurring iron and manganese in ground water are thermoelectric power ---------------- 1Q severe enough to limit the use of the water unless it is treated. Category of use In water from some crystalline bedrock aquifers, large concen- n ... : rr-: : c ,, . .- j 111 u Public-supply withdrawals: trations of naturally-occurring radioactive radon-222 have Ground water (Mgal/d)- --------------- 20 been observed, frequently exceeding 10,000 picocuries per liter Percentage of total ground water- ----------- 25 (pCi/L). Percentage of total public supply- ----------- 19 Per capita (gal/d) ------------------ 148 GENERAL SETTING Rural-supply withdrawals: Maine lies in the New England physiographic province of °Ground water (Mgal/d)- -------------- 26 the Appalachian Highlands (Fenneman, 1938). Within the Percentage of total ground water - ---------- 32 province are three divisions the Seaboard Lowland, the New Percentage of total rural domestic ---------- 98 England Upland, and the White Mountain Section. The Per capita (gal/d) ----------------- 51 topography is diverse, ranging from coastal plains in south- Livestock: .,.,. , ^ 6 \: . r 6 . * .. Ground water (Mgal/d)- -------------- 1.0 western Maine to mountainous regions in the northwestern Percentage of total ground water- ----------- 1 part of the State. Many surficial features of the State were Percentage of total livestock - ------------ 59 formed or modified during Pleistocene glaciation when out- Industrial self-supplied withdrawals: wash, ice-contact, and till deposits mantled the bedrock in a Ground water (Mgal/d)- --------------- 34 large part of the State. Percentage of total ground water- - - - - ------- 42 Generally, precipitation is sufficient to replenish the VtS^!S£SS^£SS^ vm ----- 5 water pumped from Maine's aquifers. Annual precipitation Excluding withdrawals for thermoelectric power ----- 5 ranges from about 34 inches (in.) in the northeast to 55 in. in Irrigation withdrawals: the northwest and north-central mountains and averages Ground water (Mgal/d)- --------------- .2 about 42 in. statewide (Knox and Nordenson, 1955). Water- Percentage of total ground water- ----------- .2 level records show that water tables may have large annual Percentage of total irrigation ------------- 3.3 fluctuations in response to climatic conditions, but the long- term depths to water remain relatively stable. A detailed study of the hydrology of the glaciofluvial aquifer in the little types based on hydrogeologic characteristics carbonate and Androscoggin River valley indicated that about 45 percent of crystalline bedrock. The characteristics of the glaciofluvial precipitation recharges stratified sand and gravel aquifers, and bedrock aquifers are described below and in table 2, from whereas only 20 percent or less of precipitation recharges till youngest to oldest; their areal distribution is shown in figure 1. (Morrissey, 1983). GLACIOFLUVIAL AND TILL AQUIFERS PRINCIPAL AQUIFERS The glaciofluvial aquifer is composed of unconsolidated Two principal types of aquifers underlie Maine uncon- outwash and ice-contact deposits. The unconsolidated glacio- solidated glacial deposits and bedrock composed of sedimen- fluvial deposits, which consist largely of sand and gravel, are tary, igneous, and metamorphic rocks. Bedrock in Maine is the most favorable for development of large water-supply comprised of numerous rock types that have very complex wells. A saturated glaciofluvial deposit contains about 35 structures. However, the bedrock can be grouped into two percent water by volume. Outwash deposits were deposited by 238 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Maine [Gal/min = gallons per minute; ft = feet; < = less than. Source: Reports of the U.S. Geological Survey and Maine Geological Survey.] Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Glaciofluvial aquifer: Outwash deposits: Stratified sand and 35-120 gravel deposits in valley trains, outwash plains, or deltas. Percentage of gravel is greatest near ice-contact deposits and decreases seaward. Deposits contain some silt, clay, and cobbles. May overlie or interfinger with marine or glacial lake deposits. Generally unconfined. Ice-contact deposits: Deposits 35 - 140 consist of well to poorly stratified deposits of sand, gravel, and cobbles, with some silt, clay, and boulders. Because the deposits were laid down under a variety of conditions, the variation in texture, sorting, and internal structure is great. Deposits overlie bedrock or till. May be overlain by younger unconsolidated units, principally marine deposits. Generally unconfined. Till aquifer: Till is a heterogeneous 10-30 mixture of clay, silt, gravel, cobbles, and boulders deposited directly from glacial ice. Forms a fairly continuous cover of varying thickness over bedrock in upland areas and occurs beneath younger deposits and above bedrock in some of the lowland areas. Generally unconfined. Carbonate bedrock aquifer: This unit 20-800 consists of limestone, calcareous shale, and calcareous siltstone. May be confined locally. Crystalline bedrock aquifer: This unit 20-800 consists of a variety of igneous and metamorphic rocks. Igneous rocks include granite, gabbro, diorite, granodiorite, and pegmatite and metamorphic rocks include schist, gneiss, quartzite, slate, and argillite. Locally confined at depth. 10 - 100 2,000 Yield depends upon thickness and grain size of deposits; better yields where deposits are in hydraulic continuity with adjacent body of surface water for recharge. Water generally of good quality for most uses, but, in northern Maine, moderately hard. Large concentrations of iron and manganese commonly reported. 50 - 1,000 3,000 Generally, best source of large supplies of ground water. Yields depend upon thickness, sorting, and grain size of deposit. Better yields obtained where deposits are in hydraulic continuity with adjacent body of surface water for recharge. Associated landforms include kames, eskers, and crevasse fillings. Quality of water generally good for most uses. In some localities, large concentrations of iron and manganese severe enough to limit use with without treatment. Because of permeability and typically shallow water table, these deposits susceptible to contamination. < 1 20 Source of water for numerous dug or drilled domestic wells. Generally low permeability. Yields water to wells very slowly. Wells likely to become dry in late summer when water tables are low. Quality of water generally good. Excessive iron concentrations may be a problem and, in northern part of State, water moderately hard to hard. 10-30 600 Water contained primarily in secondary openings such as cleavage or bedding planes, joints, fractures, or solution openings. Carys Mills Formation, a bluish-gray limestone, is fairly widespread and constitutes principal calcareous aquifer. Water of good chemical quality for most uses but hard. 2-10 500 Crystalline bedrock dense and relatively impermeable and contains recoverable water in secondary openings such as joints, fractures, and bedding or cleavage planes. Chemical quality of water good for most uses. Concentrations of iron and manganese exceeding national drinking water regulations found in some wells. Large concentrations of radon 222 have been found in the water, primarily from wells finished in granite, pegmatite, and metamorphosed rocks. National Water Summary Maine 239 68° EXPLANATION n Glaciofluvial aquifer - Unconsolidated outwash and ice-contact deposits of sand and gravel Till aquifer -- Forms a fairly continuous cover over bedrock units Carbonate bedrock aquifer Crystalline bedrock aquifer 50 100 MILES 45 ENGLAND jJC- UPLAND ;&T- SECTION (ss I WHITE MOUNTAIN SECTION SEABOARD LOWLAND SECTION Figure 1. Principal aquifers in Maine. A, Geographic distribution. B, Physiographic diagram and divisions. C, Typical stratigraph- ic sequence. (See table 2 for more detailed descriptions of aquifers. Sources: A, Modified from Adamik, 1984. B, Fenneman, 1938; Raisz, 1954. C, Compiled by T. J. Maloney from U.S. Geological Survey files.) 240 National Water Summary Ground-Water Resources meltwater streams near the margin of the glacier. Many of the outwash deposits are interlayered with relatively impermeable marine silt and clay deposits that may confine the water. Ice-contact deposits formed as sand and gravel settled from the meltwater that flowed under or through the glacier. Ice-contact deposits generally are thicker than outwash depos- its. Outwash and ice-contact deposits fill most preglacial valleys, as shown by the elongated and discontinuous expo- sures of these aquifers in figure 1. These deposits are more common in coastal and central interior Maine but also are present in northeastern Maine along the valleys of major rivers. Most supply wells are located in deposits that have large saturated thicknesses and are recharged by surface water. The quality of water in outwash and ice-contact deposits generally is suitable for most uses. In northern Maine, the water is moderately hard to hard. In scattered localities throughout the State, concentrations of iron and manganese are large enough to limit use. A study of the aquifers in southwestern Maine found an average iron concentration of 1.2 milligrams per liter (mg/L) and an average manganese concentration of 0.42 mg/L. These deposits are susceptible to contamination because they are very permeable, and pollu- tants can percolate readily to the water table from the land surface (Tolman and others, 1983). Till is considered to be a major aquifer in Maine because of the large percentage of the population that relies upon it as a water source. Because yields are so small, the areal extent of till has not been illustrated in figure 1. The greatest expected yields from this aquifer [about 20 gallons per minute (gal/ min); table 2] are only large enough for domestic, livestock, or commercial supply. Because they are shallow, many wells in till become dry during drought. Till is the most common surficial unit in the State. It overlies crystalline and carbonate bedrock nearly everywhere and commonly underlies ice-con- tact and outwash deposits. Till, which generally forms a thin discontinuous cover over bedrock in the upland areas, may be several hundred feet thick in the valleys and at the edges of valleys. The quality of water from till is generally suitable for most uses, although locally high iron concentrations are a problem. In the northern part of the State, water from till is moderately hard to hard. A typical sequence which can be found in the preglacial valleys of southern Maine is illustrated in figure 1. The block diagram shows the bedrock covered by a layer of till. Thick ice-contact sand-and-gravel deposits overlie the till along the valley walls and through the center of the valley. Marine silt and clay overlie the till and the lower part of the ice-contact deposits. Outwash sand-and-gravel deposits overlie the ma- rine silt and clay and the upper part of the ice-contact depos- its. CARBONATE BEDROCK AQUIFER The carbonate bedrock aquifer in northeastern Maine consists of limestone, calcareous shale, and calcareous silt- stone (fig. 1). Generally, the aquifer is confined. Water yield from the aquifer depends primarily on the number of second- ary openings such as joints, fractures, bedding or cleavage planes, or solution openings. As indicated in table 2, the common yields from this aquifer range from 10 to 30 gal/min but may exceed 600 gal/min. Most wells completed in the aquifer were developed for domestic or farm use. Deep wells generally have the greatest yields. These large-yielding wells are used primarily for industrial or public supplies but also may be used for irrigation in some areas. The water quality in the carbonate bedrock aquifer is suitable for most uses, except that it is hard. CRYSTALLINE BEDROCK AQUIFER Crystalline bedrock underlies much of the State and is the most widespread aquifer. It consists of numerous igneous and metamorphic rock types. The hydraulic properties of these rock types are similar and are, therefore, considered to be part of a single aquifer. Water yield primarily depends on the number of secondary openings such as joints, fractures, and bedding or cleavage planes. Development of municipal or large industrial wells in crystalline bedrock generally is at- tempted only if no other source of ground- or surface-water supply is readily available because of the uncertainty of locating a highly fractured zone. Expected yields for crystalline bedrock wells range from 2 to 10 gal/min but may exceed 500 gal/min (table 2). The quality of water from these aquifers generally is suitable for most uses. Some water supplies are treated to remove iron and manganese. Wells drilled in coastal areas have yielded brack- ish or salty water (Prescott, 1973; Tepper, 1980). Also, a study by the University of Maine at Orono (Hess and others, 1979) found levels of radioactive radon-222 gas in excess of 10,000 pCi/L in water from wells completed in granite, pegmatite, and high-grade metamorphic rocks. