wewese Ty i WATER QUALITY OF CISTERN WATER IN ST. THOMAS, U.S.V.I. A. Preliminary Survey F. Rinehart, R. Peebles, P. Hoffman B. Microbial Analysis and Major Ion Composition M. J. Canoy, A. Knudsen Project No. A-010-VI Agreement No. 14-34-0001-1150 September 1983 The work upon which this report is based was supported in part by funds provided by the United States Department of the Intertor, as authorized by the Water Research and Development Act of 1978 is Technical Report No. 2+ Caribbean Research Institute College of the Virgin Isiands St. Thomas, USVI 00802 [ r r r ~ [ [ [ i: r [ [ DISCLAIMER Contents of this publication do not necessarily r reflect the views anc policies of the U. S. [ Department of the Interior, nor does mention of trade names or commercial vroducts con. ui sti tute [ their endorsement or recomnendations for use by [ the U. S. Government. . ° L - 3 9 9 ABSTRACT A study in two phases was conducted in the Virgin Islands to determine the major ions and microbial species in the cistern water of the U.S. Virgin Islands. The first phase was a survey of a sample set of cisterns to determine the scope and limits of the problem. The second phase was an indepth study of bacterial species and eight ion species. A significant proportion of water supply in the U.S. Virgin Islands comes from the rainfall which is stored in cisterns. All dwelling units are required by law to have cisterns. Since cistern water is not part of the public distribution svstem, it is not covered by the Safe Drinking ater Act (Public Law 93-523). The objective of this study was to determine whether cistern water supplies pose a potential health hazard to their users. Cistern water supplies were studied to assess the types of heterotrophic bacteria and ion species that may be present. The bacterial study was directed towards identifying those organisms capable of causing disease in water supplies. Total coliform, fecal coliform, fecal streptococcus, and Salmonella/shigella spp. were enumerated. The presence of coliform bacteria, fecal streptococcus, and Salmonella/ shigella spp. in most of the cistern water supplies suggest potential health problem. There was no clear pattern of con- tamination found; however, the general prevalence of contam- ination suggests potentially dangerous chronic infection from several possible sources and the levels of contamination were higher in public housing projects, located near main roads, and where trees overhung collection surfaces. Generally the levels of metals contamination found were well within the Public Health standards. Very few of the private cisterns however met microbial standards. Only three of the public housing tests met the legal health standards, and two of those had high Salmonella/shigella test results which meets “legal" standards but may be more significant health-wise. A recommendation is made to carry out a detailed study of contamination types, levels, and sources for water supplies in the Virgin Islands. Also suggested is creation of a local law regulating the quality of all water for sale and all cisterns. Such water sources are not now controlled. iii re rr rn nr 7 — 79 a) p) 4a TN ACKNOWLEDGEMENTS We are grateful to two chemistry students at the College of the Virgin Islands, Miss Leslie Dewar and Mr. Auckland Isaac, who have made technical contributions to the project, Mr. Lorden Warrington, Student Assistant in the CRI Environmental Laboratory, and Mr. Kim G. Stearman, of CVI Agricultural Extension Service, for metal analysis. We are thankful also to the Administrative Staff of CRI, especially Miss Cynthia Rymer, for typing and proofing the final manuscript. - iv a | oy a —~ oJ “FJ FD a TABLE OF CONTENTS Abstract Acknowledgements List of Tables List of Figures Setting Introduction Characteristics of Household Cistern Systems PHASE I Methods of Analysis Results Conclusions PHASE II wee ee ee ee ek kk ee Sampling and Analytical Program Results Discussion Conclusions Recommendations References Page iii iv vi vii 10 15 23 25 31 46 47 50 LIST OF TABLES Page PHASE Table Geographical Distribution of Study Sites 10 Table Most Probable Number Index 12 15 fA Table Cation Detection Limits/ppm. Table Chemical Analysis. 