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\ \ s | MS DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY oe) 77) Y0.8Y-E07 Prepared in cooperation with the WATER RESOURCES RESEARCH INSTITUTE OF THE COLLEGE OF THE VIRGIN ISLANDS GEOLOGICAL SURVEY, WRD OPEN-FILE DATA REPORT 84-807 Be RECONNAISSANCE OF GROUND-WATER QUALITY IN THE U.S. VIRGIN ISLANDS, JULY 1984 UNITED STATES GEOLOGICAL SURVEY WATER RESOURCES DIVISION OPEN-FILE DATA REPORT 84-807 _ SELES LEZ ZZ=Z=EZ-UF BEE a VU U Prepared in cooperation with the WATER RESOURCES RESEARCH INSTITUTE OF THE COLLEGE OF THE VIRGIN ISLANDS 1984 RECONNAISSANCE OF GROUND-WATER QUALITY IN THE U.S. VIRGIN ISLANDS, JULY 1984 By Rene Garcia and Michael Canoy INTRODUCTION The demand for ground water in the U. S. Virgin Islands, specially for domestic use has increased marked- ly in recent years. In 1982, ground water withdrawals for public and domestic use in the U.S. Virgin Islands were about 1.1 million gallons per day (Torres and Dacosta;, 1984). Recent investigations show that addi- tional withdrawals might be possible (F. G6dmez-Godmez, USGS personal commun., 1984). In spite of increasing demands for ground water, data on its quality is very scarce. The lack of data constitutes a major gap in the knowledge of the U.S. Virgin Islands' hydrologic environment. There are no active water-quality monitoring networks and the most recent reconnaissance was conducted nearly two decades ago (Cosner, 1972; Jordan, 1975; Jordan and Cosner, 1973; bi 5 L972) ‘ GEOLOGICAL re ison ) Bete Va, Loa In 1984, the U.S, Geological Survey, Water Resources F 95 Division, conducted a reconnaissance of the ground-water EB 2 1985 qu%lity at selected wells throughout the U.S. Virgin / fuer Islands Cities 1). The investigation was conducted in “cooperation with the Water Resources Research Institute of the College of the Virgin Islands. Wells representing the principal aquifers (fig. 2 and tables 1 to 5), were sampled for physical, chemical and bacteriological characteristics. Selected wells were also sampled to determine potential contamination with priority pollutants as designated by the U.S. Environmental Protection Agency (EPA). This report summarizes the data collected during the investigation (July 1984). The data will provide a base line for future investigations and an assessment of water use versus quality. We wish to thank the U.S. National Parks Service, Public Works Department in St. Croix and St. John, and the Director of Conservation and Cultural Affairs in St. Thomas for their assistance. % 67°00’ 6600' 65°00’ T : i u T ATLANTIC OCEAN 18°30’ ST. THOMAS PUERTO RICO Culebra ST. JOHN U.S. 18°00’ Wiegues VIRGIN ISLANDS CARIBBEAN SEA ST. CROIX ) 10 20 30 40 MILES 17°30’ : | i] i f Figure 1.--Geographic location of the U.S. Virgin Islands. Table 1.