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HomeMy WebLinkAboutInvestigation of Water Resources June 1967 TOWN OF SOUTHOLD SUFFOLK COUNTY, LONG ISLAND,N.Y. INVESTIGATION OF WATER RESOURCES JUNE 1967 The preparation of this report w~s financially aided through a federal grant from the Department of Housing and Urban Development, under the Urban Planning Assistance Program for the Bureau of Planning Administration, New York State Office of Planning Coordination. It was financed in part by the State of New York. MALCOLM PIRNIE ENGINEERS. 226 Westchester Avenue White Plains~ N.Y. 10604 SECTION me II. III. IV. V. VI. VII. VIII. IX. NO. 1 2 5 6 7 TABLE OF CONTENTS INTRODUCTION GENERAL CONDITIONS WATER SYSTEMS AND WATER USE GEOLOGY HYDROLOGY AVAILABILITY OF FRESH WATER PROTECTION OF GROUND WATER F~ESOURCES FISHERS ISLAND WATER RESOURCES CONCLUSIONS AND RECOMMENDATIONS FIGURES Location Map Rainfall - Cutchogue 1949-66, incl. .~Typi~cal Geohydrological Section Water Table Contours Water Levels in Wells S6558 and S6780 ( Area A) - 1949-66, incl. Water Levels in Wells S65~2 and 'S652~ (Area B) 1949-66, incl. Water Levels in Wells S16787 ( Area D) and in S16783 (Area C) 1958-66, incl. · PAGES 1-6 7-14 15-22 23225 26-31 32-38 '39i45 46- 51 52-57 FOLLOWING PAGE~ ? 10 29 28 31 PLATE A B C D .PLATES Large Scale Map of Southold RepPoduction of Plate 1 of USGS-W.S. Paper 1619-GG - Surficial Geolggical Map of Southold Reproduction of Plate 3 - USGS-W.S. Paper 1619-GG - Map of Southold showing Location of Wells and Position of the Water Table in July 1959 Reproduction of Plate 2 of USGS-W.S. Paper 1619-GG - Geohydrologic Sections in Southold IN BACK COVER POCKET TOWN OF SOUTHOLD SUFFOLK COUNTY, LONG ISLAND, NEW YORK 1 INVESTIGATION OF WATER RESOURCES JUNE 1967 I. INTRODUCTION The preparation of this report for the New York State Office of Planning Coordination was financially aided through a Federal Grant from the Department of Housing and Urban De- velopment, under the Urban Planning Assistance Program f~r the Bureau of Planning Administration, New York State Office of Planning Coordination. It was financed in part by the State of New York, by the Town of Southold, and by the Village of Greenport. Purpose and Scope The principal purpose of this investigation and study was to provide information on the water resources of the Town of Southold in connection with the overall planning work under the Urban Planning Assistant Program for the Town. The following subjects were investigated and are dis- cussed in the report: (a) Available water resources and the quantity of water that may be obtained from the sources. (b) Past and present water usage in various parts of the Town. (c) Estimates of probable future water consumption and effects of land usage on available water resources. (d) Evaluation of various land use proposals, as re- lated to available water. (e) Consideration of methods for protecting and devel- oping the water resources of Southold~ as related ~ to plans for future development. The studies included field investigations of surface and underground conditions and a review and analysis of data ob- tained from previous investigations and reports. Information obtained during the investigations from records and operating experiences of the Greenport Water System and data obtained from representatives of the U. S. Geological Survey, the New York State Water Resources Commission, Suffolk County, the Town of Southold, and from others familiar with local condi- tions were yery helpful in connection with the studies. Field investigations included observations throughout the town related to agricultural,' residential, and business de- velopments and to public and private water supply and sewage disposal facilities. Visits were made during and after periods of heavy rainfall to observe the extent of surface ponding and run-off~ and during dry periods when there was maximum use of water for irrigation. The character of surface soils and underlying materials was investigated by sampling and observing samples of materials obtained from well drilling operations and from materials exposed in excavations. Relationship of Water Resources to PlanninK The sole source of water for the Town of Southold is ground water, replenished each year by a relati~ely small part of the rain which falls upon the area within the Town. A large portion of the available ground-water is used for irri- gation~ and the supply of ground-water that may be withdrawn safely is limited to less than twice the total amount that is used at the present time. For these reasons, the availability of water is a major factor in sound planning for the future development of Southold. In certain sections of Southold, much greater quantities of water can be withdrawn than from o'ther sections without contaminating the fresh water resources with salt water. 'This fact must be considered in connection with future planning. Previous Investigations and Reports There is a wealth of information available as to geolog-. ical, hydrological, and ground water conditions in Long Island, in Suffolk County an~ in'the Town of Southol~. Two of the most recent and most significant reports covering Southold ground-water conditions are the following: "Hydrology of the Shallow Ground-Water Reservoir of the Town of Southold, Suffolk County, Long Island, New York": New York State Water Resources Commission Bulletin GW-45 (Hoffman, J.F., 1961) "Geology and Ground-Water Resources of the Town of Southold, Suffolk County, New York": Geological Survey'Water-Supply Paper 1619 - GG (Crandell, H.C.) The two reports present results of investigations of the U. S. Geological Survey in cooperation with the Suffolk County Board of Supervisors, the Suffolk County Water Author- ity, and the New York State Water Resources Commission. They are part of an overall and continuing appraisal of ground water conditions on Long Island which was commenced by the Uo S. Geological Survey in 1932o Both of the above reports contain much information on existing wells, elevations of ground-water, and geological and hydrological data. They provide an excellent review of results of previous studies and reports. The plates in these two reports showing numbered well locations throughout the Town and contours and profiles showing elevations of ground water relative to mean sea level are of great value in con- nection with estimating the availability of fresh water in various parts of Southold. Some of these data are reproduced herein. The following recent reports also are of interest in connection with the water supply situation in the Town.of Southold: "Engineering Report on Water Supply - Village of Greenport - February 1964" - By Holzmacher, McLendon & Murrell. "Water Resources of the Town of Southampton, Suffolk County, New York - December 1966" -By Behre Dolbear & Company. "Pollution a~ Water Supply of the Town of Southampton - January 1967" - By John P. Mahoney, Consulting Engineers. The first of the above three reports contains mu~h in- formation concerning the property and operations of the water system of the Village of Greenport,'which serves water'to the Village and adjacent areas. The second and third are of inter- est because the water situation in the Town of Southampton, which comprises a large portion of the South Fork peninsula, in many respects is similar to the situation in Southold in the North Fork peninsula. ° Current Investigations and Stu~es The cooperative studies of U. S. Geological Survey and the New York State Water Resources Commission are continuing studies~ and additional data on underground water conditions and withdrawals throughout Long Island are collected each year. The Long Island District Office of Division of Water Resources of the New Y6rk State Cbnservation Department is at' 6 present conducting an interim water study of the Nassau- Suffolk region in connection with a long-range planning study, conducted by the New York State Office of Planning Coordination. Two additional interrelated investigations and studies are underway which will provide much information on ground- water resources in Suffolk County. One of these includes the construction of some 14 deep test wells, some of which will extend into bed rocks'. Two of the wells will be located in Southold along North Ro~d, one north of Cutchogue, and one northwest of the Village of Southold. This investigation is of particular interest, inas- much as very meager data exist on subsurface conditions in Southold below the existing irrigation and municipal wells, which are not very deep. The other investigation is a comprehensive water supply study for Suffolk County, financed by the State under its grant program for water supply planning. II. GENERAL CONDITIONS Location and Extent As shown on Figure l, the Town of Southold comprises the easterly 20-mile portion of the northerly peninsula, known as the North Fork, at the easterly end of Long Island. It also includes Robins Island in Peconic Bay and Gull, Plum, and Fishers Islands in Long Island Sound. The study area in- cluded in this investigation consists of the peninsular por- tion of the Town of Southold, which has an area of 42'.9 square miles and Fishers Island, which has an area of 4.2 square miles. Fishers Island is located about ll miles northeast from Orient Point and 7 miles southeast from New London. For convenience, the water situation in Fishers Island is discussed