19 Table Bacterial Assays 20 “ . = Table 6A Total Bacterial Count Table 6B Total Coliform Count 21 Table 6C - fo) Total Streptococci Count Table 6D Total Salmonella sp. Count 22 PHASE II Table Media 29 Table Bacterial Profiles for 100 Cisterns 32 rf Table 37 pH and Metal Ions Table Drinking Water Guidelines and Regulations 39 ' Table Chemical and other Characteristics of Cistern and other Water Supplies for 42 St. Thomas, Virgin Islands Table Analyses of Water of St. Thomas 43 | vi LIST OF FIGURES Page PHASE I Figure 1 The U.S. Virgin Islands Location Map . 2 PHASE II Figure l Sample Flow Sheet for Water Analysis .. . 28 vii re rr nr nr ~ 3 a re ne | | 3 E) ~— ya 3 OF OD ~ "> SETTING St. Thomas, a Caribbean island in the U.S. Virgin Islands, relies on a variety of sources for its domestic water supply. In the early 1970's, these sources included wells on the eastern part of the island, three desalinization plants, water barged from Puerto Rico, and a large number of individual household cistern systems. At one time, large municipal cisterns were operating, however, these systems have not been maintained and were functioning only at the College of the Virgin Islands during this study. Duplicate water samples were collected from over 130 household cisterns as well as from other sources of domestic water on the island. THis paper presents the results-of the chemical and microbial analyses. done on these samples and discusses the type and water quality of household cistern water supplies for domestic use. St. Thomas is 4.8 km (3 miles) wide and 19 km (12 miles) long. It has a backbone ridge of mountain which rise to approximately 457 m (1500 ft.) above sea level. The climate of St. Thomas is essentially marked by constant easterly trade winds and maximum average temperatures about 27°C (80°F) in the winter an OO. SC to 352°C (§7-8S°F} during the Summer. Average relative humidity is above 80%. Rainfall fo] f. Ly OCE4N GULF OF MEXICO \)e “ aTLanric ee’ BAHAMAS q CUR HAITS: CaiTEDOMIN IC AN ne a ll HONDURAS “<> ane wine * wre wi BRITANICA JAMAICA a ae) “HONDURAS | CO4RIBBEAN SEA 14 — ~ EL SALVAD NICARAGUA A D PACIFIC ~ oH Lg OSTA\ Sfrainiap OCEAN ICA) COLOMBIA) —_ VENEZUELA al RL RE i ATLANTIC OCEAN ST. THOMAS 5 CHARLOTTE AMALIE SAO, ST. JOHN CARIBBEAN SEA > 4 CHRISTIANSTED FREDERIKSTED ST. CROIX fs THE U.S. VIRGIN ISLANDS 4 LOCATION MAP Fig 1 2 ~ | ~~3 ar) ar) —. ee) frequently occurs in the form of brief showers, with the higher elevations on the island tending to receive greater amounts of rainfall, on the order of 102-186 cm (40-80 in.) per year. Average monthly rainfall for the month of December through June is 5 to 7.5 cm (2-3 in.), while for July through November it is on the order of 10 to 12.5 cm (4-5 in.) of which 80% is during July and November. The population of the Virgin Islands is approximately 110,000 persons, having doubled in 15 years and being ex- pected to double again in the next 10 years. The water problem is expected to parallel oT exceed this growth rate. 4 a) “3 93 | ~~ 3 ~~ 3 a re re a ne) “~~ a) a re INTRODUCTION Fresh water has always been in critical supply in St. Thomas. Rain collected on roofs and stored in cisterns is still the source of water for most rural and urban domes - tic supplies. Before 1960, hillside rain catchments and a few dug wells were the major source of water for public supplies. Since that time desalted water barged from Puerto Rico, was a close second until 1981. Barging has been discontinued for years at this time. i) Charlotte Amalie has a dual public water system. Fresh water is used for drinking anc general household needs, and Salt water is used for sanitary and fire-control purposes. The fresh-water supply is obtained from salt-water distilla- tion plants, hillside rain catchments, and wells. In the late 1950s, with the exception of 1957, a drought year, catch- ments were the major source of water. Barged water became the major source of supply in the early 1960s, but by the jate 1960s, desalted water became the principal source of supply. At the time of sampling, these