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Areas of major ground-water withdrawals for public- water supply are shown in figure 2. All these withdrawals are from ice-contact or outwash sand-and-gravel deposits. Data are not available for industrial ground-water use, except that self-supplied industrial withdrawals are estimated to account for more than 40 percent of the total ground-water withdraw- als (table 1). Although most industrial wells are located in sand-and-gravel deposits, some large-yield wells (exceeding 400 gal/min) were developed in crystalline and carbonate bedrock (Prescott 1964,1970). Continuous water-level records that show the effects of pumping generally are not available in Maine. Where such water-level records are available, the data indicate that climate affects water-level changes to a greater degree than pumping stress. Long-term decline in the water levels of major aquifers has not been a problem in the State, because recharge from precipitation and surface water is sufficient to replenish water withdrawn. However, in southwestern coastal areas, water- supply shortages are beginning to occur as a result of the increasing demands of large summer tourist populations and a steadily increasing year-round population. Water-supply shortages are predicted for 57 percent of the towns in coastal Maine by the year 1990 (Caswell and Ludwig, 1978). The hydrographs in figure 2 represent annual, lowest recorded water-levels observed in the major sand-and-gravel aquifers of Maine. Although the annual low water-levels fluctuate, the long-term water levels in all three wells have remained fairly stable. The well near the Brunswick-Topsham area (location 9, fig 2) has the longest continuous record. The water level for this well was about the same at the end of 1983 as it was 10 years earlier. During this 10-year period, the range of water level was only about 6 to 7 feet. The peaks in the hydrographs correlate well with the increased precipitation. National Water Summary Maine 241 6 Ice-contact deposit aquifer Unconfined 1970 1075 1980 1985 EXPLANATION Ground-water withdrawals, 1980 O 0.6 - 1.0 O 1-1 - 2.0 O Greater than 2.0 Location number O Withdrawal site 12 O Hydrograph only 9 Outwash deposit aquifer Confined 1970 1975 1985 1" § 2O tj 30 |, £ 50 12 Ice-contact deposit aquifer Confined 1885 WITHDRAWAL SITES [Withdrawals are principally for public supply] No. on map 1 2 3 4 5 6 7 8 9 10 11 Geographic area Brunswick-Topsham area. Aquifer Ice-contact deposit. Do. Do. Do. Do. Do. Outwash and ice- contact deposit. Ice-contact deposit. Outwash deposit. Ice-contact deposit. Do. Figure 2. Area! distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Maine. (Sources: Withdrawal and water-level data from the U.S. Geological Survey.) 242 National Water Summary Ground-Water Resources GROUND-WATER MANAGEMENT Several State agencies presently have statutory responsi- bilities for ground-water protection and management. The Department of Conservation, through the Maine Geological Survey and the Land Use Regulation Commission, is responsi- ble for coordinating ground-water research, mapping ground-water availability, performing research into permit- related ground-water problems, and regulating activities that impact ground water in areas where population is sparse. The Department of Environmental Protection, through its Bureaus of Water, Land, and Oil and Hazardous Materi- als, is reponsible for reviewing and licensing activities that impact ground water. This Department also is responsible for research into the effects of gasoline leaks and pesticides on ground water and for ground-water-quality assessments and emergency response and cleanup. The Department of Human Services is involved with ground-water protection and management through its Drink- ing Water Program, Environmental Health Unit, and Public Health Laboratories. The Department is responsible for reviewing and approving new public water-supply sources, monitoring the quality of existing sources, performing re- search on ground-water-transmitted diseases, and performing water-quality analyses of private water supplies. The Maine Land and Water Resources Council is examin- ing the State's present statutes and regulations, agency pro- grams and manpower, and agency activities that pertain to ground water in an effort to ensure protection of public health and continued availability of ground water. SELECTED REFERENCES Adamik, J. T., 1984, Present and proposed ground water program for Maine: U.S. Geological Survey Water-Resources Investigations Report 84-4235, 43 p. Caswell, W. B., and Ludwig, Schuyler, 1978, Maine coastal area water supply and demand: Maine Geological Survey and State Planning Office, 244 p. Fenneman, N. M., 1938, Physiography of the eastern United States: New York McGraw-Hill Book Co., 714 p. Hess, C. T., and others, 1979, Radon-222 in potable water supplies in Maine The geology, hydrology, physics, and health effects: University of Maine at Orono, Land and Water Resources Center, 28 p. Knox, C. E., and Nordenson, T. J., 1955, Average annual runoff and precipitation in the New England-New York area: U.S. Geolog- ical Survey Hydrologic Investigations Atlas HA-7. Maine Ground Water Quantity Subcommittee, 1980, Assessment of ground-water quantity in Maine A report to the Ground Water Protection Commission: Ground-Water Protection Commis- sion, 19 p. Morrissey, D. J., 1983, Hydrology of the Little Androscoggin River valley aquifer, Oxford County, Maine: U.S. Geological Survey Water Resources Investigations Report 83-4018, 79 p. Prescott, G. C., Jr., 1964, Records of selected wells, springs, and test borings in the lower Penobscot River basin: U.S. Geological Survey open-file report, 40 p. __1967, Records of selected wells, springs, and test borings in the lower Androscoggin River basin: U.S. Geological Survey open- file report, 63 p. __1968, Records of selected wells, springs, and test holes in the lower Kennebec River basin: U.S. Geological Survey open-file report, 38 p. __1970, Records of selected wells, springs, and test holes in the lower Aroostook River basin, Maine: U.S. Geological Survey open-file report, 30 p. __1971a, Records of selected wells, springs, and test holes in the lower St. John River valley: U.S. Geological Surey open-file report, 22 p. __1971b, Records of selected wells and test holes in part of the Meduxnekeag River and Prestile Stream drainage basins: U.S. Geological Survey open-file report, 17 p. __1973, Records of selected wells, springs, and test holes in the southern Washington County area: U.S. Geological Survey open-file report, 40 p. __1976, Records of selected wells and test holes in the Windham- Freeport-Portland area of Cumberland County, Maine: U.S. Geological Survey open-file report, 48 p. __1979, Records of selected wells, springs, and test holes in the Royal, Upper Presumpscot and Upper Saco River basins, Maine: U.S. Geological Survey open-file report, 53 p. Prescott, G. C., Jr., and Drake, J. A., 1962, Records of selected wells and test holes, and springs in southwestern Maine: U.S. Geolog- ical Survey open-file report, 35 p. Prescott, G. C., Jr., and Attig, J. W., Jr., 1977, Geohydrology of part of the Androscoggin River basin, Maine: U.S. Geological Open-File Report 78-297, 54 p. Raisz, Erwin, 1954, Physiographic diagram, p. 54, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., and Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Tepper, D. H., 1980, Hydrogeologic setting and geochemistry of residual periglacial Pleistocene seawater in wells in Maine: Orono University of Maine, unpublished M.S. thesis, 126 p. Tolman, A. L., Tepper, D. H., Prescott, G. C., Jr., and Gammon, S. O., 1983, Hydrogeology of significant sand and gravel aqui- fers Northern York and southern Cumberland Counties, Maine: Maine Geological Survey [maps]. U.S. Bureau of the Census, 1984, Statistical abstract of the U.S.: 1983 (104th edition), Washington, D.C., 1015 p. Prepared by Thomas J. Maloney and Derrill J. Cowing For further information contact Chief, Maine Office, U.S. Geological Survey, 26 Ganneston Drive, Augusta, ME 04330 U.S. Geological Survey Water-Supply Paper 2275 National Water Summary Maryland and the District of Columbia 243 MARYLAND AND THE DISTRICT OF COLUMBIA Ground-Water Resources Table 1. Ground-water facts for Maryland and the District of Columbia [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Maryland- Herring, 1983; District of Columbia Solley, Chase, and Mann, 1983] Population served by ground water, 1980 MD D.C. Ground water is an abundant natural resource in Mary- land. Although it constitutes only 13 percent of total water used in the State, it is of substantial cultural and economic significance. The area east of Chesapeake Bay is dependent almost entirely on ground water for freshwater supplies. Maryland's aquifers provide water for nearly 1.3 million people (about 30 percent of the State's population) and for industry, irrigation, and other uses. In contrast, the District of Columbia depends mostly on surface-water supplies, al- though nearly 1 million gallons per day (Mgal/d) of ground water is used for industry. Ground water also is relied on for Number (thousands) ------------- 1,279 0 emergency backup for some hospitals, Government facilities, Percentage of total population --------- 30 0 and embassies Ground water was very important to the r^£*££3F'-'???- ------- '5<0 0 District of Columbia during its early years and was the sole Percentage of total population -------- 13 0 source of water until the city began to use surface water in From rural self-supplied systems: 1859 (Johnston, 1964, p. 42, 46). Ground-water withdrawals Number (thousands) - ------------ 739 0 in Maryland and the District of Columbia in 1980 for various Percentage of total population -------- n 0 uses are given in table 1. ___ Freshwater withdrawals, 1980_________ f* CM PDA I CCTTIMO Surface water and ground water, total (Mgal/d)- - 1,400 340 UtINtriAL C3tl II N<J Ground water only (Mgal/d) ---------- 175 0.8 Average annual precipitation, based on the 30-year peri- Percentage of total ------------- 13 0.2 od of record (1951-80), ranges from about 37 to 47 inches (in.) Percentage of total excluding withdrawals for in western Maryland and from about 42 to 47 in. in eastern thermoelectric power ----------- n Q.4 Maryland. In the District of Columbia, average annual _____________Category of use_____________ precipitation is about 43 in. Recharge rates vary, but, general- Public-supply withdrawals: ly, about one-fourth to one-third of precipitation reaches the Ground water (Mgal/d) ----------- 65 0 water table. A very small part of this ground water moves into Percentage of total ground water ------- 37 0 the deeper aquifers; most discharges to nearby streams and Percentage of total public supply ------- 9 0 provides about 50 to 70 percent of the flow of Maryland's ^SS^f^^k: ----------- streams. Domestic: Differing geologic features and landforms of the several Ground water (Mgal/d) ---------- 56 0 physiographic provinces of Maryland and the District of Percentage of total ground water ------ 32 0 Columbia cause significant differences in ground-water condi- Percentage of total rural domestic - ----- 100 0 tions from one part of the area to another. Physiographic LiveftS- 75 0 provinces of Maryland are the Coastal Plain, Piedmont, Blue Ground water (Mgal/d) ---------- 7 0 Ridge, Valley and Ridge, and Appalachian Plateaus (fig. 1). Percentage of total ground water ------ 4 0 Physiographic provinces of the District of Columbia are the Percentage of total livestock -------- 54 0 Coastal Plain and Piedmont. The Coastal Plain is underlain Industrial self-supplied withdrawals: by gently dipping unconsolidated strata. The Piedmont and ^m^oft'cXoindwa,V :::".:: % m* Blue Ridge are underlain by crystalline rock and consolidated Percentage of total industrial self-supplied: sedimentary units. Intensely folded and faulted consolidated Including withdrawals for thermoelectric power 6 0.6 sedimentary strata form the Valley and Ridge. These same Excluding withdrawals for thermoelectric power 18 57 strata are folded more gently in the Appalachian Plateaus. Irrigation withdrawals: Ground water (Mgal/d) ----------- 13 0 DPIM/^lDAi AniiiccDC Percentage of total ground water ------- 8 0 HKINUHAL AQUIFERS Percentage of total irrigation --------- 54 0 Aquifers in Maryland and the District of Columbia i , , « ~ ~n ~ ~r * j- * * * i-j * j -c Estimated from data in Maryland Department of Natural Resources and generally are Of two distinct types unconsolidated aquifers Maryland Department of Health and Mental Hygiene, 1983b. of the Coastal Plain and consolidated sedimentary and crystal- line aquifers of the other physiographic provinces (termed non-Coastal Plain aquifers). Principal aquifers and aquifer groups are described below and in table 2; their areal distribu- ing beds. These deposits are underlain by consolidated rock tion is shown in figure 1. The aquifer groups include aquifers similar to that of the Piedmont, at depths ranging from zero at and interbedded confining beds; the confining beds are not the Fall Line to about 8,000 feet at Ocean City. With the delineated in figure 1. exception of the Columbia aquifer, the Coastal Plain aquifers generally are confined except where exposed or where overlain COASTAL PLAIN AQUIFERS only by permeable surficial sediments. The unconsolidated deposits underlying the Coastal Plain The Columbia aquifer, which is the uppermost hy- form a southeastwardly thickening sequence that consists of drogeologic unit of the Coastal Plain in most of Maryland east sand-and-gravel aquifers interlayered with silt and clay confin- of Chesapeake Bay, is used as a principal water supply 244 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Maryland and the District of Columbia [Gal/min = gallons per minute; ft = feet; mg/L = milligrams per liter. Sources: Reports of the U.S. Geological Survey and Maryland Geological Survey.] Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Coastal Plain Aquifers: Columbia aquifer: Sand, gravel, 20 - 150 silt, clay, and slightly cemented gravelly sand. Generally unconfined. Aquifers in Chesapeake Group: Multi- 90-500 aquifer unit. Interbedded layers of sand, shells, gravel, silt, and clay. Generally confined. 50-500 1,500 A well in channel-fill gravel yielded 4,000 gal/min. Locally, water contains iron in excess of 0.3 mg/L. Nitrate contamination in some areas. Brackish water found in coastal areas. 10-400 1,000 Includes Pocomoke, Ocean City, Manokin, Frederica, Federalsburg, and Cheswold aquifers. Water contains iron in excess of 0.3 mg/L in some areas and generally is hard. Contains saltwater in some Piney Point aquifer: Sand, moderately 150-550 glauconitic, and interbedded layers of shells, silt, and clay. Confined. Aquia aquifer: Sand, glauconitic; 50 - 600 inter-bedded layers of silty clay and shells; cemented layers. Generally confined. Magothy aquifer: Sand and fine 100-900 gravel; interbedded thin layers of clay. Generally confined. Aquifers in Potomac Group: Multi- 30-1,250 aquifer unit. Interbedded lenses of sand, gravel, silt, and clay. Generally confined. Non-Coastal Plain Aquifers: Aquifers in Newark Group: Sandstone, 30-600 siltstone, shale, and conglomerate; some diabase dikes and sills. Unconfined to confined. Appalachian sedimentary aquifers: 30 - 400 Predominantly sandstone, shale, and siltstone; some limestone, dolomite and coal. Unconfined to confined. Carbonate aquifers: Limestone, 30-400 dolomite, and marble; some shale and quartzose limestone. Unconfined to confined. Piedmont and Blue Ridge crystalline 30 - 400 aquifers: Schist, gneiss, phyllite, and metamorphosed igneous units; some quartzite. Unconfined to partly confined. 10-250 600 Water hard (exceeds 120 mg/L of calcium carbonate) in some areas; slightly saline in downdip areas. 20 - 250 600 Iron concentrations exceed 0.3 mg/L in some areas. Locally, aquifer contains brackish water induced from Chesapeake Bay. 50 - 500 1,000 Iron concentration exceeds 0.3 mg/L, and pH less than 5.5 in some areas. Saltwater found in downdip areas. iOO - 1,000 2,000 Includes Patuxent and Patapsco aquifers and Potomac aquifer where undifferentiated. Large iron concentration (0.3 mg/L) and low pH present in some areas. Locally, contains brackish water induced from Chesapeake Bay and industrial pollutants. Saltwater found in downdip areas. 10-100 800 Water commonly hard; large iron and manganese concentrations in water from some wells; water from a few wells has a large sulfate concentration. 2-50 200 Hard water and large iron and manganese concentrations in water are common problems. Brine present at varying depths below 500 ft. Locally, water has low pH and large sulfate and iron concentrations related to coal mining. 5 - 200 500 Water generally hard; large iron and manganese concentrations in water are local problems. 2-60 200 Low pH of water from many units may affect pipes and appliances. Some water contains large iron and manganese concentrations. throughout that area. The approximate western limit of the aquifer is shown on the map in figure 1, and the relation of the aquifer to other Coastal Plain aquifers is indicated on the cross section. The aquifer generally is unconfined, but deeper zones locally are confined by clay layers. Thin surficial alluvium and terrace gravels are present elsewhere in Mary- land, but these are not commonly used for water supply and, thus, are not shown in figure 1. The aquifers in the Chesapeake Group are used mostly east of the Chesapeake Bay. These include the Cheswold, Federalsburg, and Frederica aquifers, which are used from Dorchester to Queen Annes Counties, and the Manokin, Ocean City, and Pocomoke aquifers, which are used in Somerset, Worcester, and Wicomico Counties. The Piney Point aquifer, which does not crop out, is tapped by wells in an area about 40 miles (mi) wide between Caroline and St. Marys Counties. The Aquia aquifer supplies water to an area about 50 mi wide between Kent and Queen Annes Counties in the northeast and Charles and St. Marys Counties in the southwest. The Magothy aquifer is used in a triangular area with corners in Cecil, Charles, and Dorchester Counties. Aquifers in the Potomac Group are used for water supply primarily north and west of Chesapeake Bay from Cecil to Charles Counties. From Baltimore County to Charles Coun- National Water Summary Maryland and the District of Columbia 245 79° EXPLANATION COASTAL PLAIN AQUIFERS Columbia aqu ifer - Surficial aqu ifer east of Chesapeake Bay Aquifers in Chesapeake Group Piney Point aquifer - Present only in subsurface Aquia aquifer Magothy aquifer Aquifers in Potomac Group Not a principal aquifer NON-COASTAL PLAIN AQUIFERS Aquifers in Newark Group Appalachian sedimentary aquifers I Carbonate aquifers I Piedmont and Blue Ridge crystalline aquifers A A' Trace of cross section 25 i 50 I 75 MILES Sea level - APPALACHIAN PLATEAUS BLUE RIDGE PROVINCE ^PIEDMONT PROVINCE COASTAU PLAIN Figure 1. Principal aquifers in Maryland and the District of Columbia. A, Geographic distribution. B, Physiographic diagram and divisions. C, Generalized cross section (A-A F). (See table 2 for a more detailed description of the aquifers. Sources: A, Otton and Richardson, 1958; Maryland Geological Survey, 1967; Cleaves and others, 1968; and Hansen, 1972. B, Raisz, 1954. C, compiled by L. J. McGreevy from U.S. Geological Survey files.) 246 National Water Summary Ground-Water Resources ty, the group includes the Patuxent and Patapsco aquifers. In Cecil and Hartford Counties, the aquifers are not differentiat- ed and are called the Potomac aquifer. The Patuxent and Patapsco aquifers are the only Coastal Plain aquifers used for water supply in the District of Columbia. Well yields of Coastal Plain aquifers depend on thickness and intergranular permeability of the sand and gravel layers and on well construction. Where permeable layers are suffi- ciently thick, well fields may produce several million gallons per day. Most Coastal Plain aquifers contain saltwater in downdip areas. Natural water quality generally is suitable for most uses; locally, however, excessive concentration of iron [0.3 milligrams per liter (mg/L)] may exist and the water can be hard (120 mg/L as calcium carbonate). The water may also be acidic in some areas with pH values as low as 5. In a few locations, aquifers have been contaminated from surface sources. The presence of saltwater in the Coastal Plain aquifers is discussed by Meisler (1981), Gushing and others (1973), and Hansen (1972). NON-COASTAL PLAIN AQUIFERS Aquifers of the Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateaus consist of consolidated sedimentary and crystalline rock. Well yields depend on the presence of open fractures, although a few sandstones have some inter- granular permeability. Well yields generally are small but may be as much as several hundred gallons per minute. Fracture openings in carbonate units (limestone, dolomite, and marble) commonly are enlarged by solution, and some wells that intercept enlarged openings have large yields. Aquifers in the Newark Group, the Appalachian sedimentary aquifers, and the carbonate aquifers generally are unconfined to partly confined in the upper hundred feet or so but may be confined at depth. The Piedmont and the Blue Ridge crystalline aqui- fers generally are unconfined to partly confined. Natural water quality generally is suitable for most uses. The most common problems are iron and manganese concen- trations, which sometimes exceed national drinking-water regulations (U.S. Environmental Protection Agency, 1982a,b); in some units, water hardness is in excess of 120 mg/L as calcium carbonate, and pH is less than 5. Brine underlies freshwater in the Appalachian sedimentary units but generally is at depths deeper than common drilling for ground-water wells. Locally, pollutants from surface sources have contaminated the ground water. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Major areas of ground-water withdrawals and trends of ground-water levels near selected pumping centers are shown in figure 2. All centers that produce more than 1 Mgal/d are in the Coastal Plain, with the exception of a quarry north of Baltimore (location 1, fig. 2). The largest concentration of pumping is near Baltimore and Annapolis. Pumping centers that produce from 0.1 to 1 Mgal/d are distributed throughout the State. Water levels generally decline in response to increases in pumping and recover as pumping is reduced. The hydro- graphs shown in figure 2 reflect the response of aquifers to pumping at selected withdrawal centers in the Maryland Coastal Plain. Increased pumping for private and public water supplies, powerplants, and military facilities has caused water levels to decline in the Aquia aquifer (location 10, fig. 2) and in the Magothy aquifer (location 8, fig. 2). Water levels in the Patuxent aquifer in the Glen Burnie area (location 4, fig. 2) have declined steadily since the mid-1950's in response to increasing withdrawals, principally for public supplies, from the Patuxent and Patapsco aquifers. Water levels in the Piney Point aquifer near Cambridge (location 15, fig. 2) have recovered in response to reduced pumping. Withdrawals from the Piney Point aquifer were reduced partly because new wells were drilled to tap other aquifers and partly because water use declined. Water levels in the Patapsco aquifer in the Baltimore area (location 3, fig. 2) also show recovery. There, pumping induced movement of brackish water from the Chesapeake Bay to the Patapsco aquifer. This caused wells in the Patapsco aquifer to be abandoned in favor of the deeper Patuxent aquifer. By contrast, little change in water level is noted in the hydrograph of a well in the Columbia aquifer near the major pumping center at Salisbury, Md. (location 16, fig. 2). The aquifer is unconfined, and the cone of depression caused by pumping diverts water from local streams; the diversion helps maintain ground-water levels, although streamflow may de- cline as a result. GROUND-WATER MANAGEMENT The District of Columbia relies mainly on surface water and has no specific legislation directed at ground-water man- agement. In Maryland, however, ground-water management and planning legislation are extensive. Two State-level organi- zations implement most of the regulatory, planning, and research programs. The Maryland Department of Health and Mental Hy- giene, through its Office of Environmental Programs, is responsible primarily for regulatory and operational programs with regard to water-quality aspects of ground-water manage- ment. As part of its responsibilities, the Office of Environ- mental Programs issues well-construction permits (Code of Maryland Regulation 10.17.13, implemented in 1945), re- quires well-completion reports from licensed well drillers, and regulates the disposal of water to the ground-water system (Health-Environmental Article, 9-3222). The Maryland Department of Natural Resources, through its agencies the Water Resources Administration and the Maryland Geological Survey, has a major role in ground- water-resource planning and management. The Water Re- sources Administration provides direction in the development, management, and