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HomeMy WebLinkAboutFI Hydrogeologic Report 1990 I I I I I I I I I I I I I I I I I I I HYDROGEOLOGIC REPORT Conducted on Fisher's Island, New York for Fisher's Island Conservancy Fisher's Island, New York APRIL 1990 I I I I I I I I I I I I I I I I I I I I. II. III. IV. V. VI. Table Table Table Table Table Table Table Table TABLE OF CONTENTS Abstract INTRODUCTION A. Purpose B. Scope of Study GEOLOGY A. Introduction B. Previous Work C. Monitor Well Installation D. Sub-Surface Materials E. Environments of Deposition F. Cross-sections G. Discussion HYDROGEOLOGY A. Introduction B. Hydraulic Conductivities C. Water Level Data D. Ground Water Flow E. Ground Water Recharge F. Salt/Fresh Water Interface G. Water Use CHEMICAL ANALYSIS AND WATER QUALITY PROBLEMS A. Introduction B. General Ground Water composition C. Areas of Degraded Quality CONCLUSIONS RECOMMENDATIONS A. Additional Assessment B. Management Practices TABLES 1 - Generalized Stratigraphy 2 - Hydraulic Conductivity Tests 3 - Water Level Data 4 - Average Precipitation 5 - Recharge Rates 6 - Ground Water Budget 7 - Ground Water Contaminant Summary 8 - Proposed Ground Water Monitoring Schedule Paae 1 4 30 50 69 72 I I I I I I I I I I I I I I I I I I I FIGURES Figure 1 - Location of Ronkonkoma and Harbor Hill Moraines Figure 2 - Idealized Distribution of proglacial Environments Figure 3 - Exposure of Proximal Outwash Figure 4 - Close-up of Proximal Outwash Figure 5 - Exposure of Lacustrine Deposits Figure 6 - Close-up of Rhythms Figure 7 - Facies Map Figure 8 - Piper Diagrams PLATES Plate 1 - Island Geology Plate 2 - Geologic Cross sections Plate 3 - Ground Water Contours Plate 4 - Ground Water Chemistry - Stiff Diagrams APPENDICES Appendix A: Driller's logs for homeowners and monitor wells; results from private well owner survey are included. Appendix B: Recovery Test Calculations used to determine the hydraulic conductivity of various sub-surface materials Appendix C: Laboratory analysis sheets from ground water and surface water samples across the island. Appendix D: Kerfoot and Horsley Method for determining the zone of influence for private wells. 1 1 1 1 I 1 I I I I I I I I I I I I 'I Abstract The shallow ground water supplies on Fisher's Island are relatively complex and fragile in comparison to ground water supplies on Long Island and other glaciated areas. An extensive hydrogeologic study on Fisher's Island has concluded that permeable aquifer materials are restricted to thin gravel lenses and sorted outwash sands stratified with relatively impermeable silty clay and glacial till. Hydraulic conductivities of these aquifer materials range from 1 to 100 ft/day. The locations of the gravel lenses are difficult to predict but appear to be related to discrete discharge points of high velocity glacial meltwater associated with the glacial front. Ground water flow is defined by a series of marginally interconnected ground water mounds with ground water flow generally moving from recharge areas located in the center of the mounds to discharge areas located at cell borders. The exact location of recharge areas is difficult to determine due to the abundance of impermeable layers separating the gravel lenses. Average ground water recharge is estimated to be approximately 709 million gallons per year. Ground water withdrawals are difficult to estimate because of the unknown quantities used for lawn irrigation, but the range is estimated between 175 million and 300 million gallons per year (between 25% and 50% of average I I I I I I I I I I I I I I I I I I I annual recharge). Based on the irregular geometry of the aquifers, it is unlikely that 100% of the annual recharge will ever be safely available for use. The shallow ground water should be adequate, however, to provide potable fresh water supplies provided that proper management programs are instituted. The potential for significant additional sources from centralized water supply systems and aquifers is not great. Individual private water supply wells can and should provide most of the water for future development on the island. It is crucial, however, that an appropriate regulatory process be instituted for these private wells to prevent local well interference and water mining and the development of salt water intrusion. Centralized aquifers such as the Middle Farms Aquifer should be protected and used with caution. Monitoring wells in the vicinity of the Middle Farms Aquifer should be tested on a frequent schedule during pumping so that salt water intrusion and aquifer dewatering can be quickly detected, monitored and corrected. Additional recommendations include further exploration for an alternative centralized supply, further ground water monitoring at Picketts Landfill, the Metal Dump and other possible sources of ground water contamination and the institution of an island-wide ground water protection and monitoring strategies stressing conservation and land use policies that will preserve ground water quality and insure that adequate fresh water supplies will continue to be available in the future. I I I I I I I I I I I I I I I I I I I I. INTRODUCTION A. Purpose Fisher's Island is one of four (4) small islands located within the Town of Southold, Long Island. Like all of these islands and much of the Town of Southold, the available fresh water resources are limited and currently under stress of ever increasing development. The inhabitants of the island have used ponded fresh water as a primary source for drinking and irrigation and though the quality of the water has generally been good, future demands will require further development of the island's aquifers. The purpose of this study is to develop an understanding of the aquifers on Fisher's Island and their hydrogeology. Secondly, the study characterizes the nature and present extent of man-induced alterations to the quantity and quality of surface and fresh waters. B. Scope of studv The hydrogeologic investigation consisted generally of the installation of eighteen monitoring wells between May 1988 and June 1989 in various parts of the island. During well installation, the geology of the sub-surface materials - 1 - I I I I I I I I I I I I I I I I I I I was described and carefully logged so that an overall view of the island geology could be pieced together. The hydrogeologic properties of the aquifers were determined by repeated water level measurements and conductivity testing of these wells. Finally, the water quality of the aquifers was determined by laboratory analysis of samples obtained from these wells. The specific objectives of the study were as follows: 1. to determine the extent, thickness and geometry of the important hydrologic features of permeable sediments (aquifers) and impermeable sediments (aquicludes); 2. to determine the hydrologic properties of all the aquifers; 3. to determine the recharge to aquifers by estimating the Island's water budget; 4. to determine the ambient water quality of the aquifers and to locate any threats to aquifer water quality; 5. to estimate the risk of salt water intrusion and severe storm tidal surges on the aquifers; - 2 - I I I I I I I I I I I I I I I I I I I II. GEOLOGY A. Introduction The first step in characterizing the aquifers on Fisher's Island is to define the island's geology. By obtaining information on the location and orientation of coarse and fine grained deposits, the sizes of the aquifers can be estimated and potential water supply well sites can be identified. B. Previous Work 1. Regional Setting: The topography in this vicinity of Long Island is related to the retreat of the Laurentide Ice Sheet during the Wisconsin stage of the Pleistocene (Flint, 1947). As the climate became slightly warmer, the ice sheet reached its maximum southern advance as marked by the Ronkonkoma terminal moraine which stretches across the middle of Long Island eventually connecting up with similar deposits in Martha's Vineyard and Nantucket. A second moraine accumulated to the north of the Ronkonkoma that can be traced from deposits along the north - 4 - I I I I I I I I I I I I I I I I I I I shore of Long Island to the mainline of Rhode Island. This second moraine, termed the Harbor Hill, Charlestown, Buzzards Bay moraine includes the deposits found on both Fisher's and Plum Islands. The configuration of these two moraines is shown on Figure 1. The details concerning the exact origin of this moraine are unclear. Some geologists believe that this second moraine marks a readvance of the Laurentide Ice Sheet (Soren, 1971) while others believe the moraine formed as the ice sheet remained stationary before a later advance (Fleming 1935). The Pliestocene deposits regionally overlie semi-consolidated sand and clay units derived from the north sometime during the Cretaceous Period (Crandell 1962). The bedrock on the Long Island and Southern Connecticut consists of a complexly faulted and deformed sequence of Pre-Cambrian Gniesses and Granites (Rodgers 1985) . 2. Previous work on Fisher's Island: The geology at Fisher's Island was first described by Fuller (1904) who used the lithologic descriptions from a deep bedrock - 5 - ------------------- '" ~ "' c ~ " , ;r .";',.... +~.., J~' - 'Is';:):. .,' I:i':'--;:::-I End moqlne ""^"'- Pr...,med Int.,IOO.t. zonet N t 0 :;IDmiles I , , , , 0 50 km 73' 72' 71' 70' ~Ground Water, Inc. FISHERS ISLAND LOCATION MAP FIGURE ONE _ SKETCH MAP SHOWING END MORAINES FROM FLINT 1971 I I I I I I I I I I I I I I I I I I I well on the island (the Ferguson well) and various surface exposures to define the island's stratigraphy. Bedrock was encountered at 281 feet and the overlying Cretaceous and Pleistocene deposits were differentiated into various sand and gravel units. Fuller (1904) attempted to correlate units discovered on Fisher's Island with units previously described on Long Island, Pennsylvania, Mississippi and Canada. Most noteworthy of these units is the Gardiner's Clay, the name given to the thick clay deposits which are exposed in bluffs and beach exposures around the island. Fuller suggested that the clay is part of a thick clay bed which is traceable through the Long Island Sound area. More recent field work by Upson (1970) has shown that lithologically similar clay units in the Mattituck quadrangle on Long Island pinch out laterally, putting Fuller's correlations into questions. These observations coupled with more recent developments and understanding in glacial geology, put many of Fuller's (1904) interpretations into doubt. However, this initial work provided a scale and starting point for later description on the Island. - 7 - I I I I I I I I I I I I I I I I I I I One significant observation by Fuller was the recognition of deformation features in the surficial deposits suggesting that deposits on the island have been moved from their original site of deposition. This has been substantiated by later workers. A more rigorous inventory of glacial sediments on Fisher's Island was conducted by the united states Geologic Survey in the quadrangle reports of Goldsmith 1962 (New London Quad) and Upson, 1971 (Mystic Quad). These geologists found that the most of the island is covered by end moraine deposits which are composed of both till and stratified drift. Both reports indicate that the end moraine deposits are complex and no attempt is made by either to differentiate till from stratified drift. Goldsmith's mapping of the western part of the island (New London Quadrangle) includes rough stratigraphic descriptions of beach and inland exposures and these descriptions suggest that till generally overlies stratified drift. Upson (1971) notes that the end moraine deposits are underlain by thick clay to silt and sand sub-units which Fuller (1904) deemed - 8 - I I I I I I I I I I I I I I I I I I I the Gardiner's Clay. The clay/sand sub-units reach a maximum of 60 feet thick in beach exposures in the south central part of the island. The lateral continuity of these deposits is not known. Upson (1971) also maps three broad sand-plain deposits which cross the island from north to south. He reports that these units are "predominantly sand". The origin of the deposits is not clear and Upson suggests that they may represent either fillings of meltwater channels or large collapse depressions in the moraine when the retreating ice lay immediately north of the island. Both authors show that the glacial deposits are overlain in places by beach, salt marsh, swamp and minor alluvial deposits of Holocene (recent) age. Goldsmith (1982) reevaluated his earlier mapping to include significant areas of stratified drift on the southwest end of the island. He explained this outwash as glacial stream deposits that extended away from a stagnant ice margin. - 9 - I I I I I I I I I I I I I I I I I I I 3. Plum Island: The work conducted by the USGS matches well with Crandall's (1962) mapping on Plum Island located just to the west of Fisher's Island. Through the description of surface exposures and the installation of monitoring wells, Crandall noted that Plum Island consists primarily of end moraine deposits. Like Goldsmith's mapping on Fisher's Island, Crandall noted that the end moraine's deposits consisted primarily of stratified drift with an upper veneer of unstratified till. Like Upson's sand plains, Crandall noticed a roughly north-south trending channel filled with outwash sand interpreted as meltwater deposition. Crandall also noticed that clay, "tentatively assigned to the Gardiner's Clay" underlies the end moraine deposits. His test borings could not confirm that the clay underlies the entire island, further questioning Fuller's 1904 correlations. 