--Physical, chemical, and bacteriological characteristics from selected wells in the U.S. Virgin Islands, July 1984. WELL || LOCATION OPERATED] DWL T ve pH METHODS AND PROCEDURES al Kee (LAT/LONG) WEE oe BY (FT) (DEG C) — (UNITS) a oa es — eee one i Nineteen wells in the U.S. Virgin Islands (fig. 2 1 | 176245644758 Golden Grove no. 1 OPW 36.75 29.0 1725 7.4 574 K 8 1 0.255 Ce 750 0.040 i and tables 1 to 5), were sampled as follows: eight wells 2 174308646841 Adventure no. 16 DPW 40.74 33.0 1759 7.6 531 <1 ee 2190 710 2014 3. in St. Croix (map numbers 1 to 8), seven wells in St. 3 174258645222 Prosperity no. 1 DPw 34.82 28.5 9325 7.0 316 <4 K & C25 14 «0901 ue Thomas (map numbers 9 to 15), and four wells in St. John 4 174329644547 Barren Spot now 5 OPW 70.96 27.5 3175 7.6 597 <1 K 2 C16 1.0 2915 ° (map numbers 16 to 19). The wells were selected to 5 1742256464719 Fairplains no. 6 CPW 58.07 a 5759 7.0 489 <4 <4 016 » 687 - 071 ° represent the most important pumping centers. The samples were collected as close as possible to the well 6 174527644601 Concordia noe 1 DPW 235227 27.5 2975 70 458 < 4 40 e045 (er 10 2013 a? casing. Methods described by Classen (1982), were used 7 4746596464716 Rust-up-twist PO 32.13 27.0 2550 704 590 K 4 5800 030 2850 «052 an for the collection of the samples. 8 174526643713 Zell’s well PO 78.93 32.25 4675 7.2 446 38 23c0 2016 2940 2014 <a 9 182033645312 VeITeHeA. now 2 VIHA 73.84 29.0 1150 Ae 602 1 65 2008 ND -909 Net Temperature, specific conductance, pH and total 10 181913645307 Bavoni noe 2 PO 240357 28.5 2359 722 554 < 1 370 2011 &.0 2309 224 alkalinity of the samples were measured at each site immediately upon collection of the samples. The depth of 11 182036645813 CoVoI. now 2 CVI 46.83 29.0 1250 724 485 1 3% -007 5.8 2011 +24 the water level below land surface was also determined. 412 182141645746 Agriculture Station USCA 65.15 25-5 1909 7 es 448 1 23 »CO9 A ot 2054 Tiel) Samples for chemical analysis of trace elements, common 13 181945645257 Polycarib no. 3 PO 118.27 28.6 2425 Tue 580 1 K 488 -016 2.3 -003 3.3 ions and nutrients were collected, filtered, and 14 182130645745 Bryan”’s Well now 2 PO ND 25.5 1250 6.9 251 K 36 4 C06 2.8 065 «7 preserved in accordance with procedures described by 415 182142645427 Mohagony Run now? PO 81.70 28.0 2230 6.8 580 <4 4700 < 2007 < .010 <.001 2.0 Skougstad and others (1979), and Goerlitz and Brown (1972). Samples for the determination of priority 16 182112644519 NePeSe NOe 9 USNPS ND 27.0 1925 6.8 518 < 1 10 e005 «597 - 009? 1.2 pollutants were collected at five wells (map numbers 4, 17 18205 3644322 Carolina well DPW 5.82 2fe5 2009 6.8 287 6 109 ef08 vee a0V2 Tare ame Pe <2 and 19), and preserved in accordance with 18 182010644728 NaPeSe NOe 2 USNPS 2715 29.0 25¢C0 7.0 560 30 3900 a017 4.9 2012 2.0 methods established by Brown and others (1970). The 19 182043644546 Sussanaberg no. 5 DPW 62.389 25.5 1459 720 538 5 8 < 001 qials 2007 127 samples were shipped to the U.S. Geological Survey National Water-Quality Laboratory in Doraville, Georgia, E xX P L A N A T I Oo N for chemical analyses. Determinations of fecai coliform and fecal streptococci bacteria were completed from raw water samples using the membrane filter method (Greeson and others, 1977). Processing and incubation of the samples were begun in the field shortly after collection. RESULTS Results of the field and laboratory determinations DWL - Depth to water level below land surfaces in feet J - Temperatures in degrees Celsius SC - Specific conductance. in micromhos per centimeter at 25°C ALK - Total alkalinity as calcium carbonates in milligrams per liter FC - Fecal coliform bacterias in colonies per 100 millilitars FS ~- Fecal streptococci bacterias in colonies