conservation of the water of the State and regulates ground-water use through an appropriation-permit program (Natural Resources Article, 8-802, enacted in 1933). This program requires a permit to appropriate ground or surface water and requires water-use reports for withdrawals of 10,000 gallons per day or more. Domestic and farm users (including irrigation use) are exempt from these requirements. The Maryland Geological Survey is responsible for the mainte- nance of a statewide water-data network and the investigation of the State's water resources; these responsibilities are accom- plished in cooperation with the U.S. Geological Survey. The research, data collection, and analyses provided by this coop- erative program form an information base upon which ground-water management decisions are made by the Water Resources Administration. SELECTED REFERENCES In addition to reports listed below, hydrologic and geologic information was derived from the series of Bulletins, Water Resources Basic-Data Reports, and Reports of Investi- gations prepared cooperatively by the U.S. Geological Survey and the Maryland Geological Survey, and published by the Maryland Geological Survey. National Water Summary Maryland and the District of Columbia 247 30 §20 1'° 1 ° 10 4 Patuxent aquifer Confined Missing record J975 1985 «*u 30 20 10 0 10 20 30 40 50 ~ 16 Columbia aquifer - - - _ / y "~ ^~ Missing record - - I I I i Unconfined ___ x I I I 1945 Ground-water withdrawals, 1980 (million gallons per day) Location number 2 O Withdrawal site 1955 1965 1975 1985 3 Patapsco aquifer 1955 1975 10 Aquia aquifer Confined 60 70 80 90 too no 120 130 140 150 - 15 Piney Point aquifer Confined 1955 1975 1985 1945 1965 1985 WITHDRAWAL SITES No. on map 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Geographic araa Baltimore area. ...... Glen Burnie area ..... Chestertown araa ..... Ocean City area ...... Aquifer . . Patapsco, Patuxent ........ ... .do ............... . . Magothy .............. Piney Point ............ Federalsburg. ........... ... .do ............... Principal uses Industrial. Do. Do. Do. Do. Do. Do. Do. Figure 2. Area! distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Maryland and the District of Columbia. (Sources: Withdrawal data from Herring, 1983; Sol ley and others, 1983; water-level data from U.S. Geological Survey files.) 248 National Water Summary Ground-Water Resources Cleaves, E. T., Edwards, Jonathan, Jr., and Glaser, J. D., 1968, Geologic map of Maryland: Maryland Geological Survey Map. Cushing, E. M., Kantrowitz, I. H., and Taylor, K. R., 1973, Water resources of the Delmarva Peninsula: U.S. Geological Survey Professional Paper 822, 58 p. Edwards, Jonathan, Jr., 1981, A brief description of the geology of Maryland: Maryland Geological Survey, Miscellaneous Publica- tion, 1 p. Froelich, A. J., Hack, J. T., and Otton, E. G., 1980, Geologic and hydrologic map reports for land-use planning in the Baltimore- Washington urban area: U.S. Geological Survey Circular 806, 26 p. Hansen, H. J., 1972, A user's guide for the artesian aquifers of the Maryland Coastal Plain, Part 2, Aquifer characteristics: Mary- land Geological Survey, Miscellaneous Publication, 123 p. Herring, J. R., 1983, Maryland water withdrawal and use report 1980: Maryland Department of Natural Resources, Miscellaneous Publication, 50 p. Johnston, P. M., 1964, Geology and ground-water resources of Washington, D.C., and vicinity: U.S. Geological Survey Wa- ter-Supply Paper 1776, 97 p. Maryland Department of Natural Resources, 1982, The quantity and natural quality of ground water in Maryland: Maryland Depart- ment of Natural Resources, Water Resources Administration, Water Supply Division, 150 p. Maryland Department of Natural Resources and Maryland Depart- ment of Health and Mental Hygiene, 1983a, The water supplies of Maryland, Vol. I, Water supply management and conserva- tion A report to the General Assembly of Maryland in response to Joint Resolution No. 19 Laws of Maryland, 1981: Maryland Department of Natural Resources, 169 p. __1983b, Water supplies of Maryland, Vol. IV, The status of water supply development and potential water supply problems in Maryland A report to the General Assembly of Maryland in response to Joint Resolution No. 19 Laws of Maryland, 1981: Maryland Department of Natural Resources, 96 p. Maryland Geological Survey, 1967, Generalized geologic map of Maryland: Maryland Geological Survey Map, 1 sheet. Maryland State Planning Department, 1969, Ground-water aquifers and mineral commodities of Maryland: Maryland State Plan- ning Department Publication No. 152, 36 p. Meisler, Harold, 1981, Preliminary delineation of salty ground water in the northern Atlantic Coastal Plain: U.S. Geological Survey Open-File Report 81-71, 4 pi. Nutter, L. J., 1974, Well yields in the bedrock aquifers of Maryland: Maryland Geological Survey Information Circular 16, 24 p. Otton, E. G., and Richardson, C. A., 1958, Limestone aquifers of Maryland: Economic Geology, v. 53, p. 722-736. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001,56 p. Truitt, P. G., 1984, Maryland air and water quality atlas: Maryland Department of Health and Mental Hygiene, Office of Environ- mental Programs, 55 p. U.S. Environmental Protection Agency, 1982a, Maximum contami- nant levels (subpart B of part 141, National interim primary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100-149, revised as of July 1, 1982, p. 315-318. __1982b, Secondary maximum contaminant levels (section 143.3 of part 143, National secondary drinking-water regulations): U.S. Code of Federal Regulations, Title 40, Parts 100-149, revised as of July 1, 1982, p. 374. Walker, P. N., 1970, Water in Maryland A review of the Free State's liquid assets: Maryland Geological Survey, 52 p. Prepared by Laurence J. McGreevy and Judith C. Wheeler For further information contact Chief, Maryland Office, Mid-Atlantic District, U.S. Geological Survey, 8600 La Salle Road, Towson, MD 21204 U.S. Geological Survey Water-Supply Paper 2275 MASSACHUSETTS Ground-Water Resources National Water Summary Massachusetts 249 Table 1. Ground-water facts for Massachusetts [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983, and Richard Thibedeau, Massachusetts Division of Water Resources, written commun., 1984] Population served by ground water, 1980 One-third of the 5.7 million people in Massachusetts obtain their water supply from wells. Public-supply wells provide water to 1.5 million people, and private rural wells provide water to an additional 400,000 people (table 1). Although all the State's major urban areas use surface-water supplies, ground water is the primary source for 165 public supplies and a secondary source for an additional 33 public supplies. In 1980, an average 320 million gallons per day Number (thousands) - ----------------- 1 900 (Mgal/d) of fresh ground water was withdrawn for public, Percentage of total population --------------' 33 rural, industrial, and irrigation supplies. Of this, 59 percent From public water-supply systems: was for public supply, 29 percent was for industrial self-sup- Number (thousands) - --------------- 1,500 ply, and 10 percent was for rural domestic supply (table 1). Percentage of total population - ------------ 26 Contamination and drought have affected the ground- ^S±*2£SjT?*":. ............. 400 water resource in the past. Degradation of ground-water Percentage of total population- ------------- 7 quality by wastes and chemicals has caused water shortages. c_. * ,,., *,,,, ,.,.,, -mon D » irv-70 j inoi ic ui- i 11 -*u Freshwater withdrawals, 1980 Between 1978 and 1981, 25 public-supply wells with a com- - bined capacity of 23 Mgal/d were taken out of service because Surface water and ground water, total (Mgal/d) ------ 2,500 of ground-water contamination. Drought, caused by deficient ^^^eo^f^- I I I I I I I I I I I I I I I 3?3 precipitation, exacerbated these water-supply shortages in Percentage of total excluding withdrawals for 1981, a year when 38 communities declared water emergen- thermoelectric power ---------------- 28 cies. Also, road salt has contaminated local ground water, roto^ nf ,.oo i i i* « i i wwiGoory OT use causing several public and private-supply wells to be taken out of service. In response to these and other ground-water Public-supply withdrawals: ,, j ^ * . L. Ground water (Mgal/d)- --------------- 190 problems, a ground-water-assessment program has been Percentage of total ground water - ----------- 59 initiated by the Massachusetts Division of Water Resources Percentage of total public supply - ----------- 24 and the U.S. Geological Survey. Ground-water-quality pro- Per capita (gal/d) ------------------ 127 tection measures encouraged by State and Federal programs Rural-supply withdrawals: also are being implemented at the local government level. Domestic: Ground water (Mgal/d)- -------------- 32 ^r- ,-,-.., _._-.--.., /-N Percentage of total ground water - ---------- 10 GENERAL SETTING Percentage of total rural domestic ---------- 100 Massachusetts is included in two physiographic prov- .Per caPita (gal/d) ----------------- 80 inces the Coastal Plain and the New England Upland SSnd water (Mgal/d)- -------------- 0.7 (Fenneman, 1938). The Coastal Plain province includes Cape Percentage of total ground water - ---------- 0.2 Cod, Martha's Vineyard, and Nantucket (fig. 1); the province Percentage of total livestock - ------------ 58 is characterized by plains and low hills underlain by a contin- Industrial self-supplied withdrawals: uous blanket of unconsolidated sediments that cover bedrock Ground water (Mgal/d)- --------------- 93 ,o depths of 80 to 1,500 fee, (ft). The upper ,00 f, or more of £S3!S£dSriS£W^i: ------- 29 these sandy sediments form the most productive aquifers in Including withdrawals for thermoelectric power ----- 6 Massachusetts. Excluding withdrawals for thermoelectric power - - - - 30 Except for the Connecticut Valley Lowland subdivision, Irrigation withdrawals: the New England Upland province is underlain by crystalline Ground water (Mgal/d)- ---------------- 5 metamorphic and igneous rocks that are covered by a discon- Percentage of total ground water- ------------ 2 ., r f-,i j x *-r j j -rv T u- re Percentage of total irrigation ------------- 28 tinuous mantle of till and stratified drift. Topographic relief - - generally increases from the Seaboard Lowland in the east to the Berkshire Hills in the west. Stratified drift, which partly developed on sand and gravel is estimated to be about 21 in. fills the valleys of the New England Upland, forms small, and through soils developed on glacial till, about 6 in. Most isolated, productive aquifers that are scattered throughout the ground water is pumped from wells less than 300 ft deep, province. The Connecticut Valley Lowland is underlain by a Unlike aquifers in most other parts of the country, aquifers in sequence of red sandstone, shale, conglomerate, and a basaltic New England, in general, are relatively thin and many have lava flow, all dipping gently to the east where they are limited areal extent, with the result that aquifers tend to have terminated by normal faults against the older crystalline small storage capacity and are very susceptible to depletion rocks. Triassic and Jurassic rocks in this lowland are overlain during drought, by lacustrine sediments formed in postglacial Lake Hitchcock. Ground-water recharge in Massachusetts is derived from PRINCIPAL AQUIFERS precipitation which is rather uniformly distributed over the The principal aquifers in Massachusetts can be grouped State at an average annual rate of about 44 inches (in.). according to general rock type into stratified glacial drift, Recharge rates are dependent on slope, soil permeability, and sedimentary bedrock, carbonate rock, and crystalline bed- type of vegetation. Average annual recharge through soils rock. A brief description of each aquifer is given below and in 250 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Massachusetts [gal/min = gallons per minute; ft = feet; in. = inch. Sources: Reports of the U.S. Geological Survey and Massachusetts] Well characteristics Aquifer name and description Depth (ft) Yield (gal/min) Remarks Common range May exceed Common range May exceed Stratified-drift aquifer: Sand and gravel with silt, glacial outwash, ice-contact, and delta deposits; some beach and dune deposits included. Moraines also contain till. Generally unconfined, locally confined. Sedimentary bedrock aquifer: Red sandstone, shale, arkosic conglomerate, and basaltic lava flow. Generally, unconfined, confined at depth. Carbonate rock aquifer: Limestone, dolomite, and marble. Confined. Crystalline bedrock aquifer: Metamorphic and igneous rock predominantly gneiss and schist. Confined. 