Hydrogeology of the Huntington-Smithtown area Suffolk County, New York By E. R. LUBKE CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1669-D Prepared in cooperation with the Suffolk County Board of Supervisors, the Suffolk County Water Authority, and the New York Water Resources Commission UNITED STATES GOVERNMENT PRINTING OFFICE. WASHINGTON : 1964 UNITED STATES DEPARTMENT OF THE INTERIOR STEWART L. UDALL, Secretary GEOLOGICAL SURVEY Thomas B. Nolan, Director For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.G. 20402 CONTENTS Page Abstract______________________________________________________ Dl Introduction.. _________________________________________________ 3 Scope and purpose of investigation____________________________ 3 Location and extent of area___________________________________ 3 Previous investigations________________________________________ 3 Acknowledgments _____________________________________________ 5 Well-numbering system._______________________________________ 5 Geography__ ___________________________________________________ 6 Physiography and drainage.._._._-_____-__-___-_-__________-__- 6 Culture._____________________________________________________ 7 Climate.__-__-----__--__---_-_____-__-_--_-___-__________ 8 Geologic formations and their water-bearing character________________ 9 General features_____________________________________________ 9 Bedrock_________-_-______-.__._____.____._...____________ 10 Upper Cretaceous series________________________________________ 11 Raritan formation ________________________________________ 12 Magothy(?) formation.____________________________________ 13 Pliocene(?) series_-_-_-_-_____--____-__-__-_______-_--_-------- 19 Mannetto gravel-_--_--______-_-__------__-_--_-----_---_- 19 Pleistocene series______________________________________________ 20 Undifferentiated deposits of Pleistocene and Pliocene (?) age_ __ 23 Upper Pleistocene deposits________________________________ 25 Recent series________________________________________________ 27 Ground water-._____-__--____-_-_______-______-___-___-____-____ 27 Water-bearing units____-_________-___-___________--__-_----_ 27 Perched ground-water bodies_-___-_--__-_----_---_---------- 28 Shallow aquifer__-_-_.--___.____-___-______--_-____-_-__ 28 Intermediate aquifer.--...-.___-________-__-__-_____-_---__ 33 Deep aquifer__-_____-__-_______-________-_____--_-_-_--_ 36 Recharge.___-___-_-________--_____-_______-_-__--__--_---_--- 40 Movement_ _--_-________-_____________-_--___-_-__-_-_------ 41 Discharge _--_______-________-_____._______-_____-_--_--_-_--- 44 Pumpage_____________________________________________________ 45 Surface water_____________________________________________________ 48 Chemical quality__________________________________________________ 49 Temperature_ _-_-____-__________ _______________________-____--- 52 Contamination. ___________________________________________________ 52 Conclusions_ _ ___________________________________________________ 57 References cited.__________________________________________________ 64 Index._______________________.___-_____._._______________--_-_--- 67 in IV CONTENTS ILLUSTRATIONS [Plates are in pocket] PLATE 1. Well-location map. 2. Geologic map. 3. Contour map of buried Cretaceous surface. 4. Geologic sections. 5. Water-table contour map. 6. Distribution of public supply and industrial pumping. Page FIGURE 1. Index map_________________-_--_-_---__-_______ D4 2. Population trends---_____--_--------_-------------_-_-_- 7 3. Map of clay unit of Smithtown_______.___ __ 22 4. Hydrographs of four wells____________ 31 5. Hydrographs of two wells and monthly precipitation_______ 32 6. Piezometric contour map of intermediate aquifer ____________ 34 7. Hydrogeologic section at South Huntington____-_-_____.__ 36 8. Hydrographs of wells in the shallow and intermediate aquifers. 37 9. Piezometric contour map of deep aquifer __________________ 39 10. Hydraulic profile X-X'. _______________________________ 43 11. Withdrawals from public-supply systems ___________________ 46 12. Map of sites for temperature and chloride determinations__ 53 TABLES Page TABLE 1. Summary of average monthly and annual precipitation at sta­ tions in or adjacent to the Huntington-Smithtown area. _____ D8 2. Summary of the stratigraphy and water-bearing properties of the deposits underlying the Huntington-Smithtown area, Suffolk County, N.Y__-________-_--____----_-----_--------_-_- 16 3. Estimated permeability of water-bearing material in the Mag- othy (?) formation and Pleistocene deposits ________________ 19 4. Summary of average discharge of streams continuously or occa­ sionally gaged by the U.S. Geological Survey in the Hunting­ ton-Smithtown area.. -____-_-__--_--_-----_------_-____ 50 5. Chemical analyses of water from typical wells in the Hunting­ ton-Smithtown area _________-_____-___-_-__-__---_--!