separately in Section VIII of this report. In the remainder of this report the mainland or p~ninsular portio~ of the Town will be referred to as "Southold,"and Fishers Island will be designated by name .... Geographical Features Southold is almost entirely surrounded by salt water. In general, the higher portions are adjacent to or near Long Island Sound and rise from 50 to 150 feet above sea level. The land slopes southerly for the most part toward Peconic, Southold, and Gardiners BayS. Southold has no surface streams or lakes CONNECTI CUT NEW YORK LONG NEW JERSEY QUEENS CO. KINGS * NASSAU ~.oN 6 CO. SUFFOLK CO. NEW soUND iSLAND TOWN OF SOUTHI isLAND , o~ oG~I~ ~ERS ISLAND GARDINtR$ 5 5 I0 15 20 SCALE IN MILES TOWN OF SOUTHOLD LOCATION MAP 8 of appreciable size, but there are a number of fresh water ponds~ some of which are a source of water for irrigation. Much of the land is open land, suitable for cultivation. There are a number of low wet areas and salt water marshes. Most of these are located adjacent to the numerous salt water inlets along the southerly shore of the peninsula. Three salt water inlets (Mattituck Creek, Hashamomack Pond, and Dam Pond) and adjscent'marshland~ and ~inlets'a~vide the'penin- sula into four separate island-iike hydrological areas. These areas, which are designated from west to east as Areas A, B, C, and D in Geological Survey Water Supply Paper 1619-GG, are considered separately in connection with estimating the potential yield of underground water, because areas for re- charge and ground-wate~ levels in each are different. There are two small peninsulas, Little Hog Neck and Great Hog Neck~ which extend southerly from the main 'Peninsula and are separated from it b~' sal~ water inlets and marsh~s. These also must be considered separately in connection with availability of ground-water. There are a number of attractive beaches along the souther- ly irregular shore line of Southold. These beaches and the fact that the area provides excellent natural facilities for boating and bathing, have resulted in the development of many areas along the south shore for seasonal and permanent homes. There are a few such developments along the northerly or Long Island shore line. However, 'the rugged nature of the~terrain and the fact that there are fewer favorable boat anchorages and attractive beaches has limited recreational developments along this shore line. Plate ~ in the pocket in the back cover of this report is a map of Southold upon which the developed areas of Southold are shown. The base map was prepared by Raymond and May, planning consultants for this project. This map.shows the limits of the'four hydrological areas A~ B, C, and D, and Little Hog Neck and Great Hog Neck, which are described above. Climate Southold has a mean annual temperature of about 50 degrees and an average rainfall of about 45 inches per year in the western and central portions, in accordance with long-term records at the Cutchogue Station. Shorter term records at Orient Point, East Marion~ and the Greenport Power House indi- cate that average yearly rainfall is about 10 per cent lower than at Cutchogue. Rainfall is generally heavy in the fall, winter, and spring months and much less during the summer months. Yearly rainfall records at the Cutchogue Station from 1949 to 1966, inclusive, are shown on Table 1. This shows that total rainfall at Cutchogue in 1965 was only 26.7 inches and that the average for 1963, 1964, and 1965 was only 31.7 inches. During these three years ~ record low rainfall was experienced in many parts of the.Northeast. TABLE 1 Annual Rainfall Records - Cutchogue Statioo 1949 - 1966~ Inclusive 'Year Rainfall In Inches 1949 45.21 1950 53.15 1951 60~50 1952 Record not complete 1953 51.18 1954 41.68 1955 35.15 1956 44.96 1957 33.46 1958 5t.47 1959 41.39 1960 38.12 1961 '41.38 1962 40.89 1963 33.16 1964 35.45 1965 26.68 1966 33.33 Figure 2 shows graphically rainfall at Cutch0gue Station by years and by months from 1949 to 1966, inclusive. Monthly and yearly rainfall records from 1960 to 1966, incl¼sive, at the Greenport Power Plant.and at the East Marion Well Field are shown on Table 70 FIGURE NO. 2 70 6O b.J 50 -r Z Z ~' 40 0 Z Z Z -r- I-- Z 0 $0 2O I0 0 I0.0 5.O 0 1950 1951 1952 195:5 1954 1955 1956 1958 1959 1960 1961 1962 1964 1965 60 5O 4O :5O 2O I0 0 I0.0 5.0 1967 1968 ll TABLE 2 RAINFALL RECORDS - GREENPORT AREA - 1960 - 1966, INCL. January February March April May June July August September October November December Total January February March April May June July August September October November December Total GREENPORT POWER HOUSE STATION 1960 1961 1962 1963 1964 1965 1966 3.87 1.70 4.50 3.12 4.61 1.18 3.34 5.56 3.14 3.45 3.06 3.65 2.67 3.87 1.96 3.95 2.56. 3.45 2.49 1.92 2.15 2.82 7,04 3.82 .47 6.54 3.36 1.36 2.58 ~.48 .83 3.85 1.31 2.01 6.31 2.05 1.49 3.25 4.35 1.77 1.93 1.67 5.25 2.28 1.45 2.68 3.~4 2.94 .96 .98 4.13 6.11 2.96 1.32 2.95 1.89 9.09 5.72 3.72 2.12 3.09 1.93 5.12 2.37 2.66 4.76 .14 4.99 2.03 3.07 3.09 3.01 5.67 6.40 2.64 1.37 3.71 3.67 3.14 1.89 2.74 5.46 1.56 3.18 43.29 42.74 42.01 35.34 41.81 25.85 36.63 EAST MARION WELL FIELD 1960 1961 1962 1963 1964 1965 1966 2.94 2.74 5.55 3.12 4.46 1.10 3.09° 5.90 3.83 3.45 3.06 3.58 2.74 3.46 1.75 4.22 2.56 3.45 2.57 1.28 2.21 2.70 8.25 3.64 .47 6.11 3.42 1.71 2.84 5.52 1.18 3.85 1.30 1.99 6.55 1.75 2.00 4.45 4.35 1.56 1.46 1.58 6.84 2.09 .62 2.68 4.29 2.37 .95 1.!0 4.10 5.42" 2.96 0.82 2.13 1.92 9.57 9.89 1.87 2.12 3.27 1.62 4.86 3.21 2.94 5.01 .13 5.10 2.05 3.28 3.20 3.46 5.33 5.84 2.71 1.41 3.70 3.94 2.92 1.90 2.46 5.37 1.02 3.16 45.74 51.96 40.98 34.49 41.14 22.59 36.47 Historical Development The development of Southold dates back to early in the 17th'century. It is believed that the first settlers were Englis~nen who came to Southold by way of New Haven. The early settlers cleared land and raised principally grain and forage crops. Since that time, agriculture has been an im- portant factor in the economy of Southold. Early in the 19th century, shipping and whaling were developed to a considerable extent. In 1848, the Long Island Railroad extension to Green- port was completed and the Village became the important mari- time center on a combined railroad and shipping route between New York and Boston. The Village at present continues to be a center.for commercial and recreational fishing activity. The main factor in the economy of Southold is agriculture, and this situtation probably will continue for many yeats. Topo- graphy, climate, and soil conditions are favorable for produc- t$on of vegetables. Conditions are particularly suitable for large scale potato growing and also, to a lesser degree, for raising such crops as cauliflower , cabbage, and B russel sprouts. Another factor in the economy of Southold is the summer resident and tourist trade. This will continue to expand as the Long Island limited access highway system and the residen- tial and industrial areas of western Suffolk County are extend- ed eastward. There are a number of unincorporated .communities in 13 Southold. The principal center of population is the in- corporated Village of Greenport. From the westerly border to Orient Point~ the unincorporated communities are: Mattituck, Cutchogue, New Suffolk~ Peconic, Southold, East Marion, and Orient. The railroad and/or main highway pass through each of these communities except New Suffolk, which is lo~ated 6n a peninsula in Peconic Bay. The following tabulation lists the U. S. Census Popula- tion of Southold and of the Village of Greenport, from 1910 to 1960, inclusive. TABLE 3 U. S. CENSUS POPULATION FIGURES TOWN OF SOUTHOLD AND VILLAGE OF GREENPORT 1910 1960, iNCL. Town of Village of Year Southold* Greenport ~910 10,577 3,0~9 1920 10,147 3~122 1930 11,669 3,062 1940 12,046 3,249 1950 11,632 3~028 1957 1R,607 2,645 1960 13,295 2,608 * Includes the Village of Greenport It is estimated that the present permanent population of th~ Town is approximately 16,000 and that there are about 2,500 persons residing in the Village of Greenport. It is also estimated that the average population of Southold during the three sumner months is approximately 32,000 persons. 