4. Rhode Island: The moraine continues to the east in Rhode Island as the Charlestown Moraine. This - 10 - ~" I I I I I I I I I I I I I I I I I I I section of the moraine was mapped by Kaye (1960) who concluded that downwasting was the major mechanism responsible for sediment deposition. Ridges, mounds and hummocky terrain on the moraine were attributed to ice fracture filling and ice block casts. The resulting stratigraphy is a highly chaotic assemblage of lacustrine, fluvial and till materials deformed largely from the downwasting of the glacier. Although specifics concerning the internal fractures of the moraine are not discussed, this model is still generally accepted for much of the Charlestown section of the moraine (Byron stone, U.S.G.S. personal communication) . C. Monitor Well Installations Monitoring wells were installed to supplement geologic interpretations made by these earlier workers and to obtain hydrogeologic information from any encountered aquifers. The location of these wells are shown on Plates in the back of the report and driller's logs are attached in Appendix A. Three methods were used for monitor well installation: 1. Drive and Wash Method; 2. Auger Method; and 3. Air Rotary Method. - 11 - I I I I I I I I I I I I I I I I I I I Monitoring wells 1 through 9 were installed between May 5th and May 19th, 1988 by the Stephen B. Church Company using the drive and wash method. This method involves driving lengths of casing to the desired depths while washing the casing out after each additional casing length had been driven in. At the desired depth, 1-1/4" diameter well screen was set within the casing and the casing was withdrawn to expose the desired length of screen. Sediment samples were described from the casing wash. The wells were developed using either a pump or an air compressor. Monitoring wells 10 through 16 were installed between October 10, 1988 and April 21, 1989 by Clarence Welti and Associates, Inc. of Glastonbury, CT using the hollow stem auger method. This method involves using a hollow stem auger to bore to the desired depth and installing a 2-inch PVC well with slotted screen through the hollow stem. Samples were obtained by hammering split spoons at 10 foot intervals. These samples were described on-site and saved for future analysis. One additional monitoring well (4A) was installed using the air rotary method. This method involves drilling with a rotating bit with cuttings being removed by constant circulation with air. Samples were described from cuttings that were flushed to the surface. A finished four inch PVC casing well was installed into the boring. - 12 - I I I I I I I I I I I I I I I I I I I D. SUb-surface materials A summary of the geologic materials on Fisher's Island is presented on Table 1. Description of deeper deposits was taken from Fuller (1904), Crandall (1972) and Upson (1971). Shallow material descriptions are summarized from boring logs from monitor wells installed as a part of this project. Alongside such material description is an interpretation of the environment of deposition and unit thickness. Also described in the table are the water bearing characteristics of the sediments determined either by inference to similarly described materials or by on-site hydraulic conductivity testing. Details concerning the hydraulic conductivity testing are given in chapter III. 1. Pre-Cambrian Basement: Pre-Cambrian basement and Cretaceous deposits were not encountered during drilling and are generally not pertinent to this aquifer study. It should be noted that the Ferguson well drilled into bedrock and mentioned by Fuller (1904) functioned as an effective water well and the granitic basement mav contain potential water supplies. The Ferguson well log shows the bedrock was encountered at 281 feet. Assessing the exact nature and yield of the bedrock supply would require additional work beyond the scope of this study. From work conducted at Orient Point, bedrock - 13 - I I I I I I I I I I I I I I I I I I I slopes to the southwest reaching depths of between 500 and 1000 feet. 2. Cretaceous Deposits: Similarly, the Cretaceous sediments may contain abundant supplies of water. Much of Long Island relies on water from these sediments for its water supply. However, Crandall (1962) theorized that the Cretaceous deposits are too deep on Plum Island and probably saline because they lie beneath the thin fresh water lens (the fresh water lens will also be discussed in greater detail in chapter 3). Since bedrock is shallower on Fishers Island, fresh water may extend down to any Cretaceous deposits above the bedrock. This is not based on any hard evidence and, like potential bedrock water supplies, assessing the water supply potential in the Cretaceous sediments would require additional work beyond the scope of this study. 3. Pliestocene Deposits: The potential for high yield aquifers within the Pliestocene deposits or "Glacial Aquifer" varies widely from region to region. Generally, deposits associated with the Ronkonkoma and Harbor Hill Moraines are relatively impermeable in comparison to glacial outwash found between the moraines (Hauptmann, et al., 1989). - 14 - I I I I I I I I I I I I I I I I I I I This study concentrates on potential water supplies in the shallow Pliestocene deposits that can be most easily tapped. Drilling and monitor well installation encountered four (4) general types of material: a. fine to medium sand, moderately sorted with varying degrees of sand and gravel. Roughly encountered in thick layers (over 10 feet thick); b. graded, rhythmic coarse to fine sand and gravel occurring in lenses varying from less than one foot to several feet in thickness; c. grey silt and clay stratified with the thinly bedded coarse sand; d. poorly sorted sand silt and clay with varying degrees of cobbles (glacial till). The distribution of the Pliestocene and recent deposits is mapped on Plate 1. This map is primarily a compilation of the Upson and Goldsmith Reports with some revisions based on field observations. E. Environments of Deoosition Glacial sediments deposited in association with - 15 - I I I I I I I I I I I I I I I I I I I Discharge Point Glacial Till Marginal Outwash Facies Distal Outwash Facies Proximal Outwash Facies Medial Outwash Facies i\GroundWater, Inc. FISHER'S ISLAND FACIES MODEL FOR PROGlACIAl ENVIRONMENTS -BASED ON BROZIKOWSKI AND LOON (1987), FRASIER AND COBB (1982), ANDERSON (1982) - 16 - I I I I I I I I I I I I I I I I I I I recessional moraines can most conveniently be subdivided into glacial till, marginal and proximal outwash deposited close to the glacial front and medial (Edwards, 1978 and Anderson, 1989) and distal outwash deposited further away from the glacier (Anderson 1989, Brozicowski and van Loon, 1987, Frasier and Cobb, 1982). Figure 2 shows the distribution of sedimentary facies encountered in morainal or "proglacial" environments. Proglacial environments are dominated by high competence and capacity streams exiting the glacier. At the discharge points these streams deposit very coarse and laterally discontinuous gravel deposits. On either side of the discharge points are thick deposits of glacial till. As the streams flow away from the glacial front they lose velocity and finer materials are deposited. This sorting results in more laterally continuous and finer grained materials moving away from the moraine. Ice damming and damming related to previous moraines can cause ponded water to be located adjacent to the glacial front. This may cause coarse materials to be interstratified with fine grained lacustrine deposits. The poorly sorted sand, silt and clay with abundant cobbles is interpreted as glacial till deposited directly from glacial ice with no meltwater involved. This till forms the core of the moraine that accumulated as the ice front remained stationary. - 17 - I I I I I I I I I I I I I I I I I I I The coarse to fine sand and gravel deposited in lenses is intimately associated with grey silt and clay and together these deposits represent the "marginal" deposits. The sorting and abrupt grain size changes are caused by rapid variations in water flow from the glacier and by direct deposition of gravels into lacustrine environments. The fine to medium sand, moderately sorted with varying degrees of gravel represents proximal outwash deposited a larger distance away from the glacier. These sediments were more likely deposited by braided streams which deposited thicker and more consistent layers of coarse sand. F. Cross-Sections Four cross-sections have been constructed connecting the borings from this study of these materials (Plate II). The lines of cross-section are shown on the maps enclosed as plates in the back of the report. section A-A' is drawn roughly west to east across the spine of the island and three shorter cross-section trending roughly north-south cross the island as follows: in the North Hill/West End of the island (B-B'), central Middle Farms area (C-C') and the east end (D-D'). Lithologic descriptions from test wells drilled for the - 18 - I I I I I I I I I I I I I I I I I I I Fisher's Island Country Club by S. B. Church were used in constructing 0-0' and the eastern section of A-A'. The western end of the island is made up of till and brown sorted sand deposits overlying the interbedded silts and gravels of marginal outwash materials. The brown fine to medium sand of the marginal outwash makes up a large thickness of the western part of the island with glacial till interfingering in places. The uppermost deposits contain glacial till, as noted in the upper parts of the Lamborne and Nitze wells. This overlying till was also observed by earlier USGS Mapping and by Crandall on Plum Island. Deeper till zones were encountered in MW-ll, MW-6 and MW-7. The proximal outwash materials are best exposed in the south shore face to the east of the Hay Harbor Golf Course. See Figures 3 and 4. Here the outwash shows classical glacial delta features including a general coarsening upward grain-size trend. Outwash at the base of this exposure is stratified with silt and clay suggesting deposition into ponded water. The upper, coarser part of the delta is capped by a thin till zone noticed on much of the Island's western end. - 20 - --- -:.-- ,.~,-~, I I I I I I I I I I I I I I I I I I I The marginal outwash below the till contains some thick gravel zones as noted in MW-6 and 11. These gravels may not be laterally continuous as suggested by the interfingering of thin gravel lenses in the Nitze well with the thicker gravel deposit of MW-ll. Moving eastward, the thickness of till increases while the overlying thickness of medium to fine sand decreases. Much of the island between Barlow Pond and Mt. Prospect appears to be underlain by a thick sequence of till. A small thickness of marginal outwash appears in MW-4 as grey silt to clay at thirty and forty feet below land surface. A thick section of gray lacustrine clay (first described by Fuller 1904 as the Gardiners clay) underlies the till. Exposures of this clay can be found at Isabella beach (se Figures 5 and 6). Cuts into this clay show vary fine laminations and gradings from brown dense clay laminate to grey green fine silt and sand. These features are typical of lacustrine sedimentation. Some exposures show highly chaotic deformation of the clay from either slumping or ice tectonism. Generally, no thick gravel zones were encountered in this area. The overlying till pinches out moving into the Middle Farms Pond area. The brown silty sand thins slightly in comparison to wells drilled west of Barlow pond. More importantly, a thick sand and gravel layer, approximately - 21 - . ~:.1,~"i'! I I I I I I I I I I I I I I I I I I I forty feet thick was found in the center of the Middle Farms flats. This aquifer was the subject of intense study by Ground Water, Inc. during the installation and permitting of 2 public drinking water supply wells. The aquifer is confined by silts above and below, and is interpreted to represent a large channel in the marginal outwash materials. The channel could be traced laterally to monitor wells lA and to other monitoring wells installed for the pumping tests. However, the channel could not be traced to MW-2A, 20 and 9, suggesting that the channel is of limited extent in a north/south direction