State of the Aquifer, Long Island, New York

Science Center Objects

Groundwater is among the Nation's most important natural resources. Nationwide it provides half of our drinking water and is essential to the vitality of agriculture and industry, as well as to the health of rivers, wetlands, and estuaries throughout the country. On Long Island groundwater is the sole source of fresh water for over 2.6 million people.

The use of groundwater on Long Island for supply is affected by local geology and water quality. Natural groundwater discharge sustains the flow of streams, lakes, wetlands, and stabilizes the salinity of estuaries. When large amounts of water are withdrawn from the ground, however, the water table is locally depressed and can reduce the amount of ground water that discharges to streams and salt-water bays. Large-scale sewering practices have also reduced stream baseflow and discharge to salt-water bays. Therefore, water-supply strategies must evaluate the availability of groundwater by considering the corresponding effects of withdrawal on aquatic ecosystems. The suitability of groundwater for human consumption is determined by (1) the quality of