desalinization plants were producing only 2.5 mgd. Since the desalinized water, well water, and water barged in from Puerto Rico were likely to be of markedly cifferent chemical composition, the com- position of the domestic waters of Charlotte Amalie could be somewhat variable. ae) rr ee rr rr ce | | Rooftop catchments and cisterns are still the major source of water for rural St. Thomas. During prolonged dry periods, rain water is supplemented by water hauled from public-supply points in Charlotte Amalie. Small ponds have been constructed, tapping storm runoff for irrigation water for trutk gardening and drinking water for stock. Since 1962 about 40 wells have been drilled, but these are not systema- tically pumped,and many are contaminated from inadequate septic tank leaching fields or storm runoff. This study represents a follow-up of critical directions indicated by Isquith and Winters (1981), and Lee and Jones (1982). These studies indicated that wells were heavily contaminated,and at least some. cisterns were no better. A preliminary study done by Rinehart, et al, as a guide to areas of concern has been described under Phase I of this report. The Rinehart report showed problems existed but called into question the two other reports in terms of degree and extent. Phase II explores the degree, nature, and possibie pattern of contamination. The conclusions and recommendations > are aimed at local interests and management as well as water resource scientists. 4 “a 3 a) a) a) 9 —y CHARACTERISTICS OF HOUSEHOLD CISTERN SYSTEMS Many of the homes in St. Thomas are constructed in such a way that all,or at least a substantial part, of the roof collects rain water and transports it to storage tanks located within or below the house. Debris that collects on a roof accumulates in the storage tank along with the rain water. The water from this tank is used to meet most house- hold needs. Some residents find that for a variety of reasons the cistern water supply is inadequate to meet the needs of the household. Supplemental water can be purchased from a private water supplier who delivers water via truck to the cistern systems. The trucked water was, at the time of this study, derived primarily from wells that had been found to have elevated coliform counts, even though the water from these wells was chlorinated. Private trucks also deliver desalinated water from government stand pipes. There are no restrictions on the composition of the cistern roof collection systems or their paint. The cistern tanks were composed of various materials, including painted and unpainted concrete, galvanized metal, sheet-rubber lined concrete and fiberglass. The existing roof collection systems also varied widely in their construction and composition. Some were galvanized iron, usually painted with red lead paint within a fex years after construction. Others were terr 134) cotta tile, concrete, or plywood covered with tar paper | 3 a a re a) a ee 3 ~~" and coated with hypolon. The roofs of many of the newer homes were constructed of fiberglass-desco which was periodi- cally painted. There are several types of paint used frequently for roofs on this island. One is an "asbestos fiber/liquid aluminum" paint containing 4% asbestos and about 18% titanium dioxide. Other paint used frequently contain zinc oxide or tributy] tin oxide for controlling mildew, while many roofs are surfaced with neoprene rubber and "Hypalon". There has been some concern in the past about the use of paints con- taining mercury on roofs that are part of a roof-cistern system. A few cisterns were screened to exclude frogs, lizards, rats, but most either were not or else the screens were rusted or displaced. Survey studies by Isquith and Winters (1981) and Lee and Jones (1982) indicated potential problems with microbes, algae, and protozoa. ~~! [ PHASE I] [ [ [ PRELIMINARY SURVEY [ [ by [ Frank P. Rinehart Patricia A. Hoffman Division of Science and Mathematics [ Al and : Roger Peebles Caribbean Research Institute [ College of the Virgin Islands St. Thomas, U.S.V.I . 