in the Middle Farms area. The Chocomont area is mantled with a thick layer of till as noted in the Schmidt well and MW-l6. MW-l6 did not completely penetrate the till but the log of the Schmidt well suggests that the area is underlain by gravels and silts of the marginal outwash. A thin outwash channel has been carved in the till in the vicinity of MW-8 in the vicinity of East Harbor and shallow ground water is confined to the brown proximal outwash sands. However, unlike the Middle Farms outwash channel, no gravels from the marginal outwash facies were encountered. The till reaches its greatest thickness in test wells drilled by S. B. Church in the eastern end of the - 23 - C7----~:':c:::;;- ',,;' ~~--c--.C7--~",~~---~~'-~:-~C~"- I I I I I I I I I I I I I I I I I I I island. A thick mantle of brown outwash sands overlies the till, and stratified ice contact drift was encountered at depths between 20 and 40 feet below mean sea level. Also, some minor sand lenses were encountered within the till as noted in test wells 4, 5 and 7. G. Discussion From reviewing the cross-sections, some underlying facts can be deduced. The majority of the island's topographic highs (the North Hill/West Harbor area, the Chocomont area and East Harbor areas) consist primarily of till with minor amounts of proximal outwash sands. Much greater amounts of proximal outwash sands are encountered in the southwestern part of the island (see MW-12 and 13) forming a possible aquifer. The proximal outwash sands also could provide aquifer materials in the vicinity of East Harbor (see MW-S) but the lateral and vertical extent of these deposits is much more confined. The major aquifer materials on Fisher's Island are the gravels associated with the marginal outwash and lacustrine deposits which underlie a majority of the island. The relationships between the till and the outwash are complex and remain equivocal. Two till events are suggested: An older till was encountered below the marginal outwash in the area east of Barlow Pond. A younger till was - 24 - - -,-----7".'=:~:--~7- I I I I I I I I I I I I I I I I I I I encountered mantling the marginal outwash and proximal outwash sands on the western end of the island. with marginal outwash encountered at depth in test holes drilled on the east end of the island, till in this area may represent the younger till. Aquifer materials tapped in the marginal outwash and lacustrine materials (MW-11, MW-6 and MW-1) should be considered as vertically and laterally confined. These gravels were deposited in association with large fluxes of meltwater directly into a meltwater lake at the glaciers edge. These fluxes waned during cold periods allowing finer materials such as clay/silt rhythms to settle out. Also, the axis of the meltwater fluxes migrated significantly in much the same ways that rivers migrate causing abundant lateral pinchouts of the gravels within the silts and clays. These processes created deposits which are discontinuous and very heterogeneous. This geologic origin must be considered when interpreting the volumes and yields of the ice contact stratified drift aquifers. Figure 7 shows the estimated distribution of facies. The marginal facies with thick gravels and silt is associated with two glacial stream discharge points in the central and western end of the island. The outwash channel mapped in the eastern end of the island by Upson (1971) and Goldsmith (1962) could be related to another discharge - 25 - I I I I I I I I I I I I I I I I I I l' GLACIER \ \ \ \ \ II I I \ \ \ - 26 - ------------------- TABLE 1 GENERALIZED STRATIGRAPHY Thickness Aqe (ft.) Interpretation Holocene 0-20+ Beach Deposits Pliestocene 100- 200= Proximal Outwash Marginal Outwash sand channels '" ...., Marginal Outwash: lacustrine deposits Non-stratified Ice Contact Drift (Glacial Till) 1 Crandall 1962 2 Upson 1971 3 Description Coarse sand and gravel marshy areas with sand, silt and or~anic matter. 1, Fine to medium sand with varying degrees of silt. possibl~ some gravel. Coarse to fine ~rey sand and gravel Grey silt and clay with varying rhythms degree~ of fine sand Poorly sorted sand, silt and clay wi varying djgrees of cobbles. Determined from on-site inspection or testing 4 Fuller 1904 Conductivity K or Water Bearing Properties (ft/dav) Probably water conductive but vertically shallow and latertlly confined K = 0.8 3 (from one well) K = 46 to 0.04 to K = 0.2 to 0.09 K = 0.1 to 0.007 ------------------- GENERALIZED STRATIGRAPHY (continued) Aqe Thickness (ft.) Interpretation Description Conductivity K or Water Bearing Properties Gardiners Clay Clay, fine sand and silt in guadational sub-units wjclays grading (possibly deformed) Low permeability possible con- fining unit.2 Cretaceous 100'I Unconsolidated Clastics stratified sands, ~~l~S and clays. Sands are probably permeable and water bearing but most likely saline. Low permeability porosity - However, fresh water was encountered at >300. 4 Pre-Cambrian Intrusive Granite No descript!ons available. 'oJ :.0 1 Crandall 1962 2 Upson 1971 3 Determined from on-site inspection or testing 4 Fuller 1904 I I I I I I I I I I - I I I I I I I I I point. Proximal outwash is thickest in the western end of the island where the island is widest. Glacial readvance and the affects of downwasting and ice tectonisms have greatly complicated this general scheme. Obviously more work is needed, specifically through the careful analysis of surface exposures to refine this model. - 29 - I I I I I I I I I I I I I I I I I I I III. HYDROGEOLOGY A. Introduction Pumping and periodic gauging of the monitoring wells was conducted to determine the hydrologic characteristics of the aquifers on Fisher's Island. This section describes the nature of ground water flow on the island and develops a rough ground water budget based on anticipated recharge and withdrawal. B. Hvdraulic Conductivities The ability of aquifer materials to transmit water is proportional to the material's hydraulic conductivity, (K) and hydraulic conductivity is proportional to the median grain size and degree of sorting of the material. Once the conductivity of the materials are known, estimates concerning aquifer yield and flow rates can be made. Conductivities were determined using the recovery test method which involves measuring the static water level in a well, pumping out a volume of water and monitoring the rate rise of the water in the well. Conductivity K, is given by K = r2 In (LjR), - 30 - I I I I I I I I I I I I I I I I I I I where r = radius of well R = radius of screen L = Length of screen Calculations are enclosed in Appendix B. A summary of the conductivity results for each well is given in Table 2. Hydraulic conductivity was also determined in the Middle Farms Aquifer using pump test data from the two public drinking water supply wells. Pumping data were analyzed using two separate methods and derived conductivity values ranging from 61 to 160 ft/day for the Proximal outwash gravel aquifer. Using these data, coupled with an understanding of the geology of the island, the vertical and lateral arrangements of aquifers can be roughly outlined. The term "aquifer" means a saturated unit which is capable of transmitting usable quantities of water. This is, of course, a relative term, but for this overview, an aquifer will be considered as a saturated material with conductivities greater than 1 ft/d. - 31- I I I I I I I I I I I I I I I I I I I TABLE 2 Hydraulic Conductivity Testing K Well # Screened Material (in ft/davl Test Date 2D sil t and Clay 0.094 5/88 3 Glacial Till 0.087 5/88 3 Glacial Till 0.26 7/88 4 Glacial Till 0.087 5/88 4 Glacial Till 0.10 7/88 5 Glacial Till 0.066 5/88 6 Sand and silt 0.14 5/88 6 Sand and silt 0.17 7/88 8 Glacial Till 0.088 5/88 9 silt 0.22 7/88 13 Sand 0.80 11/88 - 32 - I I I I I I I I I I I I I I I I I I I The geologic materials can now be evaluated as to their water bearing properties (conductivity ranges are tabulated next to geologic descriptions in Table 1 - Generalized Stratigraphy): 1. Beach Deoosits - these materials were not encountered during drilling but their well sorted, sandy nature suggests that they would be water conductive. However, their laterally limited extent and proximity to salt water suggests that they would not make productive aquifers. 2. Proximal Outwash Deoosits: - only one well was screened in the outwash deposits, GWI-12. The limiting factor with the outwash is the limited extent to which these deposits are saturated. The cross-sections show that most of the outwash exists above the average water table surface and this material, although porous, may not be available as an aquifer. This could be verified through additional well installations. J. Marainal Outwash Deoosits - this material contains abundant saturated coarse gravel deposits as noted by the high conductivities derived through the pump testing of the Middle Farms supply wells. The problem with this material is that it is complexly - JJ - I I I I I I I I I I I I I I I I I I I stratified with lacustrine clays. Coarse sands may be thick in places but may pinch out in others and stratify with fine grained silty clays. The laterally and vertically confined nature of this material may seriously restrict ground water yields. 4. Glacial Till - glacial till has generally lower conductivities because it is usually very poorly sorted and contains a high degree of silt/clay sized particles. Some minor water bearing lenses have been identified in some wells (see Well GWI-4A) but the significant lateral confinement of these zones precludes their use as major water supplies. Low volume homeowner wells may tap usable supplies of water from these deposits. C. Water Level Data Water level readings were determined for the wells on several occasions from 6/14/88 to 7/25/89. These readings were subtracted from surveyed well elevations to determine the water table elevations relative to mean sea level. These data, coupled with the elevations of surface water expression of the water table (ponds), allows for a determination of the ground water surface across the island. - 34 - I I TABLE 3 - WATER LEVEL DATA I WATER TABLE DATA DEPTH TO WATER I WEll DATE: ELEVATION 06/14/88 07/21/88 10/12/88 11/14/88 04/20/89 07/25/89 ============================================================================== I WEll: HW-l 15.33 9.80 10.50 NOT GAUGED 21.67 9.75 OESTROYED HW-1A 24.37 NO WEll NO WEll NO WEll 24.65 NOT GAUGED DESTROYED HW.2S 11.72 4.65 6.90 7.40 6.67 4.10 4.40 HW-2D 12.14 7.45 7.75 8.28 7.95 6.05 6.00 HW'3 19.14 11.30 12.90 14.15 13.90 10.35 10.52 HW.4 20.54 6.55 8.90 10.50 10.42 6.75 5.70 MW-4A 21.93 NO WEll NO WEll NO WEll 12.18 8.75 7.40 MW-5 15.40 10.70 11.90 12.25 12.07 10.15 10.10 MW-6 22.68 12.25 13.80 13.60 14.10 11.35 10.60 MW-7 67.01 DRY DRY DRY DRY DRY DRY MW-8 10.36 8.25 8.80 8.80 8.52 7.15 7.15 MW-9 17.75 13.40 13.30 14.10 14.34 12.20 DESTROYED MW-l0 9.25 NO WEll NO WEll NO WEll 7.10 6.15 6.25 MW-l1 21.97 NO WEll NO WEll NO WEll 18.15 16.00 14.80 MW-12 54.10 NO WEll NO WEll NO WEll 42.60 41.50 38.90 HW-13 17.93 NO WEll NO WEll NO WEll 10.53 8.35 8.90 MW-14 UNSURVEYED NO WEll NO WEll NO WEll NO WEll NO WEll 13_50 MW-15 UNSURVEYED NO WEll NO WEll NO WEll NO WEll NO WEll 22.60 MW-16 UNSURVEYED NO WEll NO WEll NO WEll DRY 21. 05 22.60 I I I I I WATER TABLE ELEVATION WEll ELEVATION 06/14/88 07/21/88 10/12/88 11/14/88 04/20/89 07/25/89 ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- MW-l 15.33 5.13 4.83 NOT GAUGED -6.34 5.58 DESTROYED MW-1A 24.37 NO WEll NO WEll NO WEll -0.28 NOT GAUGED DESTROYED MW-2S 12.14 5.37 4.82 4.32 5.05 7.32 7.32 MW-2D 11. 72 5.59 4.39 3.87 4.19 6.09 6.14 MW-3 19.14 8.34 6.24 4.99 5.24 8.79 8.62 MW-4 21. 