per 100 milliliters DPW - Virgin Islands Department of Public Works VIHA - Virgin Islands Housing Authority USDA - United States Department of Agriculture NO2 - NO2 + PO4 - TOC - TOS - PO - cvI - USNPS Nitrite as nitrogens total NO3 - Nitrite plus nitrate as nitrogens total/ mitigrams Phosphorusv orthophcsphate per liter Organic carbone total Total dissolved solids No data Privately operated College of the Virgin Islands - United States National Park Service are shown in tables 1 to 5. The principal findings of the reconnaissance were as follows: 1. Specific conductance values normally ranged from 1,400 to 3,000 micromhos per centimeter (umhos/cm). Well numbers 6 and 9 had values which surpassed 4,500 umhos/cm. 2. Fecal coliform and fecal streptococci bacteria were detected in samples from 18 of the 19 wells sampled. Colony counts of fecal streptococci bacteria were as high as 5,800 colonies/100 milli- liters (mL) of raw water sampled. 3. Nitrate concentrations exceeded 1.0 milligrams per liter (mg/L) at ten of the wells sampled. 4, Chloride concentrations generally ranged from 180 to 600 mg/L. At 13 wells (map numbers 1, 4, 5 tone gos LO, 12° v3, 15, 17, .and 18)3 chiloride concentrations exceeded drinking water standards of 250 mg/L (EPA Drinking Water Regulations). 5. Sulfate concentrations for most wells were less than the drinking water standard of 250 mg/L. All the wells sampled had total dissolved solids exceeding the EPA secondary drinking water standard of 500 mg/L. 6. Concentrations of organic compounds and most trace elements at selected sites were less than detection limits. Additional information about the wells sampled and the data in this report is available from the U.S. Geological Survey, Water Resources Division, Caribbean District office in San Juan, Puerto Rico (Tel. (809) 753-4414). B50 08 SE pO8 Js 64° 50’ | 18°24'}— S Sy ~ ST. THOMAS pa 18°201— na Q.1 2 9 4mites de | | | | COASTAL EMBAYMENT Ki PRI SAMPLED WELL SITE 17°45’ 17°40’ EXPLANATION 18°22" AQUIFER = VOLCANIC ROCKS AQUIFER NGSHILL AQUIFER o'8 WELL SITE @'? ORITY POLLUTANTS 18°18' se eo Sa538 ST. CROIX 0 1 2 3 4 MILES eS) aes ea La Figure 2.--Principal aquifers and selected wells sampled in the U.S. Virgin Islands. Table 2.--Concentrations of dissolved common ions and trace elements from selected wells in the U.S. Virgin Islands, July 1984. COMMON IONS, DISSOLVED TRACE METALS, TOTAL WELL (MILLIGRAMS PER LITER) (MICROGRAMS PER LITER) INUMBER ON MAP| Ca Mg Na K $04 Cl F sid2 TDS As Ba Cd Cr Pb Hg Se Ag 4 67 48 280 0.9 99 270 0.6 4&7 1159 2 4100 1 2 2 a ees 3 <1 Pid 37 36 250 =? 55 190 =O 38 919 2 < 100 1 2 2 0.6 2 <4 3 400 29 92 eg 33 170 oo 37 610 2 106 1 6 2 0.5 4 Soon 4 21 10 5990 8.0 170 460 <0 28 1640 = == a — —— == <a =e 5 220 10 750 MATE 270 1500 <2 40 3190 2 200 1 2 1 0.6 4 1 6 120 65 420 624 190 600 Pr) 36 1670 == = <= == == zai ce a ie A 55 42 440 4.5 55 490 8 38 1390 4 < 100 1 <1 1 0.4 1 <4 8 120 81 679 mie 220 1100 Pe 33 2460 A < 100 <1 < 14 <4 124 8 <1 9 71 46 230 1.4 €1 160 28 45 977 1 < 100 1 5 S < - O54 2 Sit 10 66 83 340 ceo 99 440 =o 46 1410 4 < 100 41 5 1 0.2 3 <4 11 39 32 230 29 44 180 28 48 861 41 < 700 4 4 1 0-5 3 <4 12 37 24 339 28 72 330 5) 34 4090 4 <€ 100 1 3 < 4 Uys 2 <4 13 40 43 370 129 90 410 at 2? 