15 III. WATER SYSTEMS AND WATER USE General The water system owned and operated by the Village of Greenport is the only public water system in Southold. This system provides fresh water for domestic use and fire protection service in areas within and adjacent to the Village. There are also a few small private water systems which supply water to groups of homes. Most of the homes and business establishments that are not supplied by the Greenport system obtain their water from small individual driven wells. Water used for irrigation comprises a major part of the water withdrawn each year from the ground. Most of the irri- gation water is from ~rilled wells from four to twelve inches in diameter and from 15 to 150 feet deep. Greenport Water System ° In 1898, the Village of Greenport acquired the small water system of the Greenport Water Company..The Village system has been expanded since that time to supply developed areas within and adjacent to the Village. The franchise area of the Village system prior to 1958 extended from Hashamomuck Pond easterly to Shipyard Lane in East Marion~and from Long Island Sound to Greenport Harbor. In 1958~ the Village purchased the system of the North Fork Water Company. It supplied water to built up portions of the unincorporated village of Southold. Its franchise area extended from Peconic Lane east to Hashamomuck Pond and from Long Island Sound to Peconic Bay. At that time, the Greenport system supplied about 1,000 consumers and the North Fork Water Company supplied about 280 consumers. The original well field of the Village of Greenport, designated as Well Field No. 1, was adjacent to the Power Plant at Moores Lane within the Village. The use of the No. 1 Well Field for'water supply was discontinued many years ago because of excess chlorides. It is now used for cooling water at the Power Plant. The water is returned to the under- ground ~upply. Later, additional wells were drilled at Well Field No. 2 on Moores Lane, about 2,000 feet north of the Power House and at Well Field No. 3, near the intersection of Moores Lane and North Road. As the system was expanded and withdrawals of water from Well Field Nos. 2 and 3 increased, a number of wells were developed in the East Marion area. This was necessary to avoid excessive withdrawals from the Moores Lane well fields. Well Field No. 5 on South Harbor Avenue in the Village of Southold is the field that supplied the North Fork Company, and it is in use at present. Recently, two new wells were developed north of Middle Road, near Norton's Lane in Southold. These wells have been connected to the Greenport :) and North Fork systems. They supplied about 54 per cent of the water in 1966. Plate A shows the location of the six well fields des- cribed above. It also shows the ~ocation of the six-inch and larger water mains in the Greenport system, includinz those purchased from the North Fork Water Company in 19~6 and the Connecting mains between the two systems which were constructed recently. The easterly and westerly limits of the franchise area of the Greenport system is also shown on Plate A. A plan for extending the system easterly is'under consideration. Table 4 below shows the total average daily water pump- age in gallons in the Greenport system from 1957 to 1966, inclusive. Year 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 TABLE 4 AVERAGE DAILY WATER PUMPAGE GREENPORT WATER SYSTEM Gallons Per Day 440,000 410,000 400,000 440,000 450,000 480,000 510,000 502,000 481,000 610,000 l? Maximum monthly water consumption occurs during the s~nmer months and the daily average during maximin months is about double the yearly average. Maximum daily consump- tion is about three times the average daily consumption for the year. Table 5 below lists the number of actiYe services and fire hydrants~ the quantity pumped in million gallons, and the percentage increases during the past ten year period. 18 TABLE 5 GROWTH OF GREENPORT WATER SYSTEM Active Services Fire Hydrants Water Pumped 195~ 1966 Increase Increase 973 1650 677 70 166 322 156 94 133 mg 222 mg 89 mg 67 In the early part of the past ten year period, the Village sold some water for farm irrigation, but practically no Village water is used for farm irrigation at this time. It is estimated that present p~mpage per service averages about 350 gallons per day and that pumpage per person averages about 100 gallons per day in the Greenport system. Domestic Water Use From Private Wells About 10~000 permanent residents~in Southold~ not supplied by the Greenport System, use an estimated average of 70 gallons per person per days or a total of 700~000 gallons per day. Some 15~000 summer residents use an aver- age of 80 gallons per day for two months, or a total of about 72~000,000 gallons per year. This is equivalent to an average of 200,000 gallons per day for every day in the year. The permanent and summer residents not supplied by the Greenport Water System obtain their water from individu- al wells. 19 Water Used For Irrigation For many years, Southold producers of potato~s, cauli- flower, and other'vegetable crops have utilized spray irri- gation to supplement rainfall during an average period of 16 weeks each sun~er. The amount of water used varies with the weather pattern and soil condition. On the average, best results are obtained when the ground receives the equivalent of about one inch of rainfall per week. About one half of this generally is con- tributed in the form of rainfall and the remainder by Spray irrigation from water pumped from shallow wells. These extend into the fresh water that is stored in the sand and gravel under the top soil throughout a large portion of Southold. 2O Most of the producers of vegetable crops have become experienced in the e~onomical use of irrigation. It is estimated that during an average season, water used for irri- gation varies from about 150,000 to 200,000 gallons per acre per year. At present, about 12,000 acres of vegetable crops are irrigated each year and the average amount of water with- drawn for irrigation is about 2,000 million gallons~ equivalent to about 5.5 million gallons per day for each day during the year. Total Water Withdrawal In Southold As shown in Tables 4 and 5, the total pumpage of water in the Greenport System in 1966 was 222 million gallons, or an average of about 600,000 gallons per day. The estimated water withdrawn for irrigation was about 2,000 million gallons, or an average of 5,500,000 gallons per day. Table 6 below lists the estimated current rate of with- drawal of ground water from wells in Southold in average gal- lons per day for each day of the year. TABLE 6 ESTI~L~TED 1966 WITHDRAWAL OF WATER IN ~OUTHOLD Greenport Water System Private Permanent Homes Private Sumner Homes Private Irrigation Systems Total Withdrawal 1966 Average.For Year Gallons Per Day 600,000 700~000 200~000 5,500~000 7,000~000 Quality of Water The quality of the fresh water from wells in Southold is generally very good, from a chemical and bacteriological standpoint. However~ chlorides caused by intrusion of sea water have caused cohtamination in certain areas clo~e to the shore line and to salt water inlets. The danger of future contamination caused by salt water intrusion is discussed in.the next two sections of this report. The hardness Of the water from wells of the Greenport System ranges from about 40 to 200 ppm~ or from soft to hard. In general, ground water in Southold used for domestic pur- poses and irrigation is moderately hard and is well within the limits of concentration of iron, manganese, chloride~ sulfate, and total solids prescribed by the U. S. Public Health Service for interstate carriers. Except where chloride content has increased because of salt water intrusion~ chlorides in Southold wells generally range from 10 to 50 ppm, as compared to the 250 ppm limit gen'erally considered the maximum concentration permissible for potable water. Southold's ground-water supply generally.is cool~ clear, and pleasing to the taste. Unlike certain areas of Long Island~ where there has been extensive residential development prior to sewer constructions'there have been no serious prob- lems caused by detergents in the well water. Greenport has a sewerage system~ consisting of a primary plant.with effluent discharging into Long Island Sound. Other areas should be se~ered at locations where there is a concentration of residential development and water is draw~ from individual shallow wells. 22 IV. GEOLOGY Subsurface Conditions Most of the wells in Southold terminate at comparatively shallow depths in upper Pleistocene deposits which are the source'of the fresh water used in Southold. Three deeper wells have been extended through older formations in-Southold.~ one in Orient Park (S189), one in Greenport (S491), and one at Nassau Point (S3123). The first two extended to bed rock and the third extended into the Magothy formation. Inform- ation obtained from these three wells, and also from other deep wells in the eastern part of Long Island, indicates that it is probable that the water contained in the older and deeper formations is too high in chlorides for domestic use and that no substantial quantities of fresh water for use in Southold may be obtained from these older formations. Bed rock in Southold is from about 1,000 feet below the surface in the western part to about 500 feet in the eastern part. Above the bed rock is the Raritan formation containing the Loyd sand member, the clay member, and post-Raritan de- posits which are of the Cretaceous age. Above the Cretaceous deposits are unconformed layers of Gardiner's clay and the upper Pleistocene deposits of varied depth, which consist of stratified and unstratified sand~ gravel, and gravel with some clay. Most of the ground-water used in Southold is with- AREA A MALCOLM PIRNIE ENGINEERS WHITE PLAINS~ N.~: - PARAMUS~ N.