93 12.99 11.64 10.04 10.12 13.79 14.84 MW-4A 20_54 NO WEll NO WEll NO WEll 9.75 13_18 14.53 MW-5 15.40 4.20 3.50 3.15 3.33 5.25 5.30 MW-6 22.68 10.33 8.88 9.08 8.58 11.33 12.08 MW-7 67.01 DRY DRY DRY DRY DRY DRY MW-8 10.36 2.01 1.56 1.56 1.84 3.21 3.21 MW-9 17.75 4.85 4.45 3.65 3.41 5.55 DESTROYED MW.10 9.25 NO \JEll NO \JElL NO WEll 2.15 3.10 3.00 MW-ll 21.97 NO WEll NO WEll NO WEll 3.82 5.97 7.17 MW-12 54.10 NO WEll NO WEll NO WEll 11.50 12.60 15.20 MW-13 17.93 NO WEll NO WEll NO WEll 7.40 9.58 9.03 MW-14 UNSURVEYED NO WEll NO WEll NO WEll NO WEll NO WEll . MW.15 UNSURVEYED NO WEll NO WEll NO WEll NO UEll NO WEll . MW.16 UNSURVEYED NO WEll NO WEll NO WEll . . . MEAN 6.53 5.57 5.08 5.87 7.85 8.87 I I I I I I I I I - 35 - ~ I I I I I I I I I I I I I I I I I I I The water elevation data is compiled in Table 3. The mean water table surface averaged between 6 and 9 feet above sea level for the period of measurement with a low water level at 5.08 AMSL during October of 1988 and a high water level of 8.87 feet on 7/25/89. Water level readings from 11/14/88 at MW-1 and MW-1A show effects of pumping from the Middle Farms Aquifer and these readings do not represent static conditions. Water table values for 4/20/89 are plotted on Plate III to show the orientation of the water table during an intermediate water level position. The highest water level elevations are located in the central parts of the island specifically MW-12 and MW-4. The highest water elevations can be found just north of Isabella beach where pond elevations reach up to 24.5 feet above mean sea level as shown in large scale topographic maps provided by the Suffolk County. It is debatable as to whether these ponds represent the true water surface or a perched water table; perched water tables are saturated materials that are separated from the major or regional water table by unsaturated materials. It is likely that the thick lacustrine clays underlie these surface water bodies, preventing water infiltration. Drillers log available for a homeowner's well (the Gaston's well) near these ponds record over fifty feet of clay with occasional fine to coarse sand lenses. - 36 - I I I I I I I I I I I I I I I I I I I The water table intersected at MW-16, Chocomont East, may also represent a perched water condition. This well was dry when first gauged in November of 1988. However, the following two rounds encountered over seven feet of water. This increase is over twice as great as any other water level increase noticed in this time period. MW-16 is screened in relatively impermeable till and water level fluctuations are probably caused by the low hydraulic conductivity of the impermeable layers. D. Ground Water Flow Ground water elevation contour lines on Plate III roughly define four ground water mounds with each mound sharing common discharge areas. Ground water flow is oriented perpendicular to contour lines, radiating in all directions away from ground water highs or recharge areas towards the discharge area which ultimately would be the Long Island or Block Island Sound. The western flow mound has a primary recharge area somewhere between monitor well 6 and monitor well 12 with a maximum water table elevation of approximately 12 feet above MSL. Some constriction of this flow cell is noted between Goose Island and Hay Harbor and it may be possible to define a fifth flow mound within the northeastern end of the island. - 37 - I I I I I I I I I I I I I I I I I I I A second mound parallels Isabella beach with highest ground water levels occurring in the clay pit ponds adjacent to Isabella Beach and in Brickyard and Barlow Ponds. The northern extent of this mound is not known but an additional flow mound may be located in the hummocky terrain located between West Harbor and Chocomont Cove. Ground water flow is skewed somewhat to the north with the axis of the flow mound paralleling Isabella Beach. The Middle Farms aquifer area is a discharge point between the mound just described and a large mound recharging at Middle Farms Pond and the highlands around the Chocomont Reservoir. Not much detail can be defined in this ground water mound because of the sparsity of monitoring data. The eastern most mound can be defined east of East Harbor with recharge occurring at the high points defined south of Ice Pond. Ground water elevations and ground water flow are not well defined. Monitor well 8 is located between the Chocomont and East Harbor mounds. vertical flow has been described by two well pairs, MW-2S and MW-2D, MW-4A and 4. Both pairs show a head loss with depth indicating a downward vertical flow. This condition is to be expected in areas with high infiltration and little runoff. However, it should be noted that - 38 - I I I I I I I I I I I I I I I I I I I stratification of coarse and fine sediments typical of the proximal outwash are bound to create confined water tables that would show localized areas of upward vertical flow. E. Ground Water Recharae Recharge on Fisher's Island comes exclusively from direct precipitation on the island and of this precipitation, significant amounts of water are lost to runoff, evaporation and transpiration (uptake by vegetation). Values for precipitation were determined from data collected by the Water Works at Barlow Pond and estimates for runoff, evaporation and transpiration are based on data from similar areas in this region. 1. precioitation - average rainfall on Fisher's Island is tabulated below (from Fisher Island Water Works). Average annual rainfall on the island is approximately 53 inches per year. Average rainfall is higher than the mean annual rainfall noted on Long Island or Plum Island. Proximity to the mainland and exposure to mainland generated thunderstorms may cause this greater precipitation on Fishers Island compared to the other nearby islands. Probable precipitation data from drought and periods of excessive rainfall are also tabulated on Table - 39 - -.- - - - - - - - - - - - - - - - - - - - TABLE 4 - AVERAGE PRECIPITATION FISHERS ISLAND PRECIPITATION DATA AVERAGE MONTHLY AND YEARLY RAINFAll JAN FEB MARCN APRIL MAY JUNE JULY AUGUST SEPT OCT NOV DEC 1970 2.20 5.65 4.15 3.10 3.45 1.95 3.12 2.22 4.21 6.1B 3.40 1971 2.79 5.18 2.93 2.32 4.42 0.54 3.41 1.75 1.25 4.73 6.37 6.00 1972 2.21 5.48 6.05 5.87 4.22 9.25 1.83 1.90 3.93 4.70 8.93 8.47 1973 3.30 3.14 4.12 7.31 4.90 2.51 6.25 3.66 2.55 3.40 2.40 7.95 1974 4.27 2.39 4.99 3.45 2.80 2.70 1.53 2.21 4.99 2.70 1.30 7.33 1975 7.87 4.90 3.69 4.50 3.20 5.57 4.09 4.38 6.68 7.78 6.81 5.44 1976 6.11 2.95 3.42 1.68 3.03 1.50 2.95 8.09 2.21 6.12 0.47 3.09 1977 3.55 2.57 6.22 4.97 2.93 5.00 1.68 6.50 6.02 9.19 5.73 6.19 1978 7.72 1.00 3.33 1.94 7.91 0.79 5.93 7.75 4.60 2.20 3.73 7.51 1979 13.39 6.02 3.10 5.52 7.60 2.60 1.92 6.35 4.71 5.71 4.85 2.71 1980 1.96 0.70 10.10 6.25 2.63 2.55 3.21 3.34 0.97 5.77 4.72 1.47 1981 0.43 6.24 0.20 5.59 1.73 7.88 4.50 1.80 4.60 4.20 3.10 6.60 1982 4.55 4.00 5.10 4.80 2.70 17.40 2.20 3.70 3.90 4.10 5.10 2.60 1983 5.62 4.60 9.25 12.20 5.60 3.10 2.30 6.30 1.40 6.00 11.70 6.50 1984 2.00 8.30 6.40 6.10 8.50 9.60 9.50 0.10 2.30 4.50 3.30 3.60 1985 1. 10 2.10 4.00 0.50 7.00 7.30 2.80 9.80 3.50 3.30 9.20 1.80 1986 5.78 4.50 3.80 2.60 1.10 4.80 5.70 4.90 1.20 3.75 8.30 11.90 1987 5.75 0.75 7.00 7.60 2.35 0.68 1.50 4.45 5.15 3.09 3.00 3.00 Average 4.61 3.72 4.96 4.85 4.21 4.85 3.51 4.45 3.45 4.75 5.29 5.31 ... C> PRECIPITATION DATA FROM OTHER NEARBY STATIONS GROTON FROM 1951-80, ORIENT FROM 1941-50, GREENSPORT FROM 1941-50 JAN FEB MARCH APR MAY JUNE JULY AUG SEPT OCT NOV DEC ANNUAL GROTON 4.41 3.96 4.76 4.17 3.84 2.69 3.20 4.01 3.95 3.93 4.62 5.01 48.55 GREENPORT 2.80 2.03 3.06 2.89 3.20 2.09 2.51 3.72 1.78 2.17 3.90 3.23 33.38 ORIENT 3.52 2.75 3.60 3.08 3.54 2.09 2.46 3.84 2.06 2.19 4.59 3.58 37.30 PROBA8lE PRECIPITATION AT GROTON STATION DURING DROUGHT JAN FE8 MAR APR MAY 90X 1.70 2.17 2.87 1.94 1.54 10X 8.47 6.01 7.57 7.30 6.63 (90X) AND JUN 1.16 5.06 FLOOD (lOX) PERIODS (FROM HUNTER AND MEADE, JUl AUG SEPT OCT NOV 1.35 1.39 1.46 1.90 1.99 6.10 9.76 8.23 7.35 6.92 1983)' DEC 2.13 8.68 ANNUAL 38.10 60.05 'EACH PRECIPITATION VALUE IS THE AMOUNT OF PRECIPITATION THAT Will 8E EQUALED OR EXCEEDED BY A CERTAIN PERCENTAGE OF EVENTS PROBABLE PRECIPITATION FOR FISHER'S ISLAND DURING FLOOD AND DROUGHT PERIODS" JAN FEB MAR APR MAY JUN JUl AUG 90X 1.75 2.01 2.98 2.23 1.68 2.08 1.47 1.51 10X 8.85 5.61 7.89 8.49 7.07 9.12 5.16 6.71 SEPT 1.46 5.04 OCT 1.88 8.93 NOV 1.98 7.88 DEC 2.10 11.15 ANNUAL 41.58 65.57 I I I I I I I I I I I I I I I I I I I 4. Drought and above normal precipitation statistics were calculated for Groton, Connecticut by Hunter and Meade, (1983). The Groton precipitation data is obtained from the Groton-New London Airport, located approximately 3 miles north of Fishers Island. Drought period rainfall values are exceeded 90% of the time while wet period rainfall values are exceeded only 10% of the time. The differences between these extremes and the average Groton values are extrapolated to the Fisher's Island data to estimate above and below normal precipitation frequency and magnitude. Based on these data, drought years occurring every lout of 10 years will have approximately 41 inches of annual precipitation, while wet years (wettest year out of 10) have as much as 65 inches. 2. Runoff - Values of runoff have not been measured or calculated for the island and estimates are here derived from Hoffman for Northfork, Southhold (1959) and Crandall for Plum Island (1962). Hoffman uses 10% as a runoff figure since most of the rainfall is expected to infiltrate through the silty loam soil on Southhold. Plum Island, like much of Fishers Island, is covered by a relatively impermeable till and displays considerably steeper topography relative to North Fork, Southhold. These factors lead Crandall to suggest runoff of around 15% of mean annual precipitation on Plum Island. Therefore, the same percentage is thought to be applicable to Fishers Island. - 41 - I I I I I I I I I I I I I I I I I I I 3. Evapotranspiration - Potential ground water recharge is also lost not only to runoff, but also to evaporation and to transpiration by plants. Hoffman estimates that evaporation ranges from 12 to 17 inches per year and transpiration is approximately 9 inches. Crandall (1962) notes that the transpiration noted on North Fork may be higher than Plum Island because of extensive cultivation on the former. This elevated rate of transpiration on the North Fork is balanced against an interpreted higher evaporation rate on Plum Island because of the large bodies of ponded water on the island. Plum Island is similar to Fishers Island in that there is very little cultivation (with the exception of lawn watering) and an abundance of fresh water ponds. Therefore, Crandall's (1962) estimate of 21 to 26 inches per year evapotranspiration rate is used in the Fishers Island water budget calculation. 4. Recharqe Rate - The total area of the island is 4.25 square miles, but many of the thinner parts of the island and areas close to the shorelines probably do not provide significant recharge to the island's aquifers. Recharge occurs primarily in the center of the flow mounds defined on Plate 3. Areas on the outside of these flow mounds that discharge into the Sound probably provide very little water by way of recharge to the island's aquifers. For recharge calculations, the recharge areas for the island are defined by the 5 foot contour line on Plate 3. Ground - 42 - I I I I I I I I I I I I I I I I I I I water below this contour begins to show signs of quality degradation and pumping in this area can quickly cause sea water intrusion problems. Using the five foot contour line describes two separate recharge zones: a large zone incorporating the western, Isabella/Barlow Pond, and Chocomont Flow Mounds and a much smaller, separate zone for the eastern flow mound. The area of these recharge zones was determined by planimetry with the larger western recharge area at 1.95 square miles and the smaller eastern recharge area at 0.202 square miles. Totalling these two areas produces a sum of 2.15 square miles for the island or roughly 1/2 the total island area. This matches Crandall's (1962) determination of recharge area for Plum Island which was taken as 50% of the total island area. subtracting runoff and evapotranspiration from the total average precipitation yields an annual recharge of roughly 19 inches per year. Totalling this across the effective recharge area yields a volume of 93,000,000 cubic feet per year or 709 million gallons per year. These recharge rates match interpreted rates on North Fork and Southhold fairly well (see Table 5). - 43 - I I I I I I I I I I I I I I I I I I I Plum Island West Orient, LI Area 1.3 miles2 2.3 Miles2 Fishers Island 4.25 miles TABLE 5 RECHARGE RATES Estimated Annual Recharqe 164 million gals. Annual Recharqe Rate 126 million qals. square mile 350 million gals. 152 million qals. square mile 709 million gals. 167 million qals. square mile - 44 - I I I I I I I I I I I I I I I I I I I Using extrapolations from the Groton Precipitation data, recharge for very wet and drought years, ranges from a low of 79 million gallons per square mile and 251 million gallons per square mile, respectively. These estimates assume that evapotranspiration and runoff remain constant. F. Salt/Fresh Water Interface The quantity of fresh water stored on Fisher's Island is primarily dependent on the depth to salt water. Fresh water occupies a relatively thin lens overlying salt water throughout the island. For isotropic and heterogeneous aquifers (ideal conditions) the depth to salt water is described by the Ghyben-Herzberg equation: h = t where g-l h = depth of water below sea level t = height of fresh water above sea level g = specific gravity of sea water, taken as 1.025 Using this equation, one foot of fresh water elevation or head above sea level equates to a fresh water lens approximately 40 ft. thick. Water level data from monitoring wells show that the depth to salt water or the salt/fresh water interface varies from greater than 600 feet below sea level inland to less than 80 feet near the shoreline. Water elevation readings can be used to determine the depth of the salt/fresh water interface, because each foot of elevation, multiplied by 40, approximates the depth to the salt/fresh interface. - 45 - I I I I I I I I I I I I I I I I I I I This relationship does not necessarily apply within heterogeneous aquifers and geologic analysis has shown that all aquifer materials on Fisher's Island are essentially heterogeneous. Heath (1970) notes that crossing from conductive to relatively non-conductive boundaries produces losses in head which reduce the thickness of the fresh water lens. Therefore, estimates of depth to the salt/fresh water interface derived from the Gyben-Herzberg relationship must be viewed as maximum depths of fresh water on Fishers Island. G. Water Use Information on total water use is based on data from the Fisher's Island Water Works and on estimates of water use and irrigation from private wells. 