60-120 200 100-1,000 2,000 100-250 100-300 100-400 500 1,000 1,000 10-100 1-50 1 -20 500 Used extensively for public supply; also used for industry, fish hatcheries, agriculture, and rural supplies. Locally, large iron or manganese concentrations a problem. Some saline water intrusion in coastal areas. Low pH of water may corrode pipes and appliances. Used for rural supplies and some industry. Deep wells produce hard water. 1,000 Used for rural supplies and some industry Water hard. 300 Used for rural supplies. Locally, large iron concentrations a problem. Recently drilled wells generally deeper than older wells. LowpHof water may corrode pipes and appliances. 1 Well depths and yields reported for stratified drift are for public-supply wells. Rural domestic wells yield 5-80 gal/min from 1!4- to 2 !/z -inch-diameter well screens, 3 to 5 ft in length. table 2, from youngest to oldest. The distribution of aquifers is shown in figure 1. STRATIFIED-DRIFT AQUIFER Stratified glacial drift provides water for virtually all public supplies that use ground water. The stratified-drift aquifer, which consists of layered sand and gravel with some silt, was deposited over bedrock by glacial meltwaters as the last Wisconsin continental glacier retreated from New Eng- land. In most of Massachusetts, these deposits form small but very permeable valley-fill aquifers (fig. 1). Although these valley aquifers tend to have small volume and storage, they are very productive because of induced infiltration from traversing streams. However, as a result of infiltration induced by ground-water withdrawals, stream- flows have been depleted and some small streams temporarily have ceased flowing. Public-supply wells in the stratified-drift aquifers generally are 24 in. in diameter, less than 100 ft deep, screened and gravel packed in the lower 20 percent of the aquifer, and yield several hundred gallons per minute. The water table commonly is less than 20 ft below land surface, but artesian conditions are present in a few locations. In the southeastern corner of Massachusetts, the strati- fied-drift aquifer forms a continuous layer over bedrock rather than isolated valley deposits (fig. 1). Southern Plymouth County, Cape Cod, and the islands of Martha's Vineyard and Nantucket are mantled with 80 to several hundred feet of glacial moraine and outwash deposits of sand, gravel, and silt, with minor amounts of clay and some boul- ders (Guswa and LeBlanc, 1981; Delaney, 1980; Walker, 1980) (fig. 1). The upper 100 ft of the saturated parts of these deposits have been developed for public supplies. In areas not served by public supplies, water is obtained from l!4- to 4-in.-diameter wells that are screened about 15 ft below the water table. The sediments underlying the northwestern part of Martha's Vineyard consist of Tertiary clay. In this part of Martha's Vineyard, sufficient quantities of ground water for domestic supply cannot be obtained at most locations. How- ever, some widely scattered small sand lenses in the clay have been developed for rural domestic supplies. Water quality of the stratified-drift aquifer generally is suitable for human consumption and most other uses (Frimpt- er and Gay, 1979). The water generally is acidic (pH 6.1), soft [20 milligrams per liter (mg/L) as calcium carbonate], and has small concentrations of dissolved solids (70 mg/L). Iron (as much as 8.8 mg/L) and manganese (as much as 0.9 mg/L) have been measured in ground water on Cape Cod. The greatest threat to water quality in these areally extensive water-table aquifers is from incompatible land uses. Sewage disposal through septic systems and municipal systems, land- fills, dumps, road salt, and agricultural chemicals and pesti- cides are the most commonly recognized sources of ground- water-quality problems (Massachusetts Special Legislative Commission on Water Supply, 1981). In addition, two pub- lic-supply well fields and several private supplies have been affected by saltwater intrusion. SEDIMENTARY BEDROCK AQUIFER The Triassic and Jurassic sedimentary bedrock aquifer in western Massachusetts consists principally of consolidated red sandstone, conglomerate and shale (fig. 1). Well yields de- pend on interception of open fractures, but some intergranu- lar permeability, which is present in many of the sandstone units, sustains larger yields than would otherwise be expected. Well yields generally range from 10 to 100 gallons per minute (gal/min) but may exceed 500 gal/min (Walker and Caswell, 1977). Water generally is unconfined in the upper saturated 100 ft of the aquifer, but is confined at greater depths. Water from deep parts of the aquifer commonly is hard (greater than 300 mg/L) and may have large concentrations of sulfate (greater than 250 mg/L) and dissolved solids (greater than 600 mg/L) (see Wandle and Caswell, 1977). National Water Summary Massachusetts 251 73 0 10 20 30 40 50 MILES EXPLANATION Stratified-drift aquifers Till aquifer--Forms a fairly continuous cover over bedrock units Sedimentary-bedrock aquifer Crystalline-bedrock aquifer Carbonate-rock aquifer Not a principal aquifer MAN I!" KU WATER TABLE EIMGLAND 'UPLAND SECTION CONNECTICUT VALLEY LOWLAND B FRESHWATER ZONE Figure 1. Principal aquifers in Massachusetts. A, Geographic distribution. B, Physiographic diagram and divisions. C, Valley-fill stratified-drift aquifer. D, Continuous blanket stratified-drift aquifer. (See table 2 for more detailed description of aquifers. Sources: A, Delaney and Maevsky, 1980; Norvitch and others, 1968; Walker and Caswell, 1977; Hansen and others, 1973. B, Fenneman, 1938; Raisz, 1954. C, Frimpter, 1981. D, Compiled by M. H. Frimpter from U.S. Geological Survey files.) 252 National Water Summary Ground-Water Resources CARBONATE ROCK AQUIFER The carbonate rock aquifer is present in Berkshire Coun- ty and consists of limestone, dolomite, and marble formations interbedded with schist and quartzite (Norvitch and others, 1968) (fig. 1). Locally, fractures in these rocks have been enlarged by solution, which has considerably increased aquifer permeability. As a result, well yields that exceed 1,000 gal/ min have been reported (Norvitch and Lamb, 1966). Wells completed in this aquifer provide industrial and rural domestic supplies but no public supplies. The aquifer commonly is confined. Water from the aquifer is hard (100-350 mg/L as calcium carbonate). CRYSTALLINE BEDROCK AQUIFER Rural areas rely mostly on the crystalline igneous and metamorphic bedrock aquifer for water supply. Ground water in sufficient quantities for individual home supplies can be obtained almost everywhere. Water is present in secondary openings (fractures, joints, and fault or shear zones) in these otherwise-impermeable rocks (Massachusetts Division of Wa- ter Resources, 1976). The crystalline bedrock aquifer is not used on Cape Cod, Martha's Vineyard, and Nantucket be- cause it occurs at great depth, contains saline water, or is overlain by readily accessible water in stratified-drift aquifers. Well yields of more than 300 gal/min have been obtained from the crystalline bedrock aquifer, but such yields are very uncommon. These large-yield wells are located in very frac- tured zones and near saturated stratified drift, which serves as a recharge source to the bedrock fractures. In a few areas, the yields of bedrock wells are small and may be insufficient for domestic supply. Wells in the bedrock are considered to be artesian because water in the wells almost always rises above the level at which it is found. Some wells in this aquifer yield water with objectionable quantities of iron (greater than 0.3 mg/L and as much as 20 mg/L). Ground water at some locations has been contaminated with road salt, petroleum products, solvents, pesticides, or sewage. OTHER AQUIFERS A thin layer of unconsolidated glacial till overlies bedrock throughout Massachusetts. Early rural homesteads obtained water from this till almost exclusively by means of large- diameter (36-in.) shallow (commonly less than 30 ft deep) dug wells or from springs. Till generally is not considered to be a source for water supplies today because wells in till have small yields and are susceptible to drought and pollution. Also, advanced well-drilling techniques have made other aquifers more accessible. However, on the sparsely populated Eli- zabeth Islands, till is the only aquifer available and it yields small quantities of water to large-diameter wells. GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS In 1980, 23 pumping centers (towns or cities) produced more than 2 Mgal/d (fig. 2), 43 pumping centers produced 1 to 2 Mgal/d, and another 102 centers produced from 100,000 gallons per day to 1 Mgal/d (Richard Thibedeau, Massa- chusetts Division of Water Resources, written commun., 1984). Withdrawals are continuing to increase in response to increased demands, most notably on Cape Cod where the population increased by more than 50 percent during the 1970's. Long-term water-level declines have not been observed in any aquifer (fig. 2). Although the quantity of water stored in the stratified-drift aquifers is small, these aquifers are almost invariably adjacent to streams from which infiltration may be induced to sustain withdrawal by wells. Even though water levels have not shown a declining trend in response to with- drawals, seasonal water-level changes may be pronounced. Generally, very little recharge from precipitation occurs dur- ing the 180-day summer growing season. Ground-water with- drawals during this period are largely from aquifer storage or induced infiltration from streams or both. As would be expected, water-level fluctuations in a well tapping an aquifer from which freshwater is pumped for public supply and a local fish hatchery (location 24, figure 2) are greater than in a nearby unstressed aquifer (location 25, fig. 2). On Cape Cod, long-term water level declines have not occurred near a pump- ing center (location 21, fig. 2) or near an area where pumping has not occurred (location 26, fig. 2). GROUND-WATER MANAGEMENT All State agencies with ground-water management and planning responsibilities are managed by the Massachusetts Executive Office of Environmental Affairs. These responsi- bilities are carried out by the Departments of Environmental Management and of Environmental Quality Engineering (Massachusetts Department of Environmental Quality Engi- neering, 1984). The Massachusetts Water Resources Commission deve- lops and coordinates water-resources planning and manage- ment functions of the departments of the Massachusetts Executive Office of Environmental Affairs. In recognition of the interdependency of surface and ground water, the Com- mission has recommended a policy of preventing undesirable streamflow depletion through allocation of ground-water withdrawals for public supply. The Commission also esta- blishes criteria and priorities for all water-related cooperative programs with the Federal Government and with other agen- cies of the State. The Massachusetts Department of Environmental Man- agement (MDEM) has two divisions responsible for water activities the Division of Water Resources and the Bureau of Solid Waste Disposal. The Division of Water Resources collects and disseminates water-resources information and develops State water-resources plans (Water Resources Plan- ning Regulations 313 CMR 2.00). This division administers water-resources data-collection and ground-water-assessment programs with the U.S. Geological Survey and with other Federal agencies. It also licenses well drillers and maintains records of well-completion reports. The Bureau of Solid Waste Disposal works to protect ground-water quality by planning for solid- and hazardous- waste disposal through regional facilities and by the dissemi- nation of technical information. The Massachusetts Department of Environmental Qual- ity Engineering (MDEQE) has primary responsibility for ground-water quality through its Division of Water Supply, Division of Environmental Analysis, and Division of Hazard- ous Waste. The Division of Water Supply ensures drinking- water quality through its public-supply well-permit program. This division also collects and disseminates ground-water quality information and administers programs providing funds for water treatment and aquifer protection. The Division of Environmental Analysis is the MDEQE's analytical laboratory. It regularly collects and analyzes sam- ples of raw and treated public water supplies used for drink- ing-water purposes. It is also responsible for analyzing ground-water samples suspected of contamination. The Division of Water Pollution Control of MDEQE is responsible for improving water quality and preventing ground-water pollution. It regulates discharges of polluting matter originating from point or major nonpoint sources into National Water Summary-*Massachusetts 253 1 1e § IB o 2D 3 22 I 2f * 26 34 - 21 Stratified drift aquifer Unconfined 1 965 |J 985 24 Stratified drift aquifer Unconfined EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) e 1.0-2 © 2.1 -T 4 £ 4.1-6 Location number 3 6*°Hydrograph only 1975 1 985 26 Stratified drift aquifer Unconfined J____I____I____I____I 1955 1965 197S i 981 ~ 25 Stratified drift aquifer Unconfined s? 955 1965 t975 WITHDRAWAL SITES [Aquifers are all stratified drift. Withdrawals are principally for public supply.] No. on map 1 2 3 4 5 6 7 8 9 10 11 12 Geographic area Cheimsford Wiimington Woburn Wellesley Worcester Shrewsbury Natick Needham Dedham Hingham Easthampton Waipole No. on map 13 14 15 16 17 18 19 20 21 22 23 Geographic area Westfieid Marshfield Southwick Franklin Foxborough Mansfield Attleboro Piymouth Barnstable Yarmouth Dennis Figure 2. Areal distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Massachusetts. (Sources; Solley and others, 1983; Richard Thibedeau, Massachusetts Division of Water Resources, written commun., 1984.) 