~. S6558 Gt~EA T PECONI C BAY IATTITUCK S6542 ~ CUTCHOGUE SUFFOLK LONG AREA ISL A ND B SOUND S6524 LITTLE /~ECON/C BAY AREA C s 6 93 GREENPORT EAST MARION ~r~ 90UTHOLD' L THE PREPARATION OF THIE EXHIBIT WAG FINANCIALLY AIDED THROUGH A FEDERAL GRANT FROM THE DEP~RTMENT OF HOUSING AND URBAN DEVELOPMENT~ UNDER THE PLANNING ASSIST- ANCE PROGRAM FOR THE BUREAU OF COMMUNITY PLANNIN~ NEW YORK STATE OFFICE OF PLANNING COORDINATION. IT WAS FINANCED iN PART BY THE STAT. E OF NEW YORK GARDItVER'S BAY AREA D FIGURE ORIENT St6787 TOWN OF SOUTHOLD SHOWN ARE WATER TABLE CONTOURS, dULY 1959 ( ONE FOOT INTERVAL AND DATUM MEAN SEA LEVEL) REFERENCE U.S.G.S. WATER SUPPLY PAPER 1619-S$, PLATE I000 BO0 0 I000 2000 · BASE MAP BY RAYMOND & MAY ASSOCIATES drawn from these deposits, which generally sand and gravel. Physical characteristics are shown in Table 4 of Water Supply Paper consist of coarse of this material 1619-GG by mechan- ical analyses of samples from 28 wells in various areas of Southold. More recen~ deposits, found along the shores and marshy areas, include beach and dune sand and gravel, in some areas mixed with clay. More complete discussions of the geology of Southold are given in U.S.O.S. Water Supply Paper 1619-~G, the Bulletin 0W-liS of the New York State Water Resources Commission, and the numerous references on the geology of Southold contained in those two reports. The current comprehensive Nassau-Suffolk water resources study with its deep well program should provide much valuable information on subsurface geological conditions in eastern Suffolk County. It should shed much light on the question of availability of fresh water from deep wells in Southold and on the lower limits of fresh water in the upper permeable glacial deposits. Surfac~ Conditions The almost continuous strip of high ground along the Long Island shoreline of Southold is comprised of till over- lying sand and gravel. The surface material in most of Southold is sand and gravel outwash covered by one to three feet of top soil, consisting of loam of various degrees of por6sity. These areas are generally excellent croplands. Surface clay of various depths exist in some areas. This is true of a sizable area along Moores Drain. This stream dis- charges a comparatively large quantity of fresh water into a salt water bay sou6hwest of Greenport at times of heavy rain- fall. Sand and gravel shore deposits exist along the north and south shore line of Southold. Orient Point Park consists of a long'narrow sand spit between Long Beach Bay and Gardiners Bay. Plate 1 of U.S.G.S. Water Supply Paper 1619-GG is a sur- ficial geological map of the Town of Southold. It is repro- duced and included herein as Plate B in the back of this report. The top soil in the uplands or croplands of Southold varies in permeability, as indicated by permeability tests of samples of loam taken at depths of from one-half foot to two feet below the surface. The surface soils range from sandy to silt loam, locally known as sassafras sandy loam, sassafras loam, and sassafras silt. It is suitable for production of large yields of vegetable crops when water is applied by spray irrigation during dry periods. The character of the soil and the gently sloping topography permit advantageous use of mechanical equipment for planting, cultivating, and harvesting crops. V. HYDROLOGY Recharge of Ground-Water The only source of replenishment of the underground fresh water supply of Southold is the rain which falls on the land. The sandy loam top soil and the underlying sand and gravel permit much of the rain to enter the ground. The gently sloping terrain and large areas of cultivated lands retard overland flows, as indicated by observations of run-off and stream flow during periods of heavy precipitation. It is estimated that the amount of rainfall that discharges overland to salt water each year averages about 15 per cent and may be as low as 10 per cent in extremely dry periods. A relatively large portion of rainfall returns to the atmosphere through evaporation from the soil and through the transpiration processes of natural vegetation and crops. These losses vary with distribution of rainfall, atmospheric condi- tfons, and temperatures. It is estimated that they range from 40 to 60 per cent of rainfall and average about 50 per cent. Assuming 10 per cent of rainfall is lost through run-off and 50 per cent through evaporation and transpiration, the re- maining 40 per cent is available for recharge. The estimated annual recharge ~n this basis is about 18 inches in the western part of Southold during a year'of average rainfall, and was about 12.8 inches during the record 3-year dry period 1963, 1964, and 1965. The total area of Southold is about 43 square miles. Re- ducing this to 40 square miles because of pavement and clay ~7 areas~ the computed annual average recharge in western Southold is about 12~500 million gallons in a year of average rainfall and about 8~900 million gallons in the three dry years of record. The recharge probably would average about ten per cent less in the eastern part of the peninsula~ where rainfall records indi- cate that average precipitation is somewhat less than in the western part. Storage of Underground Water Information obtained to date from records of well drilling operations in Southold indicates that the available fresh water supply is stored in the sands and gravels of the upper Pleistocene glacial deposits, which are 200 feet or more in thickness. These deposits contain fresh water and also salt water. Because of its lesser specific gravity~ the fresh water floats or rests on the heavier salt water. The surface of the fresh ~ater slopes from a few feet above a mean sea level in the central pa~t of each of the areas A, B~ C~ and D to sea level at the Sound~ bays~ and salt water inlets. The elevation of fresh water varies each year in accordance with rates of recharge and withdrawal of water by pmnping. Also~ a considerable amount of ground-water gradually seeps laterally through the porous underground material into the surrounding bodies of salt water. Much information is available as to ground-water levels in Southold from 194~ to date. Wells in Long Island are number- ed in accordance with a system established by the New York State 28 Water Resources Co~nission. Records of ground-water levels, as measured by static levels of water in wells throughout Long Island, are maintained at the office of the U. S. Geological Survey i~ Mineola. Plate 1 of New York State Water Resources Bulletin GW-45 shows by contours ground-water elevations in Southold in April 1950. Plate 3 of Water Supply Paper 1619-GG is a similar map of Southold, showing by contours levels of the water table in July 1959. This plate is-reproduced and included as Plate C at the end of this report. It shows the locations of wells in Southold by numbers. Measurement of static wate~ levels in these wells provide the water surface data from which the con- tours were established. As shown on Plate 1 of Bulletin GW-~5 and Plate 3 of WS Paper 1619-GG, the water table throughout Southold was considerably lower in April 1950 than in July 1959. This was caused by the fact that withdrawals for irrigation were greater and rainfall was somewhat less in the two to three year period that preceeded the July 1950 series of measurements. The limits of Areas A, B, C, and D, and Little Hog Neck and Great Hog Neck are shown on Plates A and C. For convenience, these limits and the underground water level contours in July 1959, taken from Plate 3'U.S.G.S. Water Supply Paper 1619-GG, are shown on Figure 4~ a reduction of the base planning map. The highest ground-water levels are in Areas A and B in the western part of Southold~ and gr0und~water levels in Areas C and D and in Little Hog Neck and Great Hog Neck are generally loweri As'shown on Plate C~ high ground-water levels inJuly 1959 were 7 to 8 feet above mean low tide in Areas A and B, and. o~ly -- 2 to 3 feet above the mean sea level in Areas C and D and 29 1 foot above sea level in Little Hog Neck and Great Hog Neck. The quantity of fresh water stored underground in each of the six island-like areas mentioned above depends on the vol~ne and permeability.of the materials which stere'the water. The lateral limits of each are shown on Plate C. There is sufficient information on static water levels to establish upper limits of the fresh water. However~ only a few wells in Southold are deep enough to establish the division or interface between fresh and salt water. Because of the general uniformity of the underlying sands and gravels, it is probable that the division between fresh and salt water conforms to the Ghyb~n-Herzberg principle or formula, This formula is in the form of the following equation~ in which h = depth of fresh water below sea level; t = height of fresh water above sea level; and g = specific gravity of sea water as compared to a specific gravity of 1 used for fresh water: h = t g-1 Using a specific gravity of 1.025 for sea water, the equation indicates that fresh water will extend 40 feet below sea level for each foot that it extends above sea level. This formula provides a reasonable method for determining the approximate division between fresh and salt water when both waters are stored in an unconfined fairly uniform material. Figure 3 is an idealized section of an island or peninsula] sho~ing the relationship of fresh water and salt water. Similar FIGURE NO. :3 SEA LEV~ND 'SURFACE · .., ¥-~... . '~.~.'?.*~;~.~ '?.'.::*'.':!i.:i. .~.: .".:..'.'.'?**'~ -.-...,:,., SA.D A.O GRAVEL .-.,' ~- ..~',' ~.:,~: -^~.- CONTAIN I N G '~'~ ~.' '~ . ",'. · :~',*' 7'* ' ~..'.- ' '-'.'.', ~. ~..,....{,.:~ ./..~. '&.~ . . ..._,,,:~;M'.. ~ ).,.,** *,, h FRESH WATER ~.'.'.".~:~ .,.;..,,.,,. .~ ~:.*";'--'~.'~"" ~,:""' ~'& 'F"~' '&' '.~;~"~'& · ~ '_~.*;'*'. ;^' .'"*.V'a* .':,.'f .~*~ .*.. '3;. :~'~-..~..~:.'..'.~.?.'..v.4~ °~.".~.'~.;. ',~:a.'<.~'. . ~ ~:.~: . ~' ~ .'~ ~" .'5. .% .~" 't" ~. ' Y',: '~'. ~.~. ".~ ~a ~ '*''. .~' u. '~.~'..~ ~ ~. : "v. .~'.~. .~'.,'~. ~ 3 '~'."f..'~' . ' ~. "~ ?~'~.'¥:~; ~.'~ ~:~.+.9.,~:.~.'~,'.",'.v'.j..:v:.~.,/.".4:v'e'.~.'.v:~.'.~'.v..~.~.~'~.:e~ 'v:[~;~ '~..~' v.~:.~.~ .~...~.. ,'.~,* ~'..^. · ~,.'~.... ~: .