1. Water Works: The status of the current Water Works was defined in a report by Buck and Buck in January of 1988. Records in that report show that annual water production varied from between 54 to 67 million gallons. The projected annual demand is anticipated to be 87 million gallons by the year 2010. The report does not include withdrawals from private wells but notes that the number of private wells on the island has risen and most of these wells are used for irrigation. Another disturbing trend recognized by Buck and Buck is the increasing use of large automated irrigation systems for large lawns. - 46 - I I I I I I I I I I I I I I I I I I I 2. Private water use: Hoffman (1959) estimates 100 gallon/per day/per capita domestic water use. Using population records, domestic water usage would be 73 million gallons to 95 million gallons in the year 2010. This seems to match the magnitude of withdrawals expected by the water company. 3. Irriaation: the amount of water used for watering lawns is difficult to determine using the limited amount of available data. The estimates presented here must be viewed only as estimates and starting points for further work. A generally accepted rate of water use for vegetative growth is one inch per week. Taking the growing or landscaping season to be 18 weeks results in 18 inches of required precipitation plus irrigation. 50% of this water is estimated to come from precipitation requiring the remainder to come from ground water via irrigation. The area of application on the island has not been determined but is estimated to be 10 to 20% of the total land area or approximately 0.84 square miles. Nine (9) inches of water over 0.84 square miles yields an estimate of 131 million gallons per year. Over 80% of this water is probably lost to evapotranspiration leading to a net annual loss of approximately 100 million gallons. However, a study on Long Island by Hauptmann, et al., 1989 - 47 - I I I I I I I I I I I I I I I I I I I has determined that water use by lawn sprinkling during the summer months is about ten times normal residential use. For Fisher's Island this would mean that over 300 million aallons could be potentiallv lost annual Iv throuah lawn irriaation. Total water usage is tabulated against derived recharge calculations for very wet flood and drought years in Table 6. Using irrigation maximums of 300 million gallons/year, maximum annual water usage is estimated at 373 million gallons/year and this water usage is expected to rise to 395 million gallons per year by 2010. Using the water budget derived in previous sections, the recharge rate varies from 336 million gallons per year during drought years to 1,083 million gallons per year during wet years. Comparing these figures quickly shows that water demand can outweigh recharge during drought years and water demand can make up approximately 50% of average annual recharge. When comparing these figures it is important to remember that the island's coarse aquifer deposits are laterally discontinuous and irregular and whether or not 50% of the annual recharge can actually be withdrawn from these aquifer materials must remain a point of debate and concern. In conclusion, these data show that ground water is limited in three ways: 1. the quantity of precipitation and resulting recharge to the ground water supply; 2. the - 48 - I I I I I I I I I I I I I I I I I I I ability of the glacial sediments to yield water and 3. the position of freshwater/salt water interface. All three factors have to be considered on Fisher's Island when making water supply and usage decisions. TABLE 6 - WATER BUDGET * WATER RECHARGE P90 E.2Q PIO Precipitation 41" 53" 65" Runoff 15% (6") 15% (8") 15% (lO") Evapotranspiration 26" 26" 26" Recharge Rate 336 mgy 709 mgy 1,083 mgy Recharge Rate/sq mi 79.1 mgy 167 may 251 mgy Todav 2010 WATER USAGE Water Works 60 mgy 90 mgy Domestic Use 73 mgy 95 mgy IRRIGATION 100 mgy - 300 mgy MAXIMUM POSSIBLE USE 373 mgy 394 P90 = drought conditions; annual rainfall exceeded 90% of the time P50 = average rainfall P10 = very wet conditions; annual rainfall exceeded 10% of the time. * refer to text for derivation of these figures. (1) Based on recharge area of 2.15 mi2 - 49 - I I I I I I I I I I I I I I I I I I I IV. CHEMICAL ANALYSIS AND WATER OUALITY PROBLEMS A. Introduction Ground water samples were obtained from monitoring wells to assess ground water quality. Water samples were taken in cooperation with the NY DEC following protocols for ground water monitoring. Each sampling event involved well gauging and purging of three well volumes to replace any stagnant water with formation water. Well purging was accomplished with either a hand pump or electric pump. Water samples were obtained with cleaned and rinsed stainless steel bailers. Water samples were analyzed in the field for temperature, pH, and specific conductivity by members of the DEC. Water samples were taken from each well were analyzed at DEC labs for metals, inorganics, herbicides, pesticides and volatile organic compounds. Data sheets for these analyses are included in Appendix C. Results from these analyses are used to make conclusions concerning ground water quality across the island. Water quality data was also obtained from homeowner wells to help identify water quality trends. All data are tabulated in a ground water quality summary Table 7. Ground water quality across the island is summarized on Plate IV. Ground water analyses are plotted on a modified stiff diagram for each sample point which allows a rapid overview of ground water quality. For monitor wells, the last sampling event is - 50 - I I I I I I I I I I I I I I I I I I I TABLE 7 - GROUND WATER CONTAMINANT SUMMARY --------------.-......-----------------------------------------------.---------------------------------------- 06/13/88 06/13/88 11/14/88 06/14/88 11/14/88 06/14/88 PARAMETERS MIl-I MW-2S MW-2S M11-2D MII.2D MW.3 -------------------------------------------------------------------------------------------------------------- METALS (mg/L): CALCIUM 3.10 2.00 3.90 20.00 31.00 6.50 IRON 0.90 0.50 1.20 1.00 9.00 3.80 MAGNESIUM 1.70 1.10 2.00 9.00 15.00 2.60 MANGANESE 0.14 0.15 0.22 0.61 1.40 0.36 POTASSIUM 1.80 0.90 1.70 3.60 6.80 2.00 SOl) IUM 7.80 6.60 10.00 22.00 29.00 17.00 INORGANICS (mg/L): AMMONIA-N NO<0.02 NO<0.02 NO<O.02 NO<0.02 0.08 (0.03) 0.03 CHLORIDE 14.00 16.00 12.00 76.00 91.0 (92.0) 30.00 NITRATE-N 0.16 NO<0.05 ND<0.05 NO<0.05 ND<0.05 (ND<0.05) NO<0.05 NITRITE 0.01 0.00 0.00 0.003 0.001 (0.003) 0.00 PNOSPHATE NT NT ND<0.005 NT ND<0.005 NT SULfATE 6.40 7.00 6.40 4.90 1.4 (1.4) 14.00 flELO MEASUREMENTS: TEMPERATURE (C) 15 14.00 16.00 14.00 14.00 14.00 pH 6.3 5.70 6.20 6.80 6.70 6.20 SPECifiC CONDUCTIVITY (ur/los) 80 76.00 105.00 338.00 222.00 146.00 SDWA HERBICIDES (ppb): 2,4-D ND<1 NT NT NT NT NT 2,4,5-TP NO<1 NT NT NT NT NT PESTICIDES (ppb): ALDICARB ND<1 ND<l NT NO<l NT ND<l ALDICARB SULfOXIDE ND<l NO<l NT NO<1 NT ND<l ALDICARB SULfONE ND<l NO<l NT ND<1 NT NO<l CARBOfURAN ND<l ND<l NT ND<l NT ND<l 3'HYDROXYCARBOfURAN ND<1 ND<1 NT ND<1 NT ND<l OXAMYL ND<1 ND<1 NT ND<1 NT ND<l CARBARYL ND<1 ND<1 NT ND<1 NT NO<l l-NAPHTHOL NO<l ND<l NT NO<l NT ND<l METHOMYL NO<l ND<l NT NO<l NT ND<l VOLATILE ORGANICS (ppb): CHLOROfORM ND<0.5 ND<O.S NO<O.5 ND<0.5 NO<O.S ND<D.5 METHYLENE CHLORIDE ND<O.S ND<D.5 NO<O.S ND<0.5 ND<0.5 ND<0.5 1,1,1 TRICHLOROETHANE ND<0.5 ND<O.5 ND<0.5 ND<O.5 ND<0.5 NO<O.S CIS OICHlOROETHYlENE ND<O.5 ND<O.5 ND<D.5 ND<D.5 ND<O.5 ND<O.5 BENZENE ND<0.5 ND<O.5 NO<D.5 ND<0.5 NO<0.5 NO<O.5 TOLUENE NO<0.5 ND<O.S ND<0.5 2.00 1.00 2.00 ETHYLBENZENE NO<0.5 NO<O.S NO<O.S 1.00 1.00 ND<O.S TOTAL XYLENES NO<O.S 2.00 3.00 9.00 11.00 2.00 1,2,4 TRIHETHYLBENZENE NO<O.S NO<O.S 0.60 S.OO 1.00 1.00 p.OIETHYLBENZENE ND<O.S NO<O.S ND<O.S 2.00 ND<O.S 1.00 1,2,4,S TETRAMETHYLBENZENE NO<O.S ND<O.S ND<O.S 2.00 ND<O.S ND<O.S ISOPROPYLTOLUENE (P-CYMENE) ND<O.S ND<O.5 ND<O.5 NO<O.5 ND<O.5 ND<O.5 -------------.----.......-........---.-------.-------------------------_.._-----_.._-------.----_._----------- NOTE: NO - Not detected < detection limit. ppb - parts per bill ion. mg/l - milligrams/liter. NT - Not Tested - 51 - I I TABLE 7 CONT'O .-.-.----...---------------------------------------------.-------------------------------------------------------------------- I 11/16/88 06/15/88 11/15/88 11/16/88 06/14/88 11/16/88 06/15/88 11/15/88 RAMETERS M~'3 M~'4 M~'4 M~-4A M~'5 M~.5 M~'6 M~'6 _._____________________.________________._.________________w________________________________________________-------------___ METALS (mg/L): ELCIUM RON GNESIUH MANGANESE fTASSIUH OOIUM INORGANICS (mg/L): _HMONIA-N MLORIOE ITRATE-N NITRITE PHOSPHATE fuLFATE ~ELO MEASUREMENTS: TEMPERATURE (C) IIJ:ECIFIC CONOUCTIVITY (umhos) SO~A HERBICIOES (ppb): I:~:~-TP PESTICIDES (ppb): ILO I CARB LOICARB SULFOXIDE LOICARB SULFONE CARBOFURAN .'HYOROXYCARBOFURAN XAMYL ARBARYL I-NAPHTHOL METHQMYL ~LATILE ORGANICS (ppb): CHLOROFORM NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 METHYLENE CHLORIDE NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 _.1.1 TRICHLOROETHANE NO<0.5 NO<0.5 NO<0.5 NO<O.5 NO<0.5 NO<0.5 1.00 0.70 IS DICHLOROETHYlENE ~D<O.5 ND<O.5 NQ<O.5 NO<O.5 ND<O.5 ND<O.5 NO<O.S NO<O.5 ENZENE ND<O.5 ND<O.5 NO<O.5 0.70 ND<O.5 ND<O.5 2.00 ND<O.5 TOLUENE 4.00 NO<0.5 1.00 NO<0.5 4.00 2.00 2.00 1.00 ITHYLBENZENE 1.00 NO<0.5 NO<0.5 NO<0.5 3.00 1.00 NO<0.5 NO<0.5 OTAL XYLENES 16.00 2.00 2.00 NO<0.5 19.00 11.00 3.00 1.00 ,2.4 TRIMETHYLBEN2ENE 7.00 1.00 1.00 NO<0.5 3.00 4.00 NO<0.5 NO<0.5 p'OIETHYLBENZENE 2.00 NO<O.~ 1.00 NO<0.5 0.80 1.00 NO<0.5 NO<0.5 1.2.4,5 TETRAHETHYLBENZENE NO<0.5 0.80 NO<0.5 ND<0.5 0.90 NO<0.5 NO<0.5 NO<0.5 SOPROPYLTOLUENE (P-CYMENE) NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 2.00 NO<0.5 NO<0.5 ____OP__O_______________._._________________________________0_______._._______________________________________~~~~_________. NOTE; NO - Not detected < detect;on limit. ppb - perts per billion. ov/L - .illigrons/liter. NT - Not Tested I I I I 9.90 12.00 5.00 0.80 4.00 21.00 0.13 28.00 0.14 0.09 0.14 7.50 14.00 6.60 81.00 NT NT NT NT NT NT NT NT NT NT NT 6.50 0.60 2.80 0.25 2.30 14.00 51.00 25.00 4.60 3.80 17.00 19.00 0.02 0.14 (0.13) 22.00 18.00 NO<0.05 0.05 0.01 0.05 NT 0.19 13.00 12.00 14.00 6.40 118.00 NT NT NO<l NO<l NO<l NO<l NO<l NO<l NO<l NO<l NO<l 14.00 7.40 71.00 NT NT NT NT NT NT NT NT NT NT NT 7.6IJ 4.6IJ 2.00 0.33 4.40 40.00 0.92 18.00 0.08 0.03 0.100 9.80 13.00 7.40 125.00 NT NT ND<1 NO<l NO<l NO<l NO<l NO<l NO<1 NO<l ND<1 - 52 - 14.00 1.50 5.00 0.50 2.80 15.00 0.03 25.00 NO<0.05 0.00 NT 2.60 17.00 7.00 158.00 NT NT NO<l NO<l NO<l NO<l NO<l NO<l NO<l NO<l NO<l 30.00 28.00 13.00 2.50 13.00 14.00 0.13 20.00 NO<0.05 0.03 0.05 0.80 16.00 8.70 115.00 NT NT NT NT NT NT NT NT NT NT NT 12.00 1.40 4.30 0.16 3.00 35.00 0.10 27.00 0.48 0.143 NT 37.00 14.00 6.50 240.00 NO<l NO<l NO<' NO<' NO<l NO<l NO<l NO<l NO<l NO<l NO<l 28.00 26.00 11.00 1.60 13.00 38.00 0.07 23.00 0.37 0.11 0.12 33.00 14.00 6.50 140.00 NT NT NT NT NT NT N1 NT NT NT NT I TABLE 7 CONT'O I .....__...~.._____________..___..._____....._________.____.pe.______________________________________________--------------------- I 06/13/88 11/14/88 06113188 11/14/88 11/16/88 7125189 11/15/88 7125189 AMETERS M11-8 M11-8 MW-9 M11-9 MII-l0 MII-l0 MW-l1 I"J-11 __________________________________.________________________________________________.____________________________0._------------ METALS (mg/l): flClUM RON GNESlUM MANGANESE fTASSIUM 00 lUM INORGANICS (mg/L): ~HMONIA-N NLORIOE ITRATE-N NITRI TE PNOSPHATE IUlFATE ElD MEASUREMENTS: TEMPERATURE (C) II~ECIFIC CONDUCTIVITY (umhos) SDWA HER81CIDES (ppb): I:~:~-TP PESTICIDES (ppb): ILOICARB LDICARB SULFOXIDE LDICARB SULFONE CARBOFURAN i-HYDROXYCARBOFURAN XAMYl ARBARYL I-NAPHTHOL METHQHYL ILATILE ORGANICS (ppb): CHLOROFORM ND<0.5 ND<0.5 ND<0.5 ND<0.5 ND<0.5 METHYLENE CHLORIDE ND<0.5 ND<0.5 ND<0.5 ND<0.5 ND<0.5 _,1,1 TRICHLOROETHANE ND<0.5 ND<0.5 ND<0.5 ND<0.5 ND<D.5 IS DICHlOROETHYLENE ND<O.5 NO<O.5 NO<O.5 NO<O.5 NO<O.5 ENZENE ND<0.5 ND<0.5 ND<0.5 ND<0.5 ND<0.5 TDLUENE 3.00 3.00 I.DO 1.00 ND<0.5 ITHYlBENZENE ND<0.5 2.00 ND<0.5 1.00 ND<0.5 DTAl XYLENES 4.00 24.00 2.00 10.00 ND<0.5 ,2,4 TRIMETHYLBENZENE 4.00 5.00 2.00 3.00 ND<0.5 p-DIETHYLBENZENE 2.00 2.00 2.00 2.00 ND<0.5 1#2,4,5 TETRAHETHYlBENZENE NO<O.5 NO<O.5 NO<O.5 ND<O.5 ND<O.5 SOPROPYlTOLUENE (P-CYMENE) ND<0.5 ND<0.5 NO<0.5 ND<0.5 ND<0.5 --______0______---------_.