00802 [ [ ( [ a nr | ~ "> 3 a) Tan) er ee os ~~" fae PHASE I] Drinking water in the U.S. Virgin Islands is “available in limited supply and is often of questionable quality. Water in private homes, schools and public housing is usually stored in cisterns and comes from one of three primary sources: desalinized water delivered through a leaky distribution syster or by trucks, ground water piped to the surface end delivered by trucks, and rainwater collected on tne roof of each building and delivered to its cistern through gutters. Each source of water has known,or potential, public heeith dangers associated with it. The distribution system for Gesalinized water, for instance, is known to be leaky and to share routes with a , sewage collection network also known tc be leaky. Ground water sources are also prone to contamination, not only from sewage seepage, but from salt water intrusion. Trucking water for home delivery involves transfer prczsedures which are also potential public health hazards. Collected rainwater might also be contaminated from a variety of sources. It contains atmospieric dust and aerosols, accumulated dust and debris from roofs, breakdown products from roofing materials, organic debris from :verhanging trees, micro- organisms, fecal material from rodents, birds, and lizards, 3 3 "9 E) and salt deposited from sea spray. During storage, it inter- acts with cistern walls. Frogs may visit or reside in the cistern. Under special circumstances, the cistern itself can be subjected to ground water seepage. This paper describes a preliminary study done on the quality of collected rainwater stored in the cisterns of private homes. Cisterns selected for study were known to have received only rainwater for at least the previous two years. While study sites were selected from areas all over the island, no special attempt was made to document water Guality such as sites near the Bovoni Dump or close to heavily- traveled roads. The intent of the study was to characterize the quality of water collected and stored under the best circumstances. Samples were tested for chemical composition and bac- terial contamination by a variety of standard methods. Water was tested for total solids, conductivity, chloride, nitrate, calcium, magnesium, iron, copper, and, 10 some cases, lead. The total concentration of bacteria of all types was determined. The concentration of coliform bacteria, an indicator of the possible presence of pathogenic bacteria, was also measured. Other possible chemital.. and biological tests were not per- formed due to limitations in time or experimental facilities. 3 a rr) a a ne METHODS OF ANALYSIS Sampling Samples were obtained from Private homes around St. Thomas. The geographical distribution is indicated in Table 1. TABLE 1 Geographical Distribution of Study Sites Study Site Number Location 1 Estate Hope, Fortuna 2 CVI, Contant, Solberg 3 Dorothea, Hull Caret, Pearl 4 Charlotte Amalie 5 Frenchman's Bay, Bolongo 6 Bovoni, Nazareth 7 Wintberg, Rosendahl 8 Tutu, Anna's Retreat Each donor was asked to fill out a questionnaire describing the cisterm from which water vas drawn and the roof which collected the water. Each donor collected water samples froma well-used household tap according to written instructions. For bacteriological tests, donors were supplied with a sterile - 10 3 re re re | 3 collecting bottle. If the cistern water had been pre- viously chlorinated, 0.2 ml of 10% sodium thiosulfate was added to the collecting jar before sterilization to de- activate the chlorine. Samples to be used for chemical analysis were collected in treated glass or polypropylene bottles. The treatment consisted of a detergent wash, chromic acid rinse, distilled water rinse, nitric acid rinse, and repeated distilled water rinses. Bacteriological Testing Water samples were tested for total bacterial con- centration and also for coliform bacterial concentration by standard water testing methods. a. Total Plate Count: A total bacterial count was done on each sample. ‘Several dilutions of the samples were made in buffered water. Then, 0.100 ml of each dilution was mixed with 10.0 ml of standard method agar in petri dishes. After incubation in an in- verted position