<. :.v'.~ ~ '~ '.~ ..~ ~,,.'?.-~.~'-.~ SAND AND GRAVEL CONTAINING SALT WATER ,'z.~'.~"."~'-'~: ~::,. *:~.'^' :,~. '.¢"*~':':?,::;,:,,,.'.":'.".'::?:-.¥~'. ¥ *.;':v'?.~ .,.~;.* :~.:':~:~..' .;?. ¥'-..' ~.;~.~ .~,'~ *:.~'~.."-'~.^"..~?.~ ,: ~ =.'...:~...v: :..?.'.~...::.'.v...~ :.:-:~. : . :~.~v'. ~,.~,'../,..~.~.~.?~. :.' .:.~.;,:?. :,.. ~.~...~ :~.~: ...,.;.:.:/: ~. .'~ ,.-: : .,..? ~/.~...: ...,. ~'...? ;v.., ~..~.~-.~..~ ,...~.,. :<*:.., ~:.~..+,~..~ .,...,..,..,~* ~,. ^ ~.~...~ .~:~-.*.~. ~ ,~ .,~: .~ ~.,:,~ ..~: ~-...,'. ~ '.,.:.,.~. ~ .~.:.'..~.~?.. =...~.~,... · "~" '.~."<"~'.'"~.~;..'^'~:~' '<.'.~. ': '" · 'Tr:~' ','/ ' .' '4 ~.' '~,':'~.": '~,:"4.~::k "+.~.'~.-/.'a. · .~.~.-..,~.~"<." · · -~' I~'~'.~. * ~..--~-Y...~.,~.,d '' ~.'~e:~' ~ e~"k' "Y.'~'~'. .... .e.v'l.:T-' :~..~x.~.. ~"~'v.'~.'~'¥'- v"~* TYPICAL GEOHYDROLOGIC SECTION SHOWING RELATION OF FRESH AND SALT WATER ( ACCORDING TO THE GH.YBEN- HERZBERG PRINCIPLE ) MALCOLM PIRNIE ENGINEERS WHITE PLAINS~ Nfl.- PARAMUS~ N.J. section, s are ~nclu~ed in a number of hydrological studies to illustrate application of the Ghyben-Herzberg principle. As an aid in estimating tt~e approximate quantity of water stored in each of the six hydrological sections~ Plate 3 was included in Water Supply Paper 1619-00. Plate D of this report.) It shows, by a and five transverse sections~ the upper~ (It is reproduced as longitudinal section lateral, and lower limits of the underground fresh water reservoir. The inter- faces or zones of' diffusion between fresh water and salt water were obtained by applying the Ghyben-Herzberg principle to the water table elevations in July 1959, as shown by the ~ections on Plate D. In WS Paper 1619-GG~ Crandell computed the volume of the fresh water aquifer in each area~ and applied a specific yield of 22 per cent to obtain an estimated total volume of fresh water in storage. Table 7~ which follows~ shows his estimated volume of fresh ground-water in storage in:July 1959. Although these estir~tes can be considered only as approximations~ they are based on reasonable assumptions as to underground conditions. They indicate that over 90 per cent of the fresh water storage at Southold is in Areas A and B and that less than lO per cent is in Areas C and D, Little hog Neck and Great Hog Neck. 31 TABLE Estimated Volume Estimated Volume of Deposits Satu- of Fresh Water rated with Fresh in. Storage Water Area ( Mill. cu. ft. ) .( Mill. Gallons ) A 28,200 46,000 B 82,000 134,000 C 6,400 10,400 D 6~ 400 10,400 Little Hog Neck 600 1,000 Great Hog Neck 2,900 4,700 12--~6-~ 500 20--6-g, 500 Note: Figures in Table 7 are taken from WS Paper 1619-GG, pp GG-23 and GG-24 Variations in Ground-Water Levels Figures 5, 6, and 7 show variations in ground-water levels in certain wells in Areas A and B from 1949 to 1966, inclusive, and in certain wells in Areas C and D from 19~9 to 1966, inclusive. The low ground-water levels in 19~9 and 1950 were caused by excessive withdrawal for irrigation purposes. The very low'ground-water levels in 1966 resulted from record low rainfall from 1963 through 1965. Deficient rainfall also caused comparatively low ground-water levels in 1957. .-~ 3.0 l-- hi -- 2.0 --I I. 6.0 4.0 7.0 6.0 5.0 4.0 2.0 1.0 1949 1950 ,~ ~ ~ 1951 ~ = .~ 1952 1953 FIGURE 1954 1955 1958 1960 1961 1965 1964 1965 1966 1967 1968 NO. 5 7.0 6,0 5.0 4.0 $.0 2.0 6.0 5.0 4,0 2.0 1.0 9.o FIGURE NO. 6 9.O 8.0 7.0 Z -- 4.0 Z ~ 4.0 3.0 2.0 1.0 0 8.0 7.0 6.0 5.0 4.0 2.0 4.0 3.0 2.0 1.0 0 1949 1950 1951 1952 J953 1955 1961 1962 1963 1964 1965 1967 1968 FIGURE NO.7 ,5.0 5.0 4.0 ~J bJ 2:.0 .-I 0 ~958 1959 1960 1961 i962 1963 1964 1967 4..0 3.0 2.0 1.0 0 5.0 ,4.0 $.0 2.0 32 VI. AVAILABILITY OF FRESH WATER Salt Water Intrusion The danger of salt water intrusion is the principal limiting factor in the amount of water that can be safely withdrawn from the ground in various parts of Southold. This is because the fresh water in storage is Surrounded on all sides and beiow by salt water, as shown on Plates C and D. The danger of ~alt water intrusion is more serious at locations where the static level of the fresh water is only a little above mean sea level. This is particularly true in Areas C and D, Little Hog Neck and Great Hog Neck, and areas adjacent to bodies of salt water in the other parts of Southold. With- drawals of water from these areas for domestic use and irri- gation can not be increased to any appreciable extent without causing contamination of the supply by either lateral or verti- cal intrusion of salt water. A number of instances of salt water contamination in Southold are recorded in Water Supply Paper 1619-GG and other reports. In some instances, the contamination has been caused by lateral movement of salt water into the fresh water where the wells were located close to bodies of salt water. Excess chlorides caused by vertical movement of the salt water has been experienced in the past, particularly during periods of low rainfall~ in water withdrawn from wells used for irrigation and water supply. 33 Estimated Safe Yield A number of factors affect the quantity of fresh water that may be safely withdrawn from the ground in various parts of Southold. The principal factors are amount and distribution of rainfall~ character~of surface and underground materials~ purpose for which the land is used, location of points of with- drawal in reference to salt water, and the elevation-of and variations in ground-water levels in the general vicinity of the points of withdrawal. Records of rainfall~ ground-water levels, and underground conditions in Southold developed during wet and dry period~ for the past 15 to 20 year period generally are available. To a lesser.degree, records of the. quantity and chloride content of water withdrawn in various parts of the Town are availab, le and are helpful in considerations as to the safe yield of under- ground water during periods of low rainfall. Based on a study of the records and experience on with- drawal of water during the past 15 or 20 year period,'it is estimated that the approximate yield of Southold's ground-water supply is approximateiy 40 per cent of recharge during periods of three consecutive years. In Section V of this report, it was stated that estimated annual recharge during periods average rainfall is about 12~500 million gallons and is about 8~900 million during extremely dry periods, such as those ex- perienced recently. Using 40 per'cent of recharge for yield, the estimated yield in a period of average rainfall would be 5,000 million gallons, or an average of 14 million gallons per day, and during a three-year period of minimum rainfall, the yield would be about B~600 million gallons, or an average of lO million gallons. For purposes of this study, an average, of l0 million gallons per day will be considered as the safe or dry weather yield of the underground water supply of Southold. At present, an average of about 7 million gallons of fresh water per day are withdrawn for domestic and irrigati0nal uses. In accordance with the above estimates of available y~eld, an additional withdrawal of about l0 million gallons per day could be made during years of average rainfall. However, the safe yield of a water system must be based on years of record low rainfall. This indicates that withdrawals of l0 million gallons, or ~ million gallons in excess of 1966 withdrawals, may be safely made in the future under conditions of withdrawal designed to prevent salt water intrusion .... Relationship of Available Ground-Water to Plannin~ As shown in Table 6 of Section III, total estimated with- drawal of ground-wate~ was an average of 7 million gallons per day for &ach day during the year o~ which an average of 5.5 million gallons per day. was used for irrigating vegetable crops. Assuming that the number of acres .irrigated and irrigation practices 35 will remain about the same as in 1966, the safe yield estimate of 10 million gallons per day in dry weather indicates that about 3 million gallons per day will be available for domestic ~se. It is estimated that future average per capita water use in Southold will be about 120 gallons per day for permanent residents and about 80 gallons per capita per day for an average. of two months per year for summer residents. This is equivalent to 16 gallons per capita per day for each day of the year. The 120 gallon per day allowance for permanent residents is higher than present use and ,is based on the assumption that domestic, 'commercial~ and light industrial, use will increase in the future. It is probable that the number of seasonal residents will increase in the future, as Suffolk County developments extend in an easterly direction. Assuming that summer residents increase three-fold to abbut 45~000 persons within the'next 20-year period: this will mean additional water consumption of about 500~000 gallons for each day in the year. This will ~eave about 2.5 million gallons for an increase in permanent residential use. Assuming a per capita consumption of 120 gallons per day, the remaining 2.5 million gallons will provide for more than 20,000 persons, or a total of 36,000 permanent residents, in addition to 45,000 seasonal residents. As stated above, these estimates assume that the amount of water used for irrigation will be equivalent to 5-5 million gallons per day for 365 days a year. Irrigation water use of 200,000 gallons per acre per year is equivalent to'the consumption of about 5 permanent residents, or more than 30 summer residents. If withdrawal of water for irrigat&on'is decreased in the future, the safe yield will provide a supply for a greater number of additional permanent and/or summer residents than indicated in the previous paragraphs. .Conversion of Salt Water Considerable pzogress has been made during recent years in research, and in pilot plant and plant scale operations related to conversion of salt and brackish water to fresh water. However, costs of construction and operation of saline water conversion plants are generally prohibitively high, except where an adequate supply of fresh water is unavailable. Several operating plants of 3 million gallons and less per day are tin operation or are in the planning or construction s6age of development. These include in the Virgin Islands, Saudi Arabia, Naval Base at Guantanamo Bay~ Cuba. operating plants lodated North Carolina, and t e However, the cist of con- struction, maintenance.