------------------------.---____0__________________________.____._ NOTE: NO - Not detected < detection limit. ppb - parts per billi on. mg/L - milligrams/liter. NT - Not Tested 1.80 1.20 2.10 0.28 .2.80 110.00 0.03 82.00 1.20 0.81 NT 87.00 14.00 7.00 575.00 ND<1 ND<1 ND<1 ND<1 ND<1 ND<1 ND<1 ND<1 NO<1 ND<1 NO<1 I I I I 11.00 24.00 12.00 4.7D 9.00 120.00 12 4.8 5.5 0.43 4.5 16 37.00 28.00 28.00 4.80 17.00 42.00 7.50 0.50 2.80 0.25 1.90 13.00 0.12 83.00 0.18 0.22 0.21 61.00 0.02 22.00 0.51 0.02 NT 9.30 NOT TEST EO DUE TO COLLOIDAL SUSPENSION 0.07 17.00 0.05 (0.05) 0.03 0.030 6.20 18.00 7.40 474.00 15.00 6.50 128.00 14.00 6.80 118.00 14.00 7.10 65.00 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NO<1 ND<1 ND<1 ND<1 NO<1 ND<1 ND<1 ND<1 NO<1 ND<1 ND<1 NO<1 ND<1 ND<1 ND<1 ND<1 ND<1 NO<1 NT NT NT NT NT NT NT NT NT - 53 - 6.50 0.04 3.70 <.02 1.30 14.0 <.02 28.0 0.36 0.001 NT 10.0 18.00 4.80 6.80 1.90 4.70 41.00 0.23 25.00 0.99 0.04 0.03 43.00 13.00 5.90 134.0D ND<1 ND<1 ND<1 ND<1 ND<1 ND<1 ND<1 NO<1 NO<1 3.00 ND<O.S NO<O.S ND<0.5 0.70 0.60 NO<O.5 NO<O.5 ND<0.5 ND<0.5 ND<O.5 NO<0.5 15.0 4.8 5.8 0.49 3.70 27.00 0.39 2S.00 1.50 C.029 NT 21.00 NT ;.90 ,~6.0 NT NT NT NT NT NT NT NT NT NT NT NT NT N:<0.5 w:"o.s ~:<O.5 N:<O.5 0.7 N!:<0.5 N:..:;O.5 2.00 2.0 1.0 0.7 w:..:;O.S I I TABLE 7 CONT'D ....---------------------------------------------------------------------------------------- JIl~~:~:~~____________.._________.::~~~~___~~~~!~__..::~~~!;---~~~~~--~~~~!;--~~~~~!~ METALS (mg/L): ILCIUH ON GNESIUM MANGANESE FASSIUH IUM INORGANICS (mg/L): IMONIA'N LORloE TRATE'N NITRITE fOSPHATE LFATE FIELO MEASUREMENTS: TEMPERATURE (C) ~ECIFIC CONDUCTIVITY PESTICIOES (ppb): 10leARB oleARB SULFOXIDE olCARB SULFONE CARBOFURAN IHYOROXYCARBOFURAN AMYL RBARYL I-NAPHTHOL (T HOHYL ATllE ORGANICS (ppb): CNLOROFORM No<0.5 No<0.5 No<0.5 No<0.5 1.00 No<0.5 'THYLENE CHLORIDE No<0.5 No<0.5 1.00 No<0.5 NO<0.5 No<0.5 ,1,1 TRICHLOROETHANE NO<0.5 NO<0.5 NO<0.5 NO<0.5 0.90 NO<0.5 15 DICHlOROETHYlENE ND<O.5 ND<D.5 0.80 NO<D.5 ND<O.5 ND<D.5 BENZENE 8.00 NO<0.5 0.80 4.00 No<0.5 3.00 TOLUENE 0.70 NO<0.5 1.00 1.00 NO<0.5 NO<0.5 ~HYLBENZENE NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 NO<0.5 TAL XYLENES No<0.5 2.00 NO<0.5 1.00 NT NT ,2,4 TRIMETHYLBENZENE NO<0.5 1.00 NO<0.5 NO<O.5 NO<0.5 NO<O.5 p,oIETHYLBENZENE NO<0.5 0.70 NO<0.5 7.00 NO<0.5 NO<0.5 1,2,4,5 TETRAHETHYLBENZENE NO<0.5 0.05 NO<0.5 2.00 NO<0.5 No<0.5 SQPROPYLTOLUENE (P-CYMENE) NO<0.5 ND<0.5 No<0.5 NO<0.5 NO<0.5 No<0.5 .-.----------------------------------------.----------------------------------------------- NOTE: NO - Not detected < detection limit. I ppb - parts per billion. mg/l - .illigrams/liter. NT - Not Tested 6.60 5.10 3.0 0.40 .3.40 12.00 0.11 9.90 0.98 0.02 0.04 13.00 (...mos) 13.00 7.10 54.00 SO~A HERBICIDES (ppb): 14,0 4,5-TP NO<l ND<l ND<l ND<l ND<l ND<l NO<l ND<l NO<l I I I 6.80 0.31 2.70 0.08 1.90 12.0 0.05 16.0 1.BO 0.017 NT 9.50 NT 6.90 69.0 NT NT NT NT NT NT NT NT NT NT NT NT NT 10.00 21.00 6.70 15.00 11.00 44.00 0.07 55.00 No<0.05 0.00 0.01 61.00 13.00 6.50 281.0 ND<l NO<1 NO<l ND<l ND<l ND<l NO<1 NO<l ND<l 23.0 0.26 14.0 3.50 3.80 50.0 0.03 31.0 0.70 0.021 NT 51.0 NT 6.50 412.0 NT NT 23.0 10.0 9.60 1.50 3.40 22.0 0.03 30.0 1.00 0.068 NT 11.0 NT NT NT NT NT NT NT NT NT NT NT -54 - 2.80 0.06 1.10 0.06 1.00 8.20 0.03 14.0 NO<0.5 0.005 NT 6.70 NT NT NT NT 5.80 58.0 NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT NT I I I I I I I I I I I I I I I I I I I plotted. Other sampling locations such as homeowner wells and monitoring wells from other projects are also included. B. General Ground Water Composition As noted in the hydrogeology section, ground water recharge comes exclusively from rainfall and is eventually discharged into the sea. Accordingly, the major ion chemistry of ground water varies from the composition of rain water close to the recharge areas to sea water close to the areas of discharge. To determine how ground water chemistry varies from place to place across the island, ground water samples were plotted on Piper diagrams along with water samples from Barlow and Middle Farms Pond and samples of precipitation and sea water. Data for precipitation and sea water are taken from Thomas et al., 1968. In preparing piper diagrams raw data for anions (chloride, sulfate and bicarbonate) and cations (calcium, magnesium, sodium and potassium) are first reduced to milliequivalents per liter. These values are totalled and % meqjl are calculated for each anion and cation for each ground water sample. This information is then transferred to the Piper diagram. Samples from each flow mound are grouped together on a single Piper diagram to help identify chemical trends in the flow mound. - 55 - I I I I I I I I I I I I I I I I I I I 1. Precipitation: Data concerning precipitation was taken from the Noank area (Thomas et aI, 1968). These authors show that precipitation is affected by industry in the Thames River area. When air flow is from west, the industrial influence is seen in low pH readings between 3.9 and 4.5 and relatively high sulfate readings. However, when air flow is from the ocean (from the south) pH readings are higher, around 6, and bicarbonate levels are increased over sulfate levels. precipitation on Fisher's Island most likely shows a more continuous oceanic influence over the Noank data with data somewhere between oceanic and westerly air mass data from Noank. 2. Sea Water: Sea water data from Hem (1959) show that sea water differs from precipitation primarily in percentages of chloride and sulfate; sea water is higher in chloride while precipitation is higher in sulfate. Percentages of cations between precipitation and sea water do not vary significantly and reflect changes in air mass flow direction rather than inherent differences. 3. Ground Water: trends in ground water flow are most dramatically shown by differences in pH. Mean pH for the island is 6.7. Water samples from wells located in the center of the recharge area from wells are significantly below this value while discharge area wells (such as well 8) are above this value. pH changes with respect to depth also - 56 - I I I I I I I I · MIDDLE FARMS POND o BARLOW POND Ha ~ HANCOCK E - EVANS I Z = ZANGETTI NUMBERS. "\ MONITOR WELLS I 0 HI pH > 6.7 .. O (no'~ymbol represents an Intermediate pH) LO pH < 6.7 I ... PRECIPITATION +SEA WATER cJ' ":Jo~"/ o \~ '< Ca :> CATIONS CI ANIONS EXPLANTION !GroundWater, InC. FISHER'S ISLAND PIPER DIAGRAM MOUND 1 WE.STERN GROUND WATER MOUND FLOW I I I I I I I I I I I I I 0- ",0'11-"'/ Oti ~~ \!?)@ 09~ @ ill ~ o ~@ < Ca CATIONS > CI ANIONS EXPLANATION . MIDDLE FARMS POND o BARLOW ROND C - CALHOUN H - HALL NUMBERS = MONITOR WELLS o HI pH > 6.7 O (no symbol represents an Intermediate pH) LO pH < 6.7 ... PRECIPITATION +SEA WATER !GroundWater, InC. I FISHER'S ISLAND PIPER DIAGRAM" MOUND 2 ISABELLA BEACH/BARLOW POND GROuND WATER MOUND FLOW 0- ,,0'\1.""/ o S I I I I I I I I I I I I ..: Ca CATIONS EXPLANATION · MIDDLE FARMS POND o BARLOW POND NUMBERS = MONITOR WELLS OHI pH <"6.7 O (no symbol represents an Intermediate pH) LO pH > 6.7 . PRECIPITATION + SEA WATER o \~ @ [!] 1/ O~I / (j 5 ~ @ S ;> CI ANIONS i\GroundWater,lne. FISHER'S ISLAND PIPER DIAGRAM MOUND 3 MIDDLE FARMS/CHOc:oMONT GROUND WATER MOUND FLOW I I I I I I I I I I I I I I I I I I I as shown in the well pairs 2S, 2D and 4, 4A. In each case, the deeper well is higher in pH indicating that the deeper ground waters are closer to the salt or brackish water interface zone and are zones of ground water discharge. An increase in sodium and chloride and a decrease in calcium with increased flow is typical of most ground water flow systems (Freeze and Cherry, 1979). This basic trend can help further delineate discharge and recharge areas. Piper diagrams for each flow mound shows a general enrichment in sodium, potassium and chloride. within each flow mound, wells located near discharge areas and at the borders of the mounds are characterized by sodium, chloride enrichment zones. Generally, low pH wells near recharge areas have major ion chemistries that cluster very close to percentages shown in Middle Farms and Barlow Pond. High pH wells plot further away from the pond plots suggesting further travel within the ground water system. Further travel does not automatically mean increased chloride and sodium concentrations. Intermediate ion chemistries are sometimes displayed showing enrichment in sulfate (see wells MW-2 and MW-14 in Mound 1 and MW-4A, MW-2S and MW-5 in Mound 2). Sulfate enrichment is sporadic due to the uneven distribution of sulfur related compounds such as anhydrite or gypsum in the soil. Discharge areas are defined by high pH wells with either high chloride (Well 2D in Mound 2 or) high sodium (Well 4A in Mound 2 and Well 8 in Mound 3). - 60 - I I I I I I I I I I I I I I I I I I I C. Areas of Dearaded Qualitv Water quality as assessed by the wells is generally excellent across the island. However, several threats to water quality have been identified including: 1) salt water intrusion; 2) elevated levels of iron and manganese; and 3) trace hydrocarbon contamination. 1. Salt water intrusion: As noted in the hydrogeology section, the fresh water lens is relatively thin. Ground water contamination by salt water is most easily identified by high levels of chloride but sodium, calcium, magnesium and specific conductivity levels may also be influenced. Chloride levels naturally range between 5 and 25 ppm and levels above 25 ppm may be related to salt water intrusion. Concentrations above 250 to 300 ppm give water a salty taste and concentrations above 500 ppm make water unusable for most purposes. Salt water can be introduced into the fresh water lens either through upconing or through lateral encroachment. Upconing is the drawing of salt water from directly under a pumping well. Lateral encroachment is the lateral movement of salty water into the fresh water lens along highly conductive deposits. Given that the geology of the island is highly heterogeneous, it is more likely that salt water intrusion/contamination will arise from lateral encroachment rather than from upconing. - 61 - I I I I I I I I I I I I I I I I I I I Several areas of concern have been identified. Information from the Fisher's Island Country Club on the eastern end of the island identified a salt water contamination problem in association with the pumping of water for golf course irrigation. During the pumping of the production well in association with this irrigation system, an increase in chloride content was noted and chloride levels reached 169 ppm after 24 hours of pumping. Monitoring well 8 located on the Country Club Golf Course detected over 80 ppm chloride during two sample rounds indicating that salt water intrusion is a very real problem on the east end of the island. Elevated levels of chloride were also detected in MW-2D located in the Middle Farms area. Salt water may migrate along in a more permeable layer at depth extending into the Middle Farms aquifer area. Several other smaller areas of salt water contamination are visible on the map including MW-13 and the Evans well. Both of these wells are located relatively close to sea water on the island's edge. These data suggest that future ground water pumping, particularly heavy pumping such as for irrigation or centralized water production, could create additional salt water problems. Pumping of ground water should be - 62 - I I I I I I I I I I I I I I I I I I I carefully monitored to insure that drawdowns are maintained above MSL. Drawdowns to MSL or below may cause eventual upconing of salt water and salt water contamination of the aquifer. If ground water quality is degraded by pumping, the pumping rate should be decreased to resist or reverse further intrusion. Thomas, et al. (1968) gives several case studies involving reversibility from salt water contamination. Norwich Hospital (Connecticut) noted an increase of 6 ppm chloride to 695 ppm chloride after an increased pump rate from 500 gpm to 1000 gpm. When the chloride concentrations were noticed, pumping was halted for a period of about a year. During this period, the natural ground water gradients were re-established and salt water was flushed out of the aquifer. Pumping was then resumed at 500 gpm and intrusion problems were not encountered. A similar case was noted for Dow Chemical (Ledyard, CT) in 1968 when pumping caused salt water intrusion from a nearby estuary. After reducing the pumping rate, withdrawals continued without a problem. Thomas, et al. (1968) concluded that stratified drift is generally permeable enough so that intrusion can be reversed if a satisfactory hydraulic gradient is re-established. Salt water contamination from hurricane storm surge and spray may cause longer term contamination of the aquifer. Crandall (1962) suggests that increases in chloride content from supply wells may have resulted from - 63 - I I I I I I I I I I I I I I I I I I I hurricanes in 1954 and 1955, and elevated chloride levels continued until 1959. This contamination is more persistent than salt water encroachment or intrusion problems because chlorides were introduced at the well source and the entire aquifer had to be flushed out before normal chloride concentrations could be obtained. Supply wells at Middle Farms are approximately 10 feet above MSL and wash and spray from a major hurricane could significantly affect the ground water quality for an extended period. 