for 48 hours, the number of colonies was determined. Colonies were counted on those plates which had between 30-300 colonies per plate. b. Most Probable Number (MPN) Determination: Lactose lauryl sulfate tryptose broth (LLSTB) was used in a presumptive coliform test. For this test, tubes contained 20.5 ml of the fermentation broth and ii re re | ee ne ee ee ee | 3 er nr rr rr ere inverted Durham tubes, 10.0 ml of the sample was added to each of tubes, the tubes were incubated at 35°C for 24 hours and checked for gas formation. All negative tubes were incubated for another 24 hours and -checked for gas formation. A tube with even a small amount of gas is considered to be a positive indica- tion of gas forming bacteria. From each positive tube, a loopful of material was transferred to a tube containing 10.5 ml of brilliant green lactose bile broth (BGLBB) and an inverted Durham tube for a confirmation test. All tubes were incubated at 35°C for 24 hours, checked for gas formation, and re- incubated for an additional 24 hours if no gas had formed. The MPN index was determined from the number of tubes containing gas-forming bacteria. TABLE 2 Most Probable Number Index Postitive Tubes Index 0 < 2.2 1 2.2 2 S.l 3 c.? 4 1€.0 bs) >16.0 12 a J re re: rn re | | “9 Any index equal or greater than 5.1 is considered a positive indication of the presence of coliform bacteria and is presumptive of the presence of human fecal: material. Confirmation tests were done on any sample for which three or more tubes gave positive indi- Cations of gas formation. A loopful of the BGLBB Culture was streaked on a plate of Levin EMB agar and incubated at 37°C, transferred to LLSTB medium and checked for gas formation after in- cubation at 35°C for 48 hours. Slants were prepared, incubated 18-24 hours at 35°C and Stained with gram stain to check for the presence of gram negative rods, single or in pairs. Membrane Filter Technique: This is a second standard test for the presence of coliform bacteria. 25.0 mil of each sample was filtered through sterilized 0.45 micron gridded filters and rinsed twice with buffered water. Each filter was placed in a petri dish on a sterile pad saturated with about 2 ml of M-endo broth. Inverted dishes were incubated at 35°C and 95% humidity for 24 hours. Total colonies were then counted as were those colonies which appeared dark rec with a green-gold metallic sheen under fluores- cent light. These colonies are indicative of 15 a ae) —4 OT >B re ee “QJ FZ rr ee eee eee coliform bacteria. Filters chosen for counting had between 20-80 colonies of all types. If the number of coliform colonies per 100 ml of sample is greater than 4, it is considered excessive. Coliform bacteria were confirmed by sampling typical colonies and incubating them in LLSTB broth. Tubes which were positive for gas formation were used to innoculate BGLBB cultures which were in turn checked for gas formation. Depending on the number of colonies from the membrane filter verified as coliforms, adjustments in the number of coliform colonies per 100 ml were made. Chemical Analysis Total solids were determined by placing 100 ml of fresh, unfiltered ‘samples in pre-weighed evaporating dishes and evaporated -. over steam. Residues were dried overnight at 105°C before re-weighing. Some samples were also filtered through pre-washed 0.45 micron Milli- pore filters to remove suspended solids prior to evapo- ration. No significant difference between the measure- ment oz total solids and dissolved solids was reliably detected. Conductivity studies were done on fresh samples using @ Beckman conductivity bridge with a calibrated Gip cell. 14 Chloride analysis was done with the Mohr argenometric technique. Nitrate was determined with the standard brucine sulfate colorimetric assay. Cation analysis was done using atomic absorption spectrophotometry. A Varian Techtron Single beam spectro- photometer was used. Samples were stored for extended periods prior to analysis in pre-treated bottles in the presence of distilled nitric acid to prevent adsorption. Minimum detection limits for the determined cations are in Table 3. TABLE 3 Cation Detection Limits/ppm , Ca"* Mp** so pp?