~ and operation of these plants is very high. Lower costs are estimated for large plants which will combine power production with salt water conversion by utili- zation of atomic energy. F~nancial arrangements of a large plant of this type at Long Beach] California, recently have been completed. This plant is being designed to produce 150 million gallons of fresh water per day, as well as large quantities of power for use in the Los Angeles area. Condl- tions at that location are comparatively favorable for a large atomic power and saline conversion plant. The New York State Atomic and Space Development Authority has been developing plans for a combined atomic powered elec- trical generating and saline water plant at Surfside in the Town of Riverhead. The initial water plant will have a capacity of about one million gallons per day, with provision for future increases in capacity. Preliminary plans for this installation have been in progress for some time. At present the plant is being'designed, and operation is scheduled for 1970. An agreement has been made with the Town of Riverhead to purchase one million gallons of fresh water a day at an initial cost of 35 cents per t000 gallons, with a provision for a gradual increase to 45 cents per 1000 gallons in the first 10-year period. The plant will be located on Long Island Sound, relatively close to the border line of the' Towns of Riverhead and Southold. The capacity of the Power Plant will be 2500 kilowatts. The Long Island Lighting Company has agreed to purchase electric power from the install- ation at a cost of 15 mills per kilowatt hour. There is more than sufficient ground-water available in the western portion of Southold for present and probable future needs, unless an unforseen industrial demand for fresh water develops. It does not appear to be economically feasible for Southold to utilize converted sea water from this plant for domestic, commercial~ and irrigation use in the foreseeable future.. However, if industries which use a large quantity of fresh water are developed in the western part o£ Southold, they may find it advantageous to obtain water from the proposed Surfside Plant. VII. PROTECTION OF GROUND-WATER RESOURCES It is essential that Southold employ every available means to protect its limited ground-water supply. Following are me~hods 1. 2. 4. that should be investigated and considered: Control of future water withdrawals. Location and spacing of wells. Extension of public water facilities. Discontinue approval of projec£s which include dredging channels inland from salt water estuaries or bays. Construction of dikes across drainage channels near shorelines. Recharge of '~quifer with surface waters. Control of Future Withdrawals At present the installation of wells for public water supply and commercial and industrial use is subject to the approval of the State Water Resources Commission. State regulations also require filing of data for record purposes on wells other than small wells serving individual homes or buildings. However, th~ state do~s not exercise control over installations and the amounts of water that may be withdrawn from irri~ation wells. The location, spacing, and amount of water withdrawn from large wells are important factors in the protection of the fresh water supply in Southold from salt water intrusion. The advisability of the Town exercising control over future well installations from a legal, engineering and administrative standpoint should be given serious consideration. 'Location and Spacing of Wells The location, spacing· and depth of wells of large capa- city depend upon a number of factors· and each new installation should be considered individually. Such wells should be constructed at some distance from salt water and at locations where minimum static ground-water levels are two feet or more above mean sea level. In general, they should be spaced at least 500 feet apart and about 1000 feet from the shore of salt water bays or inlets. Samples of water should be taken and tested for chlorides· particularly at times of low ground- water levels and heavy withdrawals. Pumping should be dis- continued whenever a definite increase in chlorides is indicated. Wells to provide large'quantities of water for public water supply should be constructed in the ceutral portions of ~eas A and B · where ground-water levels are comp~ratlvely high. Extension of Public Water Supply Facilities The Greenport Wate'r System supplies water to about one third of the total permanent population of Southold. Most of the remaining permanent and summer residents are supplied by shallow individual wells. The water'from many of the wells that are close to salt water is of poor quality. In areas where homes are not very far apart· there is always the danger of pollution. Also, excess removal of fresh water from the ground-water table near the shore eliminates the existing natural fresh water barrier. As the population becomes more dense in many areas of Southold, public water supply facilities should be provided. The Greenport Water System should be gradually extended east- ward along Main Road to supply water to the unincorporated villages of Orient and Orient Point. The East Marion Wells and a new well near Main Road north of Orient village could be used to advantage to supply the comparatively small water consumption in this part of Southold , which has been designated Area D. Certain areas adjacent to the Main and North Roads, and along the southerly shore line of Southold, between the pre- sent limits of the Greenport.Water System and Mattituck, including built-up areas of New Suffolk and Mattituck, should have public Water service with adequate fire protection facili- ties in the near future. This service could be supplied best by extension of the Greenport System or by a new system developed and operated by the Suffolk County Water Authority. Both organizations are experienced and competent to provide efficient service. Decrease in insurance costs and increase in property values resulting from an adequate water system will compensate to a considerable extent £or the cost of the service. Inland Salt Water Channels In recent years, approval has been given to extending inland from salt water bays or estuaries certain dredged channels to provide for development of marinas or water re- sidential property. As shown on Plates A and B, in the vi- cinity of each natural or dredged channel extending inland, the contours representing very low ground-water levels extend for a considerable distance from the shoreline of the estuary. This provides a shorter distance of travel, and thereby in- creases the loss of fresh water from storage and the possibility of salt water intrusion into nearby well supplies. Recently, applications for approvaI of such projects have been made. There are many sites aloug the water front of Southold where such developments can be made at low cost. Many future applications for approval of construction of inland salt water channels can be expected unless approvals for such developments are denied by the Town. ~umerous coves and bays along the South Shore provide sites suitable for marinas and water fronb residential properties, and it is not necessary to endanger the underground water supply by the extension of salt water channels inland. Drainage Channel Dikes The surface contours on the Geological Survey maps of Southold and field observations indicate that there are a number of drainage channels that extend to the south shore line of Southold~ across which it may be feasible to provide low dams or dikes to restrict surface and underground drainage of fresh water into salt water inlets or bays. In some instances it might be advisable to construct excavated ponds above the dikes to store fresh water at elevations above mean tide level. Available information indicates that many of the drainage basins are covered by marsh deposits i'which Would tend to store the fresh water above sea level. Some of the dikes would serve to convert existing salt water inlets into fresh water ponds. It probably would be advisable to provide sheet pile cut-offs under some of the dikes. Inlet and outlet facilities in the dikes will be necessary to control the water above and below each dike. Each installation would provide a water 'barrier which would retard fresh water underflow from the ground-waker storage basins to the sea. The locations which offer the