2. Recharqe from ponds: The ponds on Fisher's Island serve as an important reservoir for stored fresh water with Barlow Pond being presently used as the island's water supply source. Also, the ponds serve as important recharge areas for ground water. Plum Island and Northfork do not have as many ponds per unit area which may be one reason for the decreased thickness of their fresh water lenses in comparison to Fisher's Island. However, storage and recharge in fresh water ponds may produce some undesirable effects on ground water quality. None of these ponds have any source of recharge other than precipitation and this may lead to decreased oxygen content, increased manganese and iron content and bacteria counts. a. Iron and Manqanese: Plate IV shows that many of the elevated iron concentrations (in excess of 20 ppm iron) are noted downgradient from fresh water ponds. - 64 - I I I I I I I I I I I I I I I I I I I This connection of increased iron and manganese content and ground water recharge through organic rich sediments has also been noted by Silvey and Johnson (1977) in wells from Rhode Island. Suffolk County Health Department has a health standard of 0.3 ppm for drinking water supplies but they note that iron is a common problem and more than half of the wells in Suffolk County would be above this limit if they were all tested. This standard of 0.3 ppm is mostly based on aesthetic qualities such as taste and iron staining of clothing, cookware and glassware. However, increased iron content may result in precipitation of iron in piping and pumps, shortening their life spans, causing substantial and increasing supply costs and problems. Therefore, while iron is more of an inconvenience with homeowner wells, pump burn-out on a public supply well could be a major problem. b. Bacteria: Very limited bacterial sampling from the Island Pond and neighboring wetlands area showed some elevated levels of fecal coliform and fecal streptocci. Much of this fecal material may be related to bird life on the island rather than septic contamination but this has not been determined. In one case, bacteria from adjacent wetlands migrated through a coarse gravel zone and were detected in a homeowner well. This shows that where soil conditions are not sufficient for bacteria removal, - 65 - I I I I I I I I I I I I I I I I I I I ponds and swamps can serve as sources of bacterial contamination of ground water. Unfortunately, not enough data is available from the monitoring wells to address widespread trends in bacterial levels on the island. 3. Landfills and Orqanic Contaminants: Considering the finite nature of the water supply on the island, all man-induced pollution should be precluded or minimized. The impact of two dump areas, the Pickett Landfill and the Airport Metal dump are addressed in this study. A third disposal area, the wood and brush dump, located near the airport, was not studied. Pickett's landfill, located on the south side of the island, east of the military reserve, currently accepts garbage, trash and sept age from the island's population. MW-13 was placed in a location thought to be downgradient of the landfill area to identify leachate discharged from the landfill on ground waters. Landfill leachate typically contains high levels of nitrogen, iron, manganese, chlorides, oxygen demanding organics, alkalinity and possibly volatile organic compounds from industrial, commercial, or domestically used fuels or solvents. A second dump (known as the Metal Dump) is located on the west side of the island just east of the airport. The dump developed in an old army bunker that was used for the disposal of 55-gallon drums, electrical - 66 - I I I I I I I I I I I I I I I I I I I transformers, oil tanks and other materials according to the fire department. MW-10 was installed to assess this contamination. Both of the monitoring wells, 13 and 10, encountered high concentrations of iron and chlorides and it is uncertain whether these contaminants are related to the landfill or to natural occurrences. Nitrate and ammonia concentrations, at levels likely due to landfill leachate, were not encountered at elevated concentrations. However, low levels of volatile organic compounds have been detected at MW-13 possibly related to disposal of chemicals at pickett's landfill. Unfortunately, conclusions regarding the status of these two dump sites must remain equivocal. Much additional study is needed to assess these dump areas in more detail to adequately determine the presence, extent and degree of ground water degradation originating from these sources. MW-lO and MW-13 may simply be located outside of leachate plumes. Further study would expand the monitoring network in the vicinity of the dumps to answer site specific questions such as local gradients, flow directions and contaminant plume identification. 4. Other sources of contamination: More widespread sources of contamination may include septic - 67 - I I I I I I I I I I I I I I I I I I I fields, improper and/or widespread use of fertilizers and pesticides, underground storage tanks and improper chemical use and disposal. The ground water analyses produced no data suggesting that septic fields or fertilizers/pesticides are a widespread problem. However, trace levels of a variety of volatile organic substances were detected in some of the monitoring wells. Volatile organics discovered in the wells installed by S. B. Church (MW-1-9) have been attributed to grease used on the well casing threads. All well casings have been removed to remove any unnecessary "noise" from future sampling rounds. Trace levels were also encountered in wells installed by C. Welti and two separate rounds of water sampling produced problematical results. Different contaminants were detected in the same well during different sample rounds and concentrations increased and decreased between the two rounds depending on the well. The exact origin of detected hydrocarbons is unknown. Volatile organics have been detected before on the island in monitoring wells installed ~s part of the proposed trash incinerator. Levels of less than 10 ppb total volatile organics were encountered, generally matching the levels of organics detected in the wells tested as part of this study. - 68 - I I I I I I I I I I I I I I I I I I I V. CONCLUSIONS 1. Three geologic materials have been defined in the shallow subsurface of Fisher's Island: 1. Glacial till consisting of poorly sorted sand, silt and clay with abundant cobbles; 2. Marginal outwash consisting of coarse gravel to cobble lenses in a finer grained silt to clay matrix accumulating directly adjacent to the recessional moraine; and 3. Proximal outwash consisting of coarse to medium moderately sorted sand deposited from braided streams some distance from moraine margins. 2. The gravels associated with the proximal outwash and the distill outwash sands form the most accessible and viable aquifers with relatively high conductivity values ranging from 1 to 100 ft/day. Highest conductivities were observed in the proximal gravels but the yield from these gravels is highly unpredictable because of their variable extent. Proximal outwash sands may present more reliable yields because of their more extensive continuity. Only one proximal outwash sand aquifer was encountered (in MW-12) and its characteristics are not well defined. 3. Ground water flow is defined by at least four ground water mounds cells on the island. Two other flow mounds are possible but are not currently well defined. Ground water flows from recharge areas located in the center - 69 - I I I I I I I I I I I I I I I I I I I of the mounds to discharge areas located at the mound borders. Ponds serve as the major recharge areas and ground water discharges to the sea and shared cell boundaries. Average annual ground water recharge is estimated as 167 million gallons per square mile. 4. Recharge to the aquifers is provided solely by precipitation and recharge averages 709 million gallons annually, island-wide. Estimates of drought precipitation produce aquifer recharge rates at 336 million gallons annually. Considering that water usage on the island is estimated at 373 million gallons (largely depending on the amount of irrigation) and considering the irregular geometries of the aquifer materials, periods of ground water mining will occur during years with below normal precipitation. This may lead to salt water intrusion through lateral migration, up-coning or both. 5. Salt water intrusion has been identified in the eastern flow mound due to pumping of irrigation water for the country club golf course. Aquifer materials are primarily composed of till and salt water has encroached laterally along slightly more permeable lenses. Several other places on the island, including deeper zones in the Middle Farms aquifer, show evidence of salt water intrusion. Effects of salt water intrusion can be retarded by reducing or - 70 - .'>>-: I I I I I I I I I I I I I I I I I I I curtailing pumping until chloride concentrations can be flushed out of the aquifer materials by recharging fresh water. 6. Iron and manganese appear to be persistent and common problems in the ground water because of recharge through oxygen depleted swamps and ponds. 7. Ground water degradation from dump sources on the Island (Pickett's Landfill and the Metal Dump) was not conclusively shown. Volatiles detected in Monitor well 13 (near the pickett Landfill) may be related to fuels or chemicals disposed of at the landfill. It is highly suspected that contaminant plumes exist at both sites. - 71 - I I I I I I I I I I I I I I I I I I I v. RECOMMENDATIONS The conclusions from this study show that the shallow ground water resources on Fisher's Island can provide a finite and limited supply of fresh water to the island's population. Over-use combined with drought conditions will likely result in depletion of the fresh water aquifer and potentially serious salt water intrusion effects. Therefore, it is imperative that proper management programs be instituted as soon as possible. Ground water management should focus on two major goals: 1. the collection and assessment of additional ground water information required to adequately describe ground water quality and quantity; 2) the establishment of island wide policies and/or regulations to promote ground water protection and encourage conservation. A. Additional Assessment: Information collected up to this point in time suggests that the aquifers on Fisher's Island are relatively complicated and restricted. Efforts should be made to refine estimates of aquifer yield and location. Also, contamination sources identified in this study should be properly assessed. The following steps are recommended: 1. The monitoring network around the Middle Farms aquifer should be expanded to include several additional wells. These wells should be placed to replace destroyed - 72 - I I I I I I I I I I I I I I I I I I I monitoring wells (MW-9), and supplement the current network of monitor wells and to further delineate the lateral extent of the gravel. Once these wells have been installed, a program of water level measurement and conductivity monitoring should be instituted so that the influences of pumping can be monitored. Monitoring and assessment should be conducted monthly from May to September and twice during the winter months. 2. All the other monitoring wells installed as part of this study should be gauged and sampled on a quarterly basis. Ground water level data should be correlated with precipitation data so that hydrologic trends in recharge can be identified. Well sampling for basic ground water constituents plus nitrate and a Flame Ionization Detection (FID) screen for organic constituents should be sufficient to detect ground water quality trends. Steps one and two are combined on a proposed ground water monitoring schedule (Table 7). 