___ 50 6. Iron concentration, chloride concentration, hardness in CapOg and variation in pH of ground water in the Huntington- Smithtown area, 1956-59______________________________ 51 7. Records of selected wells in the Huntington-Smithtown area... 60 CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES HYDROGEOLOGY OF THE HUNTINGTON-SMITHTOWN AREA, SUFFOLK COUNTY, NEW YORK By E. K. LUBKE ABSTRACT This report presents the results of an investigation of the ground-water resources and related geologic environment of the Huntington-Smithtown area, New York, by the U.S. Geological Survey in cooperation with the Suffolk County Board of Supervisors, the Suffolk County Water Authority, and the New York State Water Resources Commission. Fieldwork on the investi­ gation, which is part of an overall program for the continuing appraisal of the ground-water reservoir of Long Island, N.Y., was carried on between November 1957 and May 1959. The Huntington-Smithtown area contains about 153 square miles in north­ western Suffolk County, and the population in 1958 was estimated to be 153,000. The area is in north-central Long Island, which is the partly sub­ merged northeastern extension of the Atlantic Coastal Plain. The chief physiographic features, which are largely of glacial origin, include a belt of headlands and bays along the margin of Long Island Sound, the Harbor Hill end moraine, an intermorainal belt, the Ronkonkoma terminal moraine and related clusters of hills, and a south-sloping glacial outwash plain. All the larger streams, such as the Nissequogue River, Cold Spring Brook, Sunken Meadow Creek, Stony Hollow Run, and Mill Creek, are perennial and are characterized by markedly uniform flow sustained by ground-water dis­ charge. The total runoff of these streams has averaged about 11 billion gallons a year during the period of record. The climate is temperate humid with an annual average precipitation of 49 inches. Since World War II, a large growth in population has taken place in the report area, which is sub­ urban to New York City. Concurrently, many new homes have been constructed and light industries have been established. Agriculture, formerly a major activity, is on the wane with the inroads of suburban development on farmed acreage. In 1960, less than 1,800 acres was farmed. The Huntington-Smithtown area is underlain by 400 to 1,300 feet of uncon- solidated deposits of Cretaceous and Quaternary age resting upon a south­ east-sloping bedrock surface. These deposits constitute the ground-water reservoir. Three distinct aquifers have been recognized in the ground-water reservoir. These are: (1) a shallow aquifer, which mainly includes perme­ able upper Pleistocene deposits, the Magothy(?) formation, and possibly some Pliocene deposits; it lies between the water table and about 50 to 80 feet below sea level and contains water generally under unconfined conditions, Dl D2 CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATES (2) an intermediate aquifer, which extends from about 60 to 100 feet below sea level to 850 feet below sea level in the Pleistocene deposits and in the Magothy(?) formation and which contains water under confined conditions, (3) a deep aquifer, which is mainly composed of the Lloyd sand member of the Raritan formation and which contains water under confined conditions. In 1957, approximately 53 percent of the gross pumpage was from Pleistocene deposits, 44 percent from the Magothy(?) formation, and 3 percent from the. Lloyd sand member.. The average natural recharge to the ground-water reservoir in the Hunt- ington-Smithtown area is estimated to be 147 mgd (million gallons per day). This is equivalent to an average of about 43 percent of the average annual precipitation (49 inches) or 21 inches of water. The remainder of the pre­ cipitation is returned to the atmosphere by evapotranspiration or is lost to the sea by overland runoff. In general, ground-water supplies in substantial quantity and of good qual­ ity can be obtained from wells almost everywhere in the project area, except locally on Lloyd and Eaton Necks. Between 1932 and 1957, average with­ drawals for public supply increased from 1.5 mgd in 1932 to 8.8 mgd in 1957. In addition, about 5.9 mgd was used in 1957 for industrial, institutional, domestic, and agricultural purposes. On Lloyd and Batons Necks, potentialities for ground-water development are limited by a reduced thickness of the ground-water reservoir and the nearness of salt-water bodies, which pose the ever-present threat of contami­ nation. In this regard, Batons Neck is particularly vulnerable,