most promising possibilities for this type of installation are numbered 1 to 16, inclusive, on Plate A. Surveys and borings are necessary at each location to establish the feasibility, effectiveness, and cost. Recharge of Surface Waters The State Highway Department and some of the Counties and Towns in Long Island have designed highways and, in some instances, storm drainage systems to discharge into excavated recharge basins extending into the coarse sand and gravel material. Some have been constructed in Southold. This practice should be continued. For a number of months each year, the Village of Green- port pumps water from a pond located on Moores Drain and dis- charges it on lands a. round wells in Well Fields Nos. 2 and 3. The water level in the wells is raised and an increase in the yield results. Much of the surface of the drainage area of Moores Drain is comparatively impervious, and during periods of heavy rainfall large amounts of fresh water are discharged into Pipes Cove. Additional storage ponds for recharge should be constructed on Moores Drain. The sewage of Greenport is now treated in a primary plant and the effluent is discharged through a subaqueous outfall extending into Long Island Sound. Extensive experimental methods for complete treatment of the effluent from its activated sludge treatment plant and discharge of the effluent into the ground to form a fresh water varrier are being con- ducted in Nassau County by the County and the U. S. Geological Survey. This program includes the construction of a complex 'recharge well and nearby test wells to permit a series of tests on the effect of th~ recharge of the treated wastes on the water-bearing sands at various depths. It is expected that this program will provide considerable data relative to the feasibility of treating large quantities.of liquid wastes to · such a degree that they can be returned to the ground and in- crease the available underground fresh water supply under conditions such as those prevailing in Long Island. Similar treatment and recharge of ground-water aquifer have been' undertaken in California and other states. At present it is not necessary nor economically feasible for Greenport to change its method of disposal of sewage. However, the aforementioned method should for disposal of sewage from Greenport and areas of Suffolk County in the future. be given consideration other thickly settled VIII. Fishers Island Water Resources General Conditions Fishers Island is in Long Island Sound, about 11 miles northeast from Orient Point and ? miles southeast from New London. It is about 6 miles long and about one-half to a mile in width, and its area is 4.2 square, miles. The inset on the right hand portion of Plate A shows the main features of the Island including roads, ponds and the location of the water supply mains. Fishers Island has long been famous as an attractive summer resort. Its rolling hills, irregular shoreline and large areas of natural woodlands provide exceptionally beau- tiful scenery. Most of the easterly portion of the Island is owned by The Fishers Island Club and its members. In this section there are a number of summer estates that were established many years ago, and also extensive areas of undeveloped fields and woodlands. A large part of the westerly half of the Island is owned or controlled by Fishers Island Farms, Inc. Many people spend all or part of the summer in this part of Fishers Island. ~ ' Portions 6f the western part of the'Island have b~en used'from time to time deactivated. A ferry Many persons use privately owned boats and planes for military e~tablishments, but these hav~ been from New London provides access to the Island. to reach the Island. The climate is about the same as in other parts of Southold. However, the topography and underground conditions are different. There are hills up to about 160 feet high in both'easterly and westerly portions of the Island. Much of the land is undevel- oped and generally is less pervious than the mainland areas of Southold, and a much larger portion of the rain drains overland to fresh water ponds and to the surrounding coves and bays. Glacial deposits occur in some areas and these are possible sources of fresh water, but the water from wells in these deposits generally is high in iron and in some cases it is high in chlorides. ~opulation and Water Consumption · The permanent population of Fishers Island varies between 400 and 500 persons. It is estimated that maximum peak popu- lation during summer weekend periods is about 5,000 persons. The Fishers Island Estates Corporation owns the wate~ system which supplies water on a retail basis to the eastern part of the Island and, on a wholesale basis, to Fishers Island Farms, Inc., which owns and operates the distribution system in the western part of the Island. As indicated on Plate A, these two systems provide water service to most of the developed areas throughout the'Island. The following tabulation lists the amount of water pumped from the treatment plant each month in 1965 and in 1966, expressed in terms of 1,000 gallons per month. 48 Table 8 WATER PUMPED FROM THE FISHERS ISLAND TREATMENT PLANT (1:000 GALLONS PER.MONTH) 1965 1966 January 2,366 2,288. February 2,384 2,272 March 1,772 2,266 April 2,244 3,037' May 6,401 4,033 June 10,087 7,589 July 14,419 14,123 August 11,770 12,060 September 7,185 '6,215 October 3,665 4,279 November 2,708 2,882 December 2,420 4,780 Total Ay. Da%ly- 186 170 Ay. Day Max. Month 465 458 Av. Day - Min. Month 57 73 As shown in Table 8, average daily pumpage in 1965 was 186~000 gallons per day. During July, the' month of maximum consumption, it was 465,000 gallons per day. Maximum daily use occurred on July 14, 1965, when pumpage of 628,000 gallons was recorded. There is no indication that there will be a substantial increase or decrease in water consumption during the next l0 or 20 year period. 49 Existin~ Water System The main source of water supply is from two shallow fresh water Ponds, Barlow Pond and Middle Farms Pond. Normally, both Ponds provide gravity flow to the suction of low lift pumps which raise the water for treatment to a filtration plant that has a nominal capacity of one million gallons per day. The 1963-66 extremely dry period depleted the available storage in the two Ponds to an alarming degree, and a 6-inch test well and an 8-inch gravel packed well wSth 12-inch outer casing were installed near Middle Farms Pond in the summer of 1966. Water was discharged from this well into the Pond during the latter part of 1966. Initial tests of the well water indicated that it contained more than desirable quantities of iron. Possibly the water quality will improve with use. The use of these wells was discontinued early in 1967 when the Ponds were filled by surface rhnoff resulting from normal rainfall. The water treatment plant is located near Barlow Pond. It is a well designed and operated'~lant with a nominal capacity of i million gallons. ~This plant is adequate for ~resent and probable future use. The high lift pumps are rated at 800 gallons per minute. The clear water storage basin at the plant has a capacity of 400,000 gallons. 50 It is feasible to add storage to the surface supply system by utilizing'Treasure Pond, A portion of a larger pond, Island Pond, could be utilized for storage.by providing dikes to main- tain the northerly portions of the Pond as a fresh water Pond. This Pond became salted during a hurricane storm and the lower portion is now used to produce seed oysters. The new well and test well, which have a combined installed pumping capacity of 250 gallons per minute, are available for supplementing the surface supply, if this is necessary. The two new wells provide means for increasing raw water supply when mixed with stored surface water. Additional pumping and testing should be carried out p~riodically to determine whether iron content has been reduced to satisfactory limits. Should unexpected increase in demand occur, iron removal and chlorination facilities could be added to permit regular use of the well water. The distribution system consists of a principal 10-~nch feeder main extending easterly and westerly from the treatment plant, and smaller branch mains. A million gallon capacity stor'age reservoir, located on Chocomount Hill about 1-~ miles east of the treatment plant, floats on the system and controls the static pressure. A 500,000 gallon storage reservoir, known as the Bell Hill Reservoir, originally provided stbrag~ on the westerly part of the sys6em. This is an uncovered reservoir and it is understood that it has not been used for many years by order of the State Health Department. 