1320 << oe == ee ca = = —— 14 16 13 220 «8 32 230 ae 35 696 1 < 100 q 4 4 0-5 4 <4 15 180 62 289 6.9 200 390 1.1 33 1460 == == == == == =< —— == 16 77 64 230 3.3 42 370 aS 36 1120 1 < 190 u 4 1 0.4 1 <4 a 41 46 2990 Sat 120 430 aS 36 1140 4 < 10C 2 5 <1 Uses 1 <4 18 100 TS 360 2e2 67 490 a5 38 1460 1 < 100 Ps 6 1 0.6 |< 1 <1 19 66 54 180 See 30 130 =o 40 859 == =—— = —— == iar oo = E X P L A N A i I Oo N Ca - Calciun K ~- Potassium F - fluoride As ~ Arsenic Cr - Chromium Se - Selenium Mg ~- Magnesium $04 - Sulfate $iG2 - Silica Ba - Barium Ph - Lead Ag - Silver Na ~- Sodium Ci - Chloride TOS - Total dissolved solids Cd - Cadmium Hg - Mercury == ~ No data Table 3.--Concentrations of priority pollutants at selected wells in the U.S. Virgin Islands, July 1984. NUMBER Al Sb As Be Cd cr Cu Fe Pb Li Mn Hg Mo Ni Se Ag Zn CYANIDE ON MAP 01 4 790 <1 2 < 10 <4 < 16 <9 < 10 4 10 < 10 0.1 2 7 ee | 4 nie 10 < Os Y \<- 170 <1 <4 < 10 <4 < 10 <4 10 2 50 5 ae |e 8 a <4 2 6 <1 10 <4 04 14 10 | -- £65 1.22 -- 11 Tar | & 410 <4 180 -- < 10 -- -- 2 13 < 2041 16 19 4 -- <a 1.5 -- <4 5 236 < 10 < 4 17 == < 10 —— sist 1 190 < 04 19 20 <4 x4 < 10 S19 < 10 5 | < 10 q <4 <-96 | ae | 1 4 < 4 21 < .01 E xX P L A N A T | Oo N Cu ~ Copper Fe - Iron Pb - Lead Be ~ Beryllium Cd - Cadmium Cr ~- Chromium Al - Aluminum Sb ~- Antimony As ~ Arsenic Concentrations in micrograms per liter Li - Lithium Mn - Manganese Hg ~ Mercury Mo Ni Se Concentrations in milligrams per liter Cyanide Ag - Silver in - Zinc -- - No data - Molybdenum - Nickel - Selenium at Table 4.-- Purgeable organic, base-neutral, and acid extractable compounds for which analyses were performed in samples from five wells in the U.S. Virgin Islands, July 1984. 173-Dichlorepropene Ethylbenzene Methylbromide Methylene chloride 2-Chloroethyl vinyl ether Chloroform Dibromochloromethane Dichlorobromomethane Jichlorodifluoromethane Benzene 101-Dichloroethane Bromoform 1/2-Dichloroethane Carbon tetrachlorice 17/1-Dichloroethylene Chlorobenzene 17/2-trans~Dichloroethylene Chloroethane 1/2-Dichloropropane Tetrachloroethylene Tol 1Ieieinmtrichloroethane Ivis2-Trichloroethane Trichloroethylene Trichlorofluoromethane Vinyl chloride Ieie2e2-Tetrachloroethane Minimum detection limit 3.0 micrograms per liter uene Benzo (b) fluoranthene 104~Dichlorobenzene B3enzo (k) flucroanthene Diethyl phthalate Benzo (€grehei)d perylene Dimethyl phthalate Benzo (Ca) pyrene Di-n-butyl phthalat 2724-Dinitrotoluene 206~Dinitrotoluene 4~Bromophenyl phenyl ether Butyl benzyl phthalate bis (2-Chloroethoxy) methane Di-n-octylphthalate bis €2-Chlorethyl) ether bis (2-Chloroisopropyl) ether 2-Chioronaphthalene 4-Chlorophenyl phenyl ether Fluoranthene Flucorene Hexachlorobenzene Acenapthene Chrysene Acenapthylene Dibenzo (ash) anthracene Anthracene 172-Dichlorobenzene Benzo (a) anthracene 173~-Dichlorobenzene e bis C2-Ethylhexyl)phthalate Hexachlorobutadiene Hexachlorocyclopentadiene Hexachloroethane 476-Dinitro~2-methylohenol Indeno (12/3) pyrene 24-Dinitrophenol Isophorone 2~“Nitrophenol Naphthalene 4-Nitrophenol Nitrobenzene Pentachlorophenol Phenol n-Nitrosodi-n~propylamine n-Nitrosodimethylamine n-Nitrosodiphenylamine Phenanthrene Pyrene 1e2e4-Trichlorobenzene 4-Chlioro-3-methylehenol 2-Chlophenol Minimum detection limit 1.0 micrograms per liter 274-Dichlorophenol 