* (Fe 2*g Fe3*) Ag* Cu’* 0.02 0.001 0.05 0.05 0.007 0.03 RESULTS Fresh samples usually were Slightly turbid (no direct measurements of turbidity were done) and were often slightly ceiorec, usually golden-brovwn thougn occasionally green. Qualitative statements about suspended solids may be made from the appearance of 0.45 micron Millipore filters 15 [Rey “og ~D 5) a ee eee eee ee: en | 3 after a portion of each water sample had been filtered. The material retained on the filters was, like the solutions, golden brown or occasionally green. Some were not heavily colored, others were and these often clogged. Measurements (not reported) of the weight of retained solids after drying were not consistent. This was in large part due to inadequate experimental measures but also strongly suggested that the dry weight of retained substances was not large. It is likely that bacteria and algae, which would dessicate on drying, are responsible for the bulk of the colored retained material. Results of the chemical analysis on 24 cistern water samples are presented in Table 4. Inorganic substances in cistern water are present in small quantities. - Measurements of total solids (after drying) and conductivity both show the concentrations of dissolved salts to be small. For purposes of comparison, Table 4 also contains a summary of the results of an earlier study (Robinson et al.) on well water. Both means and ranges of measurements on nine wells chosen random- ly from their study are presented. The primary constituent of the solids in cistern water is calcium ion, about 20% by mass. Since cistern water is well-equilibrated with the concrete walls of the cistern, this observation is not start- ling. (Concrete is composed of Carbonate, sulfate, and sd 3} 2: au ny ninosilicate saits of calcium}. Sediur ion is present in large enough quantities to intensely color the flame in 16 4aaa4| aI oll 3 a ees eee eee the atomic absorbtion spectrophotometer. Sodium was not directly measured due to the lack of a suitable method. Chloride is another major constituent (10% of total solids). One obvious source of chloride would be atmospheric aerosols containing NaCl from the surrounding sea. Although not directly measured, carbonates and sulfates are probable important constituents. It is interesting to note that,if one assumes that the chloride is present as NaCl and calcium carbonate, the two would comprise,-on average, about 31 mg/1 of sample, or about 60% of the total solids. Measurements of heavy metal content of cistern water were done for only a few metals, lead, cadmium, silver, iron, and copper. Only copper and iron were found in anv of the samples and only in very low concentrations. Iron could leach from cistern walls or from plumbing. Copper is also likely to leach from plumbing. It should be remembered that all samples were collected at the tap. Nitrate concentrations were small. It may be significant that the cistern with the largest nitrate concentration (&.1 mg/1) was also found to harbor a large concentration of bacteria. Bacterial assays are reported in Table 5. Two diitferent types of assavs were done. The first estimates the total mumber of bacterie present in the semnle. There is no ec- cepted limit for totai bacteriel count in drinking water. ~~ 3 “3 7S 3 re rr ne re es: er ne Second, an estimate of the concentration of coliform bacteria was made by two methods. The most probable number assay relies upon the gas-forming characteristic of coliform bacteria. Five tubes of diluted sample were examined for the presence of gas bubbles. If two or more éontained gas,- coli- forms were subjected to confirmatory tests. A separate estimate of the number of coliform bacteria was obtained by trapping bacteria on a membrane filter and culturing them in conditions favoring growth of coiiforms. Any suspect coli- form colonies were subjected to confirmatory tests. Four or more coliform bacteria per 100 ml of water is unacceptable. Ox the 30 cisterns tested, only four were contaminated by either of these standards. There is no clear correlation between total bacterial count and