51 There are approximately 80 hydrants in the system. Hydrant tests made by the New York Fire'Insurance Rating Organization a few years ago indicated that only a few hydrants could deliver 500 gallons per minute and many of them could not deliver 250 gallons per minute at 20 pounds per square inch residual pressure. A detailed investigation of the adequacy of the distribution system is beyond the scope of this report. However, it Is apparent that the system is inadequate to provide sufficient water to many of the existing hydrant~ in both easterly and westerly parts of the Island. A competent water works consul- tant should be engaged to make a detailed investigation'and report on the need for additional distribution storage and/or~ mains and the ~ecommended improvements should b~ undertaken 4 as soon as possible tO provide sufficient water at hydrants ~ for adequate fire protection. General 52 IX. CONCLUSIONS AND RECOMMENDATIONS Southold has no surface streams or lakes of appreciable size, and its sole source of fresh water is ground-water stored in the relatively pervious glacial deposits which exist through- out most parts of the peninsular portion of the Town. Most of the wells which withdraw water for public water supply, irrigation, and individual domestic use are which extend from a few feet to deposits. Estimates of Safe Yieid Rainfall in Southold averages about During the record three year dry period comparatively shallow wells about 100 feet into the glacial 45 inches a year. ( 1963,. 1964, and 1965) the average was only about 32 inches, and in 1965 only 26.? inches were recorded at the Cutchogue Station. A relatively large portion of the rainfall returns to the atmosphere through evaporation from the soil and through the transpiration of natural vegetation and cultivated crops, and about 15 per cent flows overland to salbwater. It is estimated that 50 per cent of the rainfall enters the ground and that about 200 million gallons of fresh water is stored above saltwater during averaMe periods of rainfall. However,~ onl-y a portion of this can be withdrawn without causing contamination of the fresh water supply with saltwater. Some of the stored fresh water flows laterally to the various bodies of water which almost completely surround Southold. Furthermore, it is not safe to withdraw fresh water from any portion of Southold to such an extent that the ground- water level is below I or 2 feet above mean sea level because of danger of contamination by saltwater. As described in Section VI of this report, the danger of saltwater intrusion is the principal limiting factor in the amount of fresh water that can be safely withdrawn from the 'ground in various parts of Southold. In this section of the report, it is stated~that the estimated safe yield is about 6,000 million gallons per year during normal periods of rainfall and about 3,600 million gallons per year, or an average of about l0 million gallons per day in an extremely dry period. These estimates are based on a number of factors, including records of ground-water elevations, withdrawals for various purposes, and hydraulic computations based on data obtained from various sources. Fortunately, there have been extensive past investi- gations made by representatives of the U. S. Geological Survey and others on ground-water conditions in Southold which provide muc~ useful data. Estimates of Population and Water Use It is estimated that the present population of Southold is about 16,000 and that peak population in summer months is about two times this. figure. The water System owned and operated by the VillaEe of Greenport is the only public wate~ system %n Southold. It supplies more than 600,000 gallons per day of water to about 53 5,000 persons in areas within and adjacent to the Village. It is estimated that about 10,000 permanent residents of Southoldt~ not supplied by the Greenport system~use an average of about 700,000 gallons per day and that some 15,000,000 summer residents use about 72 million gallons per year or the equivalent of an average of 200,000 gallons for each day of the year. The total estimated withdrawal of water for domestic use now averages 1.5 million gallons per day. Approximately 12,000 acres of vegetable crops are irrigated during dry periods each year. It is estimated that average withdrawals for this purposeis about 5.5 million gallons per day, and that total withdrawals average about ? million gallons per day. The quality of well water is generally good. It ranges from soft to hard and at most locations it is moderately hard. Iron content is greater than desirable in the water from certain wells. There have been no serious problems caused by detergents, but this may be a future these areas?are sewered. system. 'The above estimates problem in developed areas, unless The Village of Greenport has a sewerage of safe yield and Present withdrawal indicate that at addition to present withdrawals, period of record. Assuming that for irrigation remains constant, sufficient water and about 45,000 least 3 million gallons per day of water, in are available during the driest the amount of water withdrawn the additionai Yield will provide for a total of about 35,000 permanent resi~entsl seasonal residents. Average irrigation use is 54a equivalent to about 200,000 gallons per acre per year, or about the average consumption of 5 permanent residents or more than 30 summer residents. The above estimates indicate in various parts of Southold must with sound planning for the most effective utilization in various points of the Town. The water resources of Southold are limited to an amount which does not greatly exceed present use. It is essential that Southold must employ every available means for protecting this limited ground-water supply. The following suggested methods should be investigated and be given consideration: 1. Control of future water withdrawals. 2. Location and spacing of wells. 3. Extension of public water facilities. 4. Discontinue approval of projects which include dredging channels inland from saltwater estuaries or bays. 5.Construction of dikes across drainage channels near shorelines. "· The how they Recharge of aquifer with need for considering each should be implemented are of the report. that the available ground-water be considered in connection of lands surface waters; of the above methods and discussed in Section VII Possible Supplies other than Ground-Water The feasibility of utilization of fresh water sources other than ground-water has been considered. One of these 55 sources is water from the atomic power and saline conversion plant now being planned by the New York Atomic Space Development Authority. This plant will be located on Long Island Sound, at Surfside in Riverhead, not far from northwesterly part of Southold. This project is described on pages 37 and 38 of the report. The present contractual cost of water, 35 cents per 1000 gallons at the plant with a gradual increase to 45 Cents, is far greater than the cost of ground-water. It does not appear economically feasible for Southold to utilize converted sea water from this plant in the foreseeable future. There is an excess of ground-water in portions of the Town of Riverhead, east and west of the built-up sections. Should industrial development in the westerly portion of Southold un- expectedly increase, it may be possible to utilize some of this excess ground-water. Fishers Island Water Resources Fishers Island, an attractive summer resort in Long Island Sound near the Connecticut and Rhode Island shorelines, is one of the five islands within the Town of Southold, and it is included in the study area covered by this report. It is about 6 miles long; its area is 4.2 square miles; and the permanent population is about 450 persons, with a peak of about 5,000 persons during holiday weekend periods. A privately owned central water supply system extends throughout the Island. The principal source of water is surface water which is drawn from two small relatively shallow ponds in the central portion of th~ Island. The surfaces of the Ponds when full are only a few feet above sea level. Average daily water use is about 200,000 gallons; average daily use in July, the peak month, is about 4?0,000 gallons;· and a maximum daily pumpage of 465 gallons was recorded in July 1965. The available water in the two presently used storage~ reservoirs was drawn down, in the su~uers of i965 and 1966, to a degree that caused concern. A test well and larger well were driven in the summer of 1966 and used to supplement the water in one of the ponds during the latter part of 1966. Since then, more than normal rainfall has increased storage,and the use of the wells has been discontinued. Tests in 196~ indicated that the well water contained much more iron than is desirable. Two other ponds are available for additional storage and it may be feasible to draw down some of the ponds lower than presently can be accomplished,'without causing saltwater in- trusion. This can be determined by a testing program of water'in the ponds. Should the wells continue to produce water high in iron content, iron removal facilities can be provided at the wells and, if necessary, they could be regularly used. The existing treatment plant, which has a nominal capacity of one million gallons per day, is adequate and well operated.~ The distribution system comprises a main 10-inch feeder extending easterly and westerly from the treatment plant which 57 is in the central portion of the Island, and a number of smaller mains. At present, there is only one storage tank in the dis- tribution system which is located on a hill about 1~ miles easterly from the treatment plant. A second tank ~s needed in the westerly part of the Island. Hydrant flow tests made a few years ago indicate that the distribution system is inadequate to provide proper quantities of water for fire protection purposes. This situation has been confirmed by our present investigations. It is recommended that competent water supply engineers be re- tained to make a detailed study of the distr±bution system and Storage facilities and to recommend needed improvements.