204-Dimethylphenol 204e4-Trichlorophenol 2e3e7r8-Tetrachlorophenol 4-8romophenyl phenol 373-Dichlorobenzid All concentrations were below minimum detection level. Table 5. Organochlorine insecticides, polychlorinated byphenils, and polychlorinated naphthalenes for which analyses were performed in samples from five wells in the U.S. Virgin Islands, July 1984. Minimum detection level 0.01 micrograms per liter ALDRIN dDD DDE ODT OIELDRIN ENDRIN ENDOSULFAN HEPTACHLOR HEPTACHLOR EPOXIDE LINDANE METHOXYCHLOR MIREX Minimum detection level 0.1 micrograms per liter CHLORDANE GROSS POLYCHLCRINATED BIPHYNELS CAS PCB) GROSS POLYCHLORINATED NAPHTHALENES CAS PCN) AROCHLOR 1016 AROCHLOR 1221 AROCHLOR AROCHLOR AROCHLOR AROCHLOR AROCHLOR 1232 1242 1248 1254 1269 PERTHANE Minimum detection level 1.0 micrograms per liter TOXAPHENE All concentrations were below minimum detection level. REFERENCES Brown, E., and others, 1970, Methods for the collection and analysis of water samples for dissolved minerals and gases: U.S. Geological Survey Techniques of Water Resources Investigations, Book 5, Chapter Al, 160 p. Classen, H.C., 1982, Guidelines and techniques for obtaining water samples that accurately represent the water chemistry of an aquifer: U.S. Geological Survey Open-File Report 82-1024, 49 p. Cosner, O.J., 1972, Water in St. John, U.S. Virgin Islands: U.S. Geological Survey Open-File Report, (unnumbered). Goerlitz, D.F., and Brown, E., 1972, Methods for analysis organic substances in water: U.S. Geological Survey, Techniques of Water Resources Investigations, Book 5, Chapter A3, 40 p. Greeson, P.E., and others, 1977, Methods for collection and aquatic biological and microbiological samples: U.S. Geological Survey, Techniques of Water Resources Investigations, Book 5, Chapter A4, 332 p. Jordan, D.G., 1975, A survey of the water resources of St. Croix, U.S. Virgin Islands: U.S. Geological Survey Open-File Report, (unnumbered), 51 p. Jordan, D.G., and Cosner, 0.J., 1973, A survey of the water resources of St. Thomas, U.S. Virgin Islands: U.S. Geological Survey Open-File Report, (unnumber- ed), 55 p. Robison, T.M., and others, 1972, Water records of the U.S. Virgin Islands, 1962-69: U.S. Geological Survey Open-File Data Report, 163 p. Skougstad, M.W., and others, 1979, Methods for determinations of inorganic substances in water and fluvial sediments: U.S. Geological Survey, Techniques of Water Resources Investigations, Book 5, Chapter Al, 626 p. The National Drinking Council, 1977, Drinking water and Health: National Academy of Sciences, Washington, D.C., 1977, 939 p. Torres, H., and Dacosta, R., 1984, Estimated water use in St. Thomas, U.S. Virgin Islands, July 1983 to June 1984, U.S. Geological Survey Open-File Data Report 84-721, 1 pl. - Environmental Protection Agency, Drinking Water Regulations: 40 C.F.R., Part 141. TECHNICAL REPORT NO. 20 CARIBBEAN RESEARCH INSTITUTE COLLEGE OF THE VIRGIN ISLANDS ST. THOMAS- U.S.VIRGIN ISLANDS 00802 PROJECT NO. 375003 AGREEMENT NO. 14-08-0001-G-875 THE RESEARCH ON WHICH THIS REPORT IS BASED WAS FINANCED IN PART BY THE UNITED STATES DEPARTMENT OF THE INTERIOR AS AUTHORIZED BY THE WATER RESEARCH AND DEVELOPMENT ACT OF 1978 (Pil. 950467). U.S. GEOLOGICAL SURVEY WATER RESOURCES DIVISION CARIBBEAN DISTRICT SAN JUAN, PUERTO RICO