254 National Water Summary Ground-Water Resources ground water by permit. It also administers MDEQE's water-resources inventory and water-quality research pro- grams which it maintains in cooperation with universities and the U.S. Geological Survey (Isaac and others, 1983). The Division of Hazardous Waste of MDEQE regulates activities with a large potential for ground-water contamina- tion, responds to oil spills and other hazardous-waste acci- dents on an emergency basis, investigates illegal disposal activities, and supervises the cleanup of hazardous-waste sites. Its activities include the approval of ground-water monitoring programs, hydrogeologic studies, and evaluation of proposals for cleaning up contaminated ground-water. SELECTED REFERENCES In addition to reports listed below, hydrologic and geologic information was derived from the series of Hydrologic Atlases, Water Resources Basic-Data Reports, and Water Resources Investigations prepared cooperatively by the U.S Geological Survey and the Massa- chusetts Divisions of Water Resources and Water Pollution Control, and published by the U.S. Geological Survey. Delaney, D. F., 1980, Ground-water hydrology of Martha's Vineyard, Massachusetts: U.S. Geological Survey Hydrologic Investiga- tions Atlas HA-618. Delaney, D. F., and Maevsky, Anthony, 1980, Distribution of aqui- fers, liquid-waste impoundments, and municipal water-supply sources: U.S. Geological Survey Water-Resources Investigations 80-431, [map]. Fenneman, N. M., 1938, Physiography of Eastern United States: New York, McGraw-Hill Book Co., 714 p. Frimpter, M. H., 1981, Grovnd water for management: Cornell University conference, "Groundwater Use Management in the Northeastern States," June 2-4,1981, Proceedings, p. 95-103. Frimpter, M. H., and Gay, F. B., 1979, Chemical quality of ground water on Cape Cod, Massachusetts: U.S. Geological Survey Water-Resources Investigations 79-65, 11 p. Guswa, J. H., and LeBlanc, D. R., 1981, Digital models of ground- water flow in the Cape Cod aquifer system, Massachusetts: U.S. Geological Survey Water-Resources Investigations Open-File Report 80-67, 128 p. Hansen, B. P., Toler, L. G., and Gay, F. B., 1973, Hydrology and water resources of the Hoosic River basin, Massachusetts: U.S. Geological Survey Hydrologic Investigations Atlas HA-481. Isaac, R. A., Kimball, W. A., and Screpetis, A. J., 1979, Massa- chusetts Division of Water Pollution Control Research and Demonstration Program, 1979: Westborough, Mass., 69 p. Massachusetts Department of Environmental Quality Engineering, 1984, Groundwater program summary: Boston, 66 p. Massachusetts Division of Water Resources, 1976, Groundwater and groundwater law in Massachusetts: Boston, Massachusetts Wa- ter Resources Commission, 92 p. Massachusetts Special Legislative Commission on Water Supply, 1981, Water Quality issues in Massachusetts chemical contami- nation, Second Working paper of the Special Legislative Com- mission on Water Supply: Boston, 88 p. Massachusetts Water Resources Commission, 1983, Massachusetts water supply, safe yield, type of supply, proposed sources: Boston, 47 p. Norvitch, R. F., Farrell, D. F., Pauszek, F. H., and Petersen, R. G., 1968, Hydrology and water resources of the Housatonic River basin, Massachusetts: U.S. Geological Survey Hydrologic Investigations Atlas HA-281. Norvitch R. F., and Lamb, M. E. S., 1966, Housatonic River basin: U.S. Geological Survey, Massachusetts Basic-Data Report No. 9,40 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., Mann, W. B., IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Walker, E. H., 1980, Water resources of Nantucket Island, Massa- chusetts: U.S. Geological Survey Hydrologic Investigations AtlasHA-615. Walker, E. H., and Caswell, W. W., 1977, Map showing availability of ground water in the Connecticut River lowlands, Massa- chusetts: U.S. Geological Survey Hydrologic Investigations At- las HA-563. Wandle, S. W., Jr., and Caswell, W. W., 1977, Streamflow and water quality in the Connecticut River lowlands, Massachusetts: U.S. Geological Survey Hydrologic Investigations Atlas HA-562. Prepared by Michael H. Frimpter For further information contact District Chief, U.S. Geological Survey, 150 Causeway Street, Suite 1309, Boston, MA 02114 U.S. Geological Survey Water-Supply Paper 2275 MICHIGAN Ground-Water Resources National Water Summary Michigan 255 Ground water is the source of 17 percent of public-water supplies and nearly 100 percent of the domestic-water supplies in Michigan (Bedell, 1982). Ground water supplies 43 percent of the State's population; however, ground water accounts for only 4 percent of the total water used in the State because most supplies for large urban areas are from surface water, particu- larly the Great Lakes (Solley and others, 1983; Weist, 1978). Distant from the Great Lakes, water supplies generally are obtained from ground water. Ground-water withdrawal for irrigation is about 37 percent of the total water used for irrigation ( Bedell and VanTil, 1979; Solley and others, 1983). Ground-water withdrawals in 1980 for various uses, and related statistics, are given in table 1. Chemical characteristics of natural ground water in Mi- chigan are determined primarily by the geologic environment through which the water flows. Natural ground water general- ly is suitable for human consumption and most other uses. Water from glacial deposits, at places, contains large concen- trations of iron [2.5-5.0 milligrams per liter (mg/L)]; water from carbonate rocks is likely to be very hard (400-900 mg/L as calcium carbonate); and water from the Saginaw aquifer in the Saginaw Bay-Thumb area commonly is very mineralized (2,000-80,000 mg/L of dissolved solids). Throughout the State, salty water underlies freshwater at depths ranging from about 100 ft in the eastern part of the Lower Peninsula to about 900 ft in the northern part. Average dissolved-solids concentration of water from bedrock (535 mg/L) is about twice as great as the average concentration from glacial deposits (241 mg/L) (Cummings, 1980). Michigan has identified more than 1,000 sites where ground water has been contaminated to some degree and an even greater number of sites where pollution is suspected (Michigan Department of Natural Resources, 1985). A wide range of contaminants is involved. At many sites, chlorinated hydrocarbons and hydrocarbons that are contained in fuel substances are the contaminants. Nitrates from surface sources have contaminated domestic ground-water supplies in concentrations of as much as 30 mg/L at some locations in the Lower Peninsula (Cummings and others, 1984). GENERAL SETTING Michigan is divided into two principal physiographic provinces. The Lower Peninsula and the eastern part of the Upper Peninsula of Michigan are in the Central Lowland physiographic province. These areas are underlain by layered sedimentary bedrock of Paleozoic and Mesozoic age. The western part of the Upper Peninsula is a part of the Superior Upland physiographic province, which is underlain by igne- ous, metamorphic, and sedimentary rocks of Precambrian age. Glacial deposits cover most of the State. Glacial deposits consist of sand, gravel, silt, clay, and boulders. Sand and gravel, such as in outwash and glaciofluvi- al deposits, are productive aquifers; mixtures of clay, silt, sand, gravel, and boulders, which form some till deposits, Table 1. Ground-water facts for Michigan [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] Population served by ground water, 1980 Number (thousands) - ----------------- 3,978 Percentage of total population ------------- 43 From public water-supply systems: Number (thousands) ---------------- 1,310 Percentage of total population - ----------- 14 From rural self-supplied systems: Number (thousands) ---------------- 2,668 Percentage of total population - ----------- 29 Freshwater withdrawals, 1980 Surface water and ground water, total (Mgal/d) ------ 15,000 Ground water only (Mgal/d) -------------- 530 Percentage of total- ---------------- 4 Percentage of total excluding withdrawals for thermoelectric power --------------- 18 Category of use Public-supply withdrawals: Ground water (Mgal/d)- --------------- 220 Percentage of total ground water - ----------- 41 Percentage of total public supply- ----------- 17 Per capita (gal/d) ------------------ 168 Rural-supply withdrawals: Domestic: Ground water (Mgal/d)- -------------- 160 Percentage of total ground water ----------- 30 Percentage of total rural domestic ---------- 100 Per capita (gal/d) ----------------- 60 Livestock: Ground water (Mgal/d)- -------------- 17 Percentage of total ground water ----------- 3 Percentage of total livestock - ------------ 77 Industrial self-supplied withdrawals: Ground water (Mgal/d)- --------------- 62 Percentage of total ground water- ----------- 12 Percentage of total industrial self-supplied: Including withdrawals for thermoelectric power - - - - 1 Excluding withdrawals for thermoelectric power - - - - 3 Irrigation withdrawals: Ground water (Mgal/d)- --------------- 77 Percentage of total ground water - ----------- 14 Percentage of total irrigation ------------- 37 generally are poor aquifers. Lacustrine deposits that are predominantly sand are productive aquifers; those that are predominantly clay yield little or no water. In the northern part of the Lower Peninsula, glacial deposits in some areas are more than 800 feet (ft) thick; in most other areas in the State, the deposits are less than 200 ft thick. In the Lower Peninsula and eastern Upper Peninsula, bedrock, which underlies glacial deposits and crops out at a few places, consists principally of Paleozoic shale, limestone, and sandstone. These rocks have been deformed into a structural feature known as the Michigan basin (Newcombe, 1933). Sandstone and limestone are productive aquifers and, where near enough to land surface to be recharged by precipi- 256 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Michigan [Ft = feet; gal/min = gallons per minute. Sources: Reports of the U. S. Geological Survey and Michigan Department of Natural Resources, Geological Survey Division] Well characteristics Aquifer name and description Depth (ft) Common May range exceed Yield (gal/min) Common May range exceed Remarks Glacial aquifers: Outwash and glaciofluvial deposits: 25-200 400 1-1,000 2,000 Sand and gravel, contains silt and clay in places. Mostly unconfined. Lacustrine sand: Sand, some gravel, 25-100 200 80-500 500 and interbedded silt and clay. Mostly unconfined. Till: Intermixed clay, silt, sand, 25-200 400 5-200 gravel and boulders; sand and gravel lenses abundant in some areas. Confined and unconfined. Bedrock aquifers: Saginaw Formation: Sandstone, 25-300 500 100-300 1,000 siltstone, some shale, limestone, and coal. Mostly confined. Marshall Formation: Sandstone 25-200 400 100-500 1,500 and siltstone. Mostly confined or semiconfined, unconfined at places. Silurian-Devonian rocks: 25-150 200 10-300 500 Limestone and dolomite; some shale and sandstone. Mostly confined. Cambrian-Ordovician rocks: 25-150 200 10-100 500 Sandstone, limestone, and dolomite. Mostly confined. Precambrian sandstone: Sandstone 25-400 500 5-50 100 interbedded with siltstone. Mostly confined. Water generally hard; large iron concentrations common; deep wells may produce salty water in places. Used for domestic supplies in Saginaw Bay and Detroit areas; is salty in places at depth. 