3. Additional assessment is required to identify . and delineate the extent and degree of possible ground water contamination at Picketts Landfill and at the metal dump. At least three additional monitoring wells should be installed at each site so that a more detailed view of ground water flow, geology and contamination can be determined. If no contamination is detected at the metal - 73 - ------------------- TABLE 8 - PROPOSED GROUND WATER MONITORING SCHEDULE MONITOR WELLS 2S 2D 3 4 5 6 8 9* 10** 11 12 13** 14 15 16 ============================================================================================= WATER LEVEL*** M M Q Q Q Q Q A Q Q Q Q Q Q Q CONDUCTIVITY*** M M Q Q 8 Q Q A Q Q Q 8 Q Q 8 SODIUM Q Q Q Q Q Q Q Q Q Q Q Q POTASSIUM 8 Q Q Q Q Q Q 8 Q Q Q 8 8 Q 8 CALCIUM Q Q Q Q Q Q Q Q Q Q MAGNESIUM Q 8 Q Q Q 8 Q Q 8 Q 8 Q 8 Q 8 IRON Q Q Q Q Q Q Q Q Q MANGANESE Q 8 Q 8 Q 8 8 Q 8 Q Q 8 8 8 8 CHLORIDE Q Q Q Q Q Q BICARBONATE Q Q Q Q Q 8 8 Q Q 8 Q Q 8 8 Q SULFATE Q Q Q Q Q Q Q Q Q ~ FID SCREEN A A A A A A A A A A A A A A pH*** M M Q Q Q Q Q M Q Q Q Q Q Q Q ..... * WELL 9 IS DESTROYED - RE~UIRES REPLACEMENT - OTHER MONITOR WELLS NEEDED ... ** PICKETTS LANDFILL AND ME AL DUMP - OTHER MONITOR WELLS REQUIRED TO ASSESS LEACHATE ***PARAMETER ASSESSED IN THE FIELD M= MONTHLY DURING SUMMER TWICE IN THE WINTER Q= QUARTERLY - FOUR TIMES A YEAR A= ANNUALLY I I I I I I I I I I I I I I I I I I I dump, monitoring for this site can be discontinued. However, ground water monitoring at Picketts landfill should be continued so that landfill leachate can be characterized and controlled. This monitoring should be considered standard procedure accompanying landfilling of solid wastes. 4. An additional source of ground water should be sought. The present information suggest that the North Hill area contains good aquifer materials. The installation of 2 more monitoring wells with appropriate water quality and pump testing is suggested to further assess the water supply potential and water quality character of this aquifer. The proximal outwash underlying the Hay Harbor golf course may also provide additional supplies, and additional monitoring will be required to assess the feasibility of a public water supply in this area. The hydrogeology of the area between East Harbor and Chocomont Cove is relatively unknown and the potential for water supplies in this ground water mound have not been fully addressed. An additional monitoring well in this vicinity would be helpful. B. Management Policies In addition to additional assessment work, island wide policies and/or regulations should be established as a part of an island-wide ground water protection plan. The - 75 - I I I I I I I I I I I I I I I I I I I goal of this plan and these policies is to draw attention to the limited nature of ground water resources inspiring conservation efforts and to develop and enforce land-use policies that will preserve the ground water resources. The following essential steps should be taken: 1. The withdrawal rate, frequency and purpose for all existing private wells should be determined through an island-wide survey. A major conclusion of this study is that aquifer materials are relatively thin and discontinuous. Given this geometry, the identification and development of additional aquifers capable of providing a centralized source of water for the entire island may not be successful. Therefore, the continued use of private wells is necessary. If properly managed, they may balance ground water withdrawals across the island preventing significant localized aquifer depletion. Therefore, care should be taken in locating and utilizing these private wells. 2. The proper governing body (probably the Town of Southold), should adopt regulations requiring each new building and/or well permit to provide the following information: a. a map with a scale and north arrow showing the location of the well in relation to nearby structures and roads; - 76 - I I I I I I I I I I I I I I I I I I I b. a geologic log showing all strata changes and the location of pump intake; c. well yield and drawdown based upon an 8-hour pump test; d. the location of any nearby wells; e. the projected withdrawal rate based on proposed water use (domestic use, irrigation, swimming pools, etc.). If the projected withdrawal rate is to be greater than 5,000 gallons per day, a more detailed study should be conducted to determine the wells zone of contribution. The method outlined by Kerfoot and Horsley (1988) may be appropriate for this purpose (refer to Appendix for the methodology). 3. Regulations concerning periodic inspection and testing of private supplies should be adopted. This would provide safeguards over public health that are routinely conducted on larger public supplies. Regulations should include an annual inspection of the well to assure that the casing is intact, the cap is tight and no subsidence has taken place around the well. Secondly, a water sample should be taken annually for potability analysis including pH, - 77 - I I I I I I I I I I I I I I I I I I I Alkalinity, Hardness, Chloride, Color, Odor, Turbidity, Nitrates, Nitrites, Ammonia, Detergents, Iron, Total Coliform, Manganese and Sodium. Optional testing for pesticides should also be made available for residences close to golf courses. This testing will not only protect public health but will also provide useful information on regional water quality trends. 4. The Town of Southold may consider adopting special regulatory controls in the two most sensitive areas on the island: the watershed area tributary to Barlow and Middle Farms Ponds and within the island's delineated recharge areas especially Middle Farms. Suggested actions are: 1. Zonina Considerations a. Overlay Aquifer Recharge Protection districts and Watershed Areas; b. Prohibition of Selected Land Uses; c. Special Permitting (could be used to regulate lawn care activities in a. above, such as fertilizer use, pesticide use and irrigation); - 78 - I I I I I I I I I I I I I I I I I I I d. Large Lot Zoning or re-zoning; e. Transfer of Development Rights (to the Town or FIDCO, for example, in especially sensitive areas); f. Growth Controls (either a moratorium or limitation on numbers of building permits issued in a specified time period, to allow for better planning of anticipated growth). 2. Additional Health Requlations a. Underground Fuel storage * prohibit new residential underground fuel storage tanks; * remove existing residential underground fuel storage tanks; * prohibit all new underground tank installations (except for replacements) within aquifer recharge or watershed areas. b. Develop a Phosphorous Buffer Zone around fresh water lakes and ponds, particularly water supply sources. A 300 foot setback for septic systems is recommended. - 79 - I I I I I I I I I I I I I I I I I I I c. Ban all Septic Tank Cleaning Agents (those containing synthetic organic chemicals) - this law is in place in Connecticut and on Cape Cod. d. Require mandatory septic system maintenance. An important issue related to this is the proper disposal of septic tank pumpings. The current practice of disposal at the Pickett Landfill is unacceptable. A permanent, appropriate disposal alternative is needed, either on or off Fishers Island. e. Develop a systematic and periodic septic system inspection program. This can also be a condition of a property sale or issuance of a building permit to expand or change an existing structure. 3. Non-Requlatorv Protective Measures a. Donations of land to the Town or local land trusts; b. outright purchase of lands in sensitive water resource areas; c. Conservation easements, or the voluntary relinquishment of certain development rights on the land. - 80 - I I I I I I I I I I I I I I I I I I I d. Public education of the critical nature of water supplies on Fishers Island; develop and carry out a specific public education program. e. Voluntary and involuntary water conservation measures such as: * 100% metering of all users on public water; * a pricing schedule designed to discourage large water consumption; additional revenues from increased rates should go toward more leak detection surveillance, repair and metering, as necessary, and public education. f. The Town and the Water Works should develop a Drought/Water Supply Emergency Plan and Procedures to deal with chronic and acute water supply shortages, to manage the island's limited resources in a water supply emergency. g. Amend building and plumbing codes to require the use of water saving devices on all new construction. Encourage the use and retrofitting of water saving devices through public education. h. The Town of Southold should fund and hire a full-time professional to oversee the implementation, - 81 - . I I I I I I I I I I I I I I I I I I I adoption and enforcement of the various regulatory tools needed to insure the on-going and future protection of water supplies on Fishers Island. i. Develop an official "Water Supply Watershed and Aquifer Recharge Areas" map for Fishers Island which can be used as a regulatory reference with respect to whatever controls are adopted. 5. All underground storage tanks, hazardous waste generators and septic field locations should be identified and inventoried. This may be the responsibility of the local health department through the use of mailed questionnaires followed by field checks. All information should be compiled on the Watershed/Recharge Area Map and held at a central location on the island. The success of this inventory hinges on a simple, clear form for inventory purposes and easy access to the information for decision-making purposes. - 82 - I I I I I I I I I I I I I I I I I I I REFERENCES Anderson, Mary P., 1989 Hydrogeologic facies models to delineate large scale special trends in glacial and glacial fluvial sediments: Geologic Society of America, Bulletin V. 101, P. 501-511. Brodzikowski, K., and van Loon, A. J., 1987. A systematic classification of glacial and periglacial environments, facies and deposits: Earth Science Reviews, V. 24 (5), p. 297-381. Crandell, H. C., 1962, Geology of Groundwater of Plum Island Suffolk County New York: Survey Water-Supply Paper 1539X. Resources Geological Edwards, M., 1986, Glacial Environments in Reading H.G. ed. Sedimentary Environments and Facies: Oxford, England, Blackwell Scientific Publishing, p. 445-470. Fleming, W. L. S., 1985, Glacial Geology of Central Long Island: Am. Jour. Sci. V. 30, p. 216-238 Flint, R. F., 1947, Glacial Geology and the Epoch: John Wiley and Sons, New York, 1971, Glacial and Quaternary Geology: and Sons, Inc. 892 p. Flint, R.F., 1971, Glacial and Quaternary Geology: John wiley and Sons, Inc.: New York, 589 p. Pleistocene 589 p. John Wiley Fraser, Gordon S., and Cobb, James C., 1982, Late Wisconsinan proglacial sedimentation along the West Chicago Moraine in Northeastern Illinois: Journal of Sedimentary Petrology Vol. S2, No.2 June 1982. Freeze, R. Allan, and Cherry, John A., 1979, Groundwater, Prentice Hall, Inc., Englewood Cliffs, New Jersey. Fuller, Myron L., 1904, Geology of Fishers Island, New York: Geologic Society of America Bull. Vol. 16, p. 367-390. GOldsmith, Richard, 1962, Surficial Geology of the New London Quadrangle, Connecticut-New York: U.S. Geological Survey, Washington, D. C. , 1982, Recessional Moraines and Ice Retreat in Southeastern Connecticut in Larson, G. J. and Stone, B. D. eds., Large Wisconsinan Glaciation of New England: Dubuque, Iowa, Kendall/Hunt Publishing Co. pg 61-76. Ground Water, Inc., 1989, Danbury, CT Watershed Protection Plan prepared for the Housatonic Valley Council of Elected Officials, Brookfield Center, CT. - 83 - I I I I I I I I I I I I I I I I I I I Hauptmann, M. G., van der Leeden, and Ross, L.C., 1989, Management of Regional Ground Water Issues: Town of Oyster Bay, Long Island in Recent Advances in Ground-Water Hydrology John E. Moore, Alexander A. Zaporozec, Sandor C. Lsallany, and Timothy C. Varney eds. American Institute of Hydrology, Minneapolis, Minnesota. Heath, Ralph C., 1971, Basic Ground-Water Hydrology: U.S. Geological Survey Water-Supply Paper 2220, Denver, CO. Hem, J. D., 1959, U.S. Geol. Survey - Water Supply paper, 1473, p. 10. Hoffman, John F., 1959, Hydrology of the shallow Ground-Water Reservoir of the Town of Southhold, Suffolk County, L.I., N.Y: U.S. Geological Survey open-file report. Hunter, Bruce W., and Meade, Daniel B., 1983, Precipitation in Connecticut, Department of Environmental Protection Bulletin No.6. Kay, Clifford A., 1960, Surficial Geology of the Kingston Quadrangle. Geological Survey Bulletin 1071-1. Kerfoot, William B., and Horsley, Scott W., Private Well Protection, 1988, Information Bulletin No. 10, Association for the Preservation of Cape Cod, Orleans, Mass. Rodgers, John, 1985, Bedrock Geological Map of Connecticut: Connecticut Geological and Natural History Survey and the U.S. Geological Survey. Silvey, W.D., and Johnson, H.E., 1977, Preliminary Study of Sources and Processes of Enrichment of Manganese in Water from University of Rhode Island supply wells: U.S. Geological Survey Open-File Report 77-561, 33 p. Thomas, Chester E., Jr., Cervione, Michael A., Jr. and Grossman, I.G., 1968, Water Resources Inventory of Connecticut Part 3 Lower Thames and Southeastern Coastal River Basins: Connecticut Water Resources Bulletin No. 15. Upson, Joseph E., 1971, Surficial Geological Map of the Mystic Quadrangle, Connecticut, New York and Rhode Island: U.S. Geological Survey 1970, The Gardiners Clay of Eastern Long Island: A Re-examination U.S. Geol.. Survey Prof. Paper 700-B p. 157-160. - 84 -