the presence of coliforms in these samples. Al- though three of the four cisterns with large coliform counts also had very large total bacterial concentrations (29,000, 58,000 and 92,000 bacteria per ml), one (sample 3.6) had a relatively low concentration (2,100 bacteria/ml). In addi- tion, several cisterns with relatively large numbers of bacteria had no detectable ccliform bacteria, e.g. 2.5, 4.2 No attempt was made to identify bacteria other than coliforms at this stage of the Study. Many samples containec nmon-coliforr, be fan) m4 rj as) ie] ct ww 3 49 lon 3° we teria, most likely Aerobacter, a@ soil bacterium. No measurements of algae or unicellular organisms were attempted. 1& a o TABLE 4 Chemical Analysis Concentrations in mg/l (ppm) Sample Solids Cl NO, cat Me 2* Fe ions cu2* Conductivity 1.1 47 5.6 1.37 5.3 0.14 0.15 0.03 70 1.2 37 4.6 1.06 6.6 0.17 0.04 56 2.4 60 7.7, 1.76 53-9 0.13 0.16 94 2.5 75 ND 0.24 10.4 0.56 ND ND 75 3.1 75 5.0 1.51 9.5 0.40 ND 0.01 139 3.2 38 4.6 1.00 7.2 0.15 0.07 68 3.3 33 4.6 1.06 6.5 0.24 ND 0.01 75 3.4 24 4.5 0.85 4.6 0.39 ND 0.04 49 3.5 53 4.9 0.91 7.0 0.25 ND 69 3.7° 53 8.4 0.94 10.8 0.17 0.06 0.06 99 3.8 31 5.5 0.91 6.5 0.57 ND 62 3.9 39 ND 0.27 1l.1 0.40 ND ND 79 3.10 59 ND 0.32 20.2 1.68 ND ND 136 4.1 56 5.1 10.7 0.19 0.08 4.2 62 3.9 1.14 11.6 0.25 0.12 0.03 81 5.1 49 4.8 1.33 7.3 0.10 0.09 0.04 £8 5.2 27 4.2 0.55 5.8 0.29 ND 0.03 56 6.1 65 5.6 8.2 0.20 0.03 0.03 6.2 54 6.4 1.19 7.5 0.15 73 6.3 39 ND 0.26 9.6 0.73 ND ND 81 7.1 ND 0.22 9.9 WD ND ND 7.2 28 ND 0.22 9.9 ND ND ND 62 8.1 63 4.7 3.68 10.1 0.29 0.10 0.06 89 wells 1079 227 19 49 41 1705 (641- (35- (4.5- (30- (24- (858- 1300) 300) 68) 88) 68) 2200) &. concuctivity in units cf micromhos dD. Not Detected c. this sample has been previously chlorinated d. well water samples, nine samples chosen tandemly from Robinson et al. (ranges in parenthesis) ray vo) “3 TABLE 5 Bacterial Assays Total Coliform Bacterial Assays Sample Assay MPND MFC Roof Construction Environment 1.1 100 0 0 paint, good condition overhang trees 1.2 610 ie) 0 2.1 1,430 0 8) permacoat 2.2 92,000 5 38 . hypalon overhang trees 2.3 25,000 0 0 hypalon overhang trees 2.4 950 1 1 desco clear 2.5 220 ¢) 0 plywood, plastic roof cement clear 2.6 1,800 0 0 permacoat clear 2.7 1,000 0 0 permacoat clear 3.1 10,000 fe) 0 unpainted concrete salt spray 3.2 1,030 0 0 hypalon roof annually scribbed 3.3 1,800 8) 0 paint on insulfoan poor paint 3.4 600 0 0 good paint clear 3.5 1,400 0 0 galvanized overhang trees 3.6 2,100 3 8 desco overhang trees 3.7 22,000 5 tntc4 hypalon overhang trees 3.8 2,900 0 0 galvanized, painted poor paint, overhang trees 3.9 1,100 8) 0 good paint clear 3.10 2,700 ie) 0 concrete overhang trees dust 4.1 1,150 1 0 concrete town, 100 feet from busy street 4.2 16,300 i 1 galvanized, 2 months old paint overhang tree 5.1 3,200 0 0 permacoat overhang tree smoke from auap 5.2 3.000 0) 0 painted metal clea 6.1 6,600 fe) 0 concrete beach, smoke, dust 6.2 20,000 6 0 hypalon, recent birds 6.5 430 0 0 galvanizec, hypalon near lagoon, coated highway 6.4 2,200 1 1 7.1 1,460 1 0 Gesce over plywood overhang trees 7.2 180 0 0 unpeintec ¢géivanizec overhang trees o.i 58,000 5 16 rooizven over Plywood overhang trees a. Bacteria per milliliter of water b. MPN Index (See Table II) c. Millipore filter Assay, coliforms per 100 ri. €. TNTC means “roc numberous to count" 20 higteay a ee a) re rn Pre “jy 3 , ~ 39 ~3 3 “3 " “~~ 3 J TS TABLE 6A: TOTAL BACTERIAL COUNT Bacteria/100ml1 Site Dec. 1979 Feb. 1980 July 1980 Oct. 1980 St. Thomas Bovoni 8.7 x 102 2.0 x 104 5.8 x 10° >1.0 x 10° Smith Bay 7.2x 105 1.5 x 10° 2.4x 107 >1.0 x 10° Coliege of the Virgin Isiands 7.0x 102 7.8x10% 7.3108 >1.0 x 10% Hoff 5.6 102 4.0 x 104 4.0 x 10° 6.0 x 103 TABLE 6B: TOTAL COLIFORM COUNT Coliform/100m1 Site Dec. 1979 Feb. 1980 July 1980 Oct. 1980 St. Thomas Bovoni 9.1 x 10! 2.1 x 104 0 >2.0 x 103 Smith Bay 7.5 x 102 2.1 x 102 0 1.0 x 103 College of the Virgin Islands 2.3 x 102 N.D. 0 >2.0 x 103 Hoi 1.6 x 102 0 j.1 x 105 8.75 x 10° 21 (continued...) TABLE 6C: TOTAL STREPTOCOCCI] COUNT Fecal Strep/100mi Site Feb. 1980 July 1980 Oct. 1980 St. Thomas Bovoni 3.6 x 10)