200 Primary source of domestic supply in western Upper Peninsula. One of Michigan's most important bedrock aquifers; water generally hard; salty in places at depth. Another of Michigan's important bedrock aquifers; salty in places and at depth. Important aquifer in parts of eastern Upper Peninsula; water commonly hard. Important aquifer in eastern Upper Peninsula; water commonly very hard; salty in places and at depth. Important aquifer in western Upper Peninsula; salty in places. tation, they produce freshwater. However, where deeply buried, these sedimentary rocks yield brackish or salty water. In some places, this brine is pumped for commercial use. In the western Upper Peninsula, bedrock consists of Precambrian igneous, metamorphic, and sedimentary rocks. Igneous and metamorphic rocks generally are poor aquifers. Most ground-water production in this area is from glacial deposits and Precambrian sandstone. However, two public- water supplies are from old mine shafts in the igneous and metamorphic rocks. Annual recharge to unconfined aquifers in Michigan ranges from 3 to 18 inches (in.) and is derived from precipita- tion which averages 31 in. annually. Some recharge moves to deep aquifers; however, most flows from shallow aquifers to nearby streams and accounts for about 55 percent of the State's streamflow. PRINCIPAL AQUIFERS The principal aquifers in Michigan consist primarily of glacial deposits and sedimentary bedrock. Characteristics of the aquifers are described below and in table 2, from youngest to oldest; their areal distribution is shown in figure 1. GLACIAL AQUIFERS Lacustrine Sand Aquifers Lacustrine sand is the major aquifer along Lake Huron northwest of Saginaw Bay and in parts of southeastern Michi- gan. This material was deposited when lake levels were higher in the Great Lakes basins. Some areas near Saginaw Bay and in southeastern Michigan are underlain by lacustrine clay, which yields little or no water. Dissolved-solids concentra- tions generally range from 100 to 500 mg/L. Outwash and Glaciofluvial Aquifers In the northern and western parts of the Lower Penin- sula, outwash and glaciofluvial deposits generally are thick and coarse grained; in most of this area, ground-water sup- plies are abundant. In the western Upper Peninsula, however, outwash and glaciofluvial deposits tend to be thin and isolat- ed; many wells in this area fail to yield sufficient supplies during periods of less-than-average precipitation. Dissolved- solids concentrations in all areas generally range from 100 to 500 mg/L. National Water Summary Michigan 257 EXPLANATION GLACIAL AQUIFERS k": -'." ;. ] Lacustrine sand, outwash and >;'.''' ' ' '] glaciofluvial deposits, and till BEDROCK AQUIFERS Saginaw Formation I I Marshall Formation Silurian-Devonian rocks Cambrian-Ordovician rocks Precambrian sandstone [ | NOT A PRINCIPAL AQUIFER ^ A' Trace of cross section 50 100 MILES -1 /LakeJuperi^ Lake Michigan Sea level A' Lake Erie r- Igneous and Metamorphic rock -4000' - -8000' - -12,000' Figure 1. Principal aquifers in Michigan. A, Geographic distribution. B, Physiographic diagram and divisions. C, Generalized cross section (A-A'). (See table 2 for more detailed description of aquifers. Sources: A, Farrand, 1982. B, Martin, 1936; Raisz, 1954. C, Compi led by N. G. Grannemann from U.S. Geological Survey files.) 258 National Water Summary Ground-Water Resources Till Aquifers In parts of the western Upper Peninsula, till generally contains lenses and beds of sand and gravel that provide sufficient water for domestic supplies. Elsewhere in the State, till consists of a poorly sorted mixture of rock materials of little permeability. Dissolved-solids concentrations generally range from 100 to 500 mg/L. BEDROCK AQUIFERS Saginaw Formation The Saginaw Formation is an important aquifer in much of the central and eastern parts of the Lower Peninsula. The formation, which is of Pennsylvanian age, is primarily sand- stone and siltstone in the Lansing area; it is siltstone and fined-grained sandstone interbedded with shale, limestone, coal, and gypsum in the Saginaw Bay area. Near Lansing, transmissivity of the formation ranges from 130 to 3,300 square feet per day (ft2/d) depending on differences in degree of fracturing, number of bedding-plane fractures, thickness of the sandstone, and ratio of sand to shale. Sandstone at shallow depths is more permeable than deeply buried sand- stone because fractures tend to decrease with depth (Vanlier and others, 1973). The formation is confined in most places. Recharge to the formation is primarily through the overlying glacial and lacustrine deposits. Water of the Saginaw Forma- tion generally is hard; the average dissolved-solids concentra- tion of the water is 1,600 mg/L (Cummings, 1980). Dissolved solids are less (300-800 mg/L) in areas where the aquifer is an important source for municipal supplies such as the Lansing area. ally are confined. Recharge to the formation is primarily through the overlying lacustrine deposits. Water of Silurian- Devonian rocks generally has a dissolved-solids concentration of less than 500 mg/L. Cambrian-Ordovician Aquifers Cambrian-Ordovician rocks are important aquifers in the east-central part of the Upper Peninsula. The rocks are principally fine- to coarse-grained sandstone in the lower part and limestone and dolomite in the upper part. Transmissivity values for these rocks depend primarily on lithology and thickness. Generally, the aquifers are confined. Recharge to the aquifers is primarily through the overlying glacial deposits. Dissolved-solids concentrations of water from Cambrian- Ordovician rocks range from about 150 to 2,000 mg/L. Precambrian Sandstone Aquifers Precambrian sandstones are aquifers only in the north- western Upper Peninsula where they are used by small com- munities and for domestic supplies. Because they are well- cemented and interbedded with siltstone and shale, Precam- brian sandstones yield water primarily from fractures (Van- lier, 1963). Transmissivity values generally are small. At most places, the aquifer is confined. Recharge to the formation is primarily through the overlying glacial deposits. Dissolved- solids concentrations of water from Precambrian sandstones are generally less than 1,000 mg/L. Marshall Formation The Marshall Formation is one of the most productive bedrock aquifers in the State. The formation, which is of Mississippian age, is composed of siltstone and fine- to medi- um-grained sandstone. Transmissivity values for the Marshall Formation range from 2,700 to 67,000 ftVd (Vanlier, 1966), depending primarily on differences in thickness, size, and number of fractures. Although the Marshall Formation un- derlies much of the Lower Peninsula, it is used as an aquifer only in the southern part of the Lower Peninsula and in the Thumb area; elsewhere in the Lower Peninsula, water in the Marshall Formation is either too salty for use or other aqui- fers, closer to the land surface, are used. The formation is unconfined in some locations but generally is confined or semiconfined. Recharge to the formation is primarily through the overlying glacial and lacustrine deposits. Water of the Marshall Formation generally has a dissolved-solids concen- tration of less than 500 mg/L. Silurian-Devonian Aquifers Silurian-Devonian rocks, consisting principally of lime- stone and dolomite with some shale and sandstone, are aqui- fers in the northern and southeastern Lower Peninsula and in the southern part of the eastern Upper Peninsula (fig. 1). Transmissivities of these aquifers depend, to a large extent, on the number and interconnection of fractures and solution channels and on thickness. Silurian-Devonian aquifers gener- GROUND-WATER WITHDRAWALS AND WATER-LEVEL TRENDS Location of major ground-water withdrawals and trends of ground-water levels near three locations are shown in figure 2. All major pumping centers are in the southern part of the Lower Peninsula; some tap bedrock aquifers, and others tap glacial deposits. Ground water is the source of water for 380 public-water supplies. Of these, 70 communities with a total population of 500,000 obtain water from the Marshall and Saginaw Formations. The Lansing metropolitan area withdraws the largest amount of ground water in the State. In 1983, the city of Lansing pumped 8.1 billion gallons (gal) from about 125 wells that tap the Saginaw Formation and unconsolidated glacial deposits. Four other water-supply systems in the area pumped 4.9 billion gal from about 50 wells. Intensive development of ground water in the area has produced a 100-square mile cone of depression. Near the center of the cone, water levels have declined as much as 160 ft. Water levels generally decline in response to increases in pumping and recover as pumping is reduced. This effect, on a long-term basis, is shown by the hydrograph for Lansing (location 1). During the period of record shown in figure 2, the effects of discontinued pumpage from nearby production wells are shown by a rising water-level trend from 1969 to 1977 in the observation well. National Water Summary Michigan 259 I " 1 20 § 40 S 60 § 80 35 te 100 160 180 1 Saginaw Formation aquifer Confined 1935 1945 1955 1965 3 Marshall Formation aquifer Confined/ Unconfined EXPLANATION Ground-water withdrawals, 1980 (million gallons per day) O 3-5 9-10 * 16 132 Location number O Withdrawal site 1935 1945 1975 20 40 60 80 100 °° 140 16° 180 4 Saginaw and Marshall Formations aquifers Confined 1935 1945 1975 1985 WITHDRAWAL SITES [Withdrawals are principally for public supply] No. on map 1 2 3 4 5 6 7 8 Geographic area Lansing, East Lansing, Michigan State University. Waterford Township . . . . Ypsilanti, Ypsilanti Township. Aquifer Saginaw Formation, glacial deposits. Glacial deposits. Marshall Formation. Saginaw and Marshall Formations. Glacial deposits. Do. Do. Marshall Formation. Figure 2. Area! distribution of major ground-water withdrawals and graphs of annual greatest depth to water in selected wells in Michigan. (Sources: Withdrawal data from Bedell, 1982; water-level data from U.S. Geological Survey files.) 260 National Water Summary Ground-Water Resources GROUND-WATER MANAGEMENT Two State agencies, the Department of Public Health and the Department of Natural Resources, are involved in regulat- ing and managing Michigan's ground-water resources. The Department of Public Health, through the county health departments, issues permits for domestic and public- supply wells and requires well drillers to submit copies of drilling records to the county health departments. This department also monitors the quality of public-water supplies. The Department of Natural Resources assists ground- water users by maintaining files of drilling records and by performing hydrogeologic and ground-water-quality studies. The Department also maps and describes geologic formations and monitors mineral wells and subsurface injection of brine. SELECTED REFERENCES Bedell, D. J., 1982, Municipal water withdrawals in Michigan: Michigan Department of Natural Resources, Water Manage- ment Division, 43 p. Bedell, D. J., and VanTil, R. L., 1979, Irrigation in Michigan: Michigan Department of Natural Resources, Water Manage- ment Division, 37 p. Cummings, T. R., 1980, Chemical and physical characteristics of natural ground waters in Michigan A preliminary report: U.S. Geological Survey Open-File Report 80-593, 34 p. Cummings, T. R., Twenter, F. R., and Holtschlag, D. J., 1984, Hydrology and land use in Van Buren County, Michigan: U.S. Geological Survey Water-Resources Investigations Report 84-4112, 124 p. Farrand, W. D., 1982, Quaternary geology of Southern Michigan Quaternary geology of Northern Michigan: Ann Arbor, Univer- sity of Michigan Department of Geological Sciences, [maps]. Martin, H. M., compiler, 1936, The centennial geological maps of the Northern Peninsula of Michigan The centennial geological map of the Southern Peninsula of Michigan: Michigan Geologi- cal Survey Division Publication 39, Geological Series 33, [maps]. Michigan Department of Natural Resources, 1982, Assessment of ground-water contamination Inventory of sites: Ground-water Quality Division, Lansing, 242 p. __1985, Michigan sites of environmental contamination priority list: Groundwater Quality Division, Lansing, 185 p. Newcombe, R. B., 1933, Oil and gas fields of Michigan: Michigan Department of Natural Resources, Geological Survey Division, Publication 38, 293 p. Raisz, Erwin, 1954, Physiographic diagram, p. 59, in U.S. Geological Survey, 1970, National atlas of the United States: Washington, D.C., U.S. Geological Survey, 417 p. Solley, W. B., Chase, E. B., and Mann, W. B. IV, 1983, Estimated use of water in the United States in 1980: U.S. Geological Survey Circular 1001, 56 p. Vanlier, K. E., 1963, Reconnaissance of the ground-water resources of Alger County, Michigan: Michigan Department of Natural Resources, Water Investigation 1, 55 p. __1966, Ground-water resources of the Battle Creek area, Michi- gan: Michigan Department of Natural Resources, Geological Survey Division, Water Investigation 4, 52 p. Vanlier, K. E., Wood, W. W., and Brunett, J. D., 1973, Water-supply development and management alternatives for Clinton, Eaton, and Ingham Counties, Michigan: U.S. Geological Survey Wa- ter-Supply Paper 1969, 111 p. Weist, W. G., Jr., 1978, Summary appraisals of the nation's ground- water resources Great Lakes Region: U.S. Geological Survey Professional Paper 813-J, 36 p. Prepared by N. G. Grannemann, F. R. Twenter, G. C. Huffman, and T. R. Cummings For further information contact District Chief, U. S. Geological Survey, 6520 Mercantile Way, Suite 5, Lansing, MI 48910 U.S. Geological Survey Water-Supply Paper 2275 MINNESOTA Ground-Water Resources National Water Summary Minnesota 261 Table 1. Ground-water facts for Minnesota [Withdrawal data rounded to two significant figures and may not add to totals because of independent rounding. Mgal/d = million gallons per day; gal/d = gallons per day. Source: Solley, Chase, and Mann, 1983] Population served by ground water, 1980 Minnesota is a State renowned for its surface water. However, 94 percent of the public-supply water systems and 75 percent of all Minnesotans derive their domestic water supplies from ground water. In addition, about 88 percent of the water used for agricultural irrigation is supplied by ground water. Ground-water withdrawals for irrigation are compet- ing for available supplies with nearby domestic wells, particu- Number (thousands) - ----------------- 3,051 larly in parts of western Minnesota where buried-drift aquifers Percentage of total population -------------- 75 . , , _, ,. . . .. From public water-supply systems: are widely used. The quality of water in most aquifers Number (thousands) - --------------- 1,910 statewide is suitable for most uses. However, ground water is Percentage of total population - ------------ 47 unsuitable for some uses because of naturally occurring saline From rural self-supplied systems: water along the western border of Minnesota and along the Per?en?a^ - - ------ ' - - - U 28 north shore of Lake Superior and because of nitrate contami- Freshwater withdrawals, 1980 nation in the karst area of southeastern Minnesota. Ground- water withdrawal for various uses in !980 and other related statistics are given in table 1. Percentage of total- ----------------- 22 Percentage of total excluding withdrawals for thermoelectric power ---------------- 48 _____________Category of use_____________ GENERAL SETTING Public-supply withdrawals: OCINCHML OCI I UNO Ground water (Mgal/d)- --------------- 230 Differing geologic features and land forms of Minnesota Percentage of total ground water- ----------- 34 cause significant differences in ground-water conditions. Percentage of total public supply- ----------- 52 . . . , , fc . , ._ ,. Per capita (gal/d) ------------------ 120 Minnesota is situated on the southern margin of the Canadian Rural-supply withdrawals: Shield, which is a region of Precambrian crystalline and Domestic: metamorphic rocks. In Paleozoic times, nearly 2,000 feet (ft) Ground water (Mgal/d)- - ------------- 120 _ , . , , .. j . . 11 Percentage of total ground water - ---------- 18 oi clastic and carbonate sediment was deposited in a shallow Percentage of total rural domestic ---------- 100 depositional basin in southeastern Minnesota known as the Per capita (gal/d) ----------------- 105 Hollandale embayment. Minnesota's most productive aqui- Livestock: ,. . . f f , 4 ,. , , , Ground water (Mgal/d)- -------------- 58 fers consist of a sequence of sandstone, limestone, and dolo- Percentage of total ground water - ----------- 9 mite beds in the Hollandale embayment (Delin and Wood- Percentage of total livestock - ------------ 85 ward, 1984). During the Pleistocene Epoch, four continental Industrial self-supplied withdrawals: glaciations advanced and retreated across Minnesota, blanket- ^^^^nA^: I I I I I I I I I I I '?? ing the bedrock with drift as thick as 700 ft. Sand and gravel Percentage of total industrial self-supplied: deposits in the drift constitute important aquifers, particularly Including withdrawals for thermoelectric power ----- 5 in western Minnesota where the drift is thickest and where . . Excluding withdrawals for thermoelectric power - - - - 20 Irrigation withdrawals: bedrock aquifers have small yields. Ground water (Mgal/d)- ------ -------- 140 Precipitation, which ranges from about 19 inches (in.) in Percentage of total ground water- ----------- 21 the northwestern corner of the State to about 32 in. in the Percentage of total irrigation ------------- 88 southeastern corner, supplies water to four major drainage basins Hudson Bay, St. Lawrence, Mississippi, and Mis- souri. As much as 30 percent of the precipitation infiltrates and becomes part of an extensive ground-water system. PRINCIPAL AQUIFERS The 14 principal aquifers (Adolphson and others, 1981) in Minnesota can be grouped according to general rock type into crystalline (igneous and metamorphic) rocks, volcanic rocks, sedimentary rocks (sandstone, sandstone and carbonate, and carbonate), and unconsolidated glacial drift and alluvium. The aquifers are described below and in table 2; their areal distribution is shown in figure 1. UNCONSOLIDATED GLACIAL-DRIFT AQUIFERS Surficial-Drift Aquifers Surficial-drift aquifers are exposed at land surface and cover about one-third of the State. These aquifers consist of alluvial outwash, beach-ridge, valley-train, and ice-contact deposits (fig. 1). Extensive outwash deposits are a significant source of water for irrigation wells in central Minnesota. Generally, iron and manganese concentrations are greater than 1 milligram per liter (mg/L), and, locally, concentrations of nitrite plus nitrate as nitrogen exceed 30 mg/L. 262 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Minnesota [Gal/min = gallons per minute; ft = feet; mg/L = milligrams per liter. Sources: Reports of the U. S. Geological Survey] Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Remarks Common range May exceed Unconsolidated glacial-drift aquifers: Surficial-drift aquifers: Sand and (or) gravel deposits located at or near land surface. Generally unconfined. Buried-drift aquifers: Sand and (or) gravel deposits located within thick drift. Generally confined. Sedimentary bedrock aquifers: Cretaceous aquifer: Sandstone lenses near the base of a predominantly shale section. Generally confined. Upper Carbonate aquifer: Limestone, dolomite, and dolomitic limestone. Generally confined. St. Peter aquifer: Fine- to medium-grained sandstone. Generally confined. Prairie du Chien-Jordan aquifer: Mainly dolomite and sandstone. Generally confined; unconfined near Minnesota and Mississippi Rivers. Red River-Winnipeg aquifer: Mainly sandstone and limestone with shale stringers. Generally confined. Ironton-Galesville aquifer: Mainly sandstone with interbedded shale and dolomitic sandstone. Generally confined. Mount Simon-Hinckley aquifer: Sandstone siltstone, and shale. Generally confined. Crystalline bedrock aquifers: North Shore Volcanics aquifer: A series of basaltic lava flows and interbedded sedimentary rocks. Generally confined. Sioux Quartzite aquifer: Well-cemented quartzite. Commonly unconfined. Proterozoic Metasedimentary aquifer: Thin-bedded gray to black argillite. Generally confined. 30-240 100-800 2,000 Generally good quality water. Large concentrations of iron and manganese in some areas. Nitrate contamination present in some areas. 80-380 100-600 1,500 Commonly hard water. Large iron, sulfate, and chloride concentrations in some areas, particularly where underlain by Cretaceous and Red River-Winnipeg aquifers. 280-620 10-250 1,000 Commonly hard water. Large sulfate, chloride, and dissolved-solids concentrations in many areas. 120-480 200-500 1,000 Includes Cedar Valley, Maquoketa, Dubuque, and Galena Formations. Locally, in karst area, water from a few wells contains large concentrations of nitrate and iron. 110-614 100-250 1,000 Generally good quality water. Large iron, sulfate, and manganese concentrations in some areas, particularly where overlain by Cretaceous aquifer. 170-910 500-1,000 2,700 Generally good quality water. Large iron and sulfate concentrations in some areas, particularly where overlain by Cretaceous aquifer. Locally, water has large concentrations of nitrate, iron, and manganese. 260-480 100-250 500 Dissolved-solids concentrations range from 3,000 to 60,000 mg/L. Large iron, sodium, and chloride concentrations. 170-640 40-400 1,500 Generally good quality water. Large concentrations of iron, sulfate, and hardness in some areas, particularly where overlain by Cretaceous aquifer. 90 - 1,130 400-700 2,000 Generally good quality water. Large iron, sulfate, boron, and chloride concentrations in some areas, particularly where overlain by Cretaceous aquifer. 20-930 5-25 100 Yields water from interflow sediments and from joints and fractures in basalt. Saltwater present in some areas north of Lake Superior. 120-1,300 5-100 450 Commonly hard water. Large sulfate concentration, particularly where mixed with water from Cretaceous aquifer. 30-500 5-70 250 Small dissolved-solids concentration. Commonly used in conjunction with underlying Biwabik Iron Formation aquifer for public and industrial supplies. National Water Summary Minnesota 263 EXPLANATION Boundary where Quarternary deposits are less than 50 feet thick EXPLANATION SEDIMENTARY BEDROCK AQUIFERS Cretaceous I Upper Carbonate St. Peter and Prarie du Chien - Jordan ^^H Red River - Winnipeg Ironton - Galesville and Mount Simon - Hincklev CRYSTALLINE BEDROCK AQUIFERS North Shore Volcanics Sioux Quartzite I Proterozoic Metasedimentary Biwabic - Iron Formation Precambrian undifferentiated 50 I 100 MILES Figure 1. Principal aquifers in Minnesota. A, Geographic distribution of bedrock aquifers. B, Geographic distribution of surficial-drift aquifers and physiographic diagram. (See table 2 for more detailed description of the aquifers. Sources: A, Woodward, 1984. B, Compiled by D. G. Woodward from U.S. Geological Survey files; Raisz, 1954.) 264 National Water Summary Ground-Water Resources Table 2. Aquifer and well characteristics in Minnesota Continued Well characteristics Aquifer name and description Depth (ft) Common range Yield (gal/min) Common May range exceed Remarks Biwabik-Iron Formation aquifer: Ferruginous chert. Generally confined; unconfined locally. Precambrian undifferentiated aquifer: granite, greenstone, and slate. Generally confined. 170-600 30 - 450 250 - 750 1,000 Hard water and large iron concentration in some areas. Most productive source of ground water in Mesabi Iron Range. 5-25 100 Commonly hard water. Large sulfate chloride concentrations found in Buried-Drift Aquifers Buried-drift aquifers are present in nearly all areas of the State except in the northeast and southeast where the drift is thin or absent (fig. 1). Aquifers consist of discontinuous lenses of fine to coarse sand and gravel that are isolated from one another by till. Buried-drift aquifers are used extensively for supplying water to public-supply, irrigation, and farm wells in central and southwestern Minnesota. Locally, water in the aquifers can contain large concentrations of iron (4.6 mg/L), sulfate (1,200 mg/L), and chloride (1,000 mg/L). SEDIMENTARY BEDROCK AQUIFERS Cretaceous Aquifer The Cretaceous aquifer underlies drift in southwestern and western Minnesota. Water from the aquifer is used primarily for rural domestic and stock supplies. It contains locally large concentrations of dissolved solids (3,540 mg/L), chloride (1,500 mg/L), and sulfate (1,700 mg/L), particularly in areas southwest of the Minnesota River (Woodward and Anderson, 1985). ranges from 200 to 400 mg/L as calcium carbonate (Ruhl and others, 1984b). Prairie du Chien-Jordan Aquifer The Prairie du Chien-Jordan aquifer is present in the central and southern parts of the Hollandale embayment. Water supplies from the aquifer have been slightly to moder- ately developed in the southeast and well developed in the Minneapolis-St. Paul metropolitan area where it provides about 80 percent of the annual ground-water supply (Horn, 1983). Locally, water from the aquifer has large concentra- tions of nitrate (29 mg/L), iron (1.4 mg/L), and manganese (420 mg/L) (Ruhl and others, 1985b). Red River-Winnipeg Aquifer The Red River-Winnipeg aquifer underlies several hun- dred feet of till and lake sediments of Glacial Lake Agassiz in the northwest corner of the State. Water from the aquifer is very mineralized; dissolved-solids concentrations range from 3,000 to 60,000 mg/L. The water is a sodium chloride type (Ruhl and Adolphson, 1985). Upper Carbonate Aquifer The Upper Carbonate aquifer is present in the southern part of the Hollandale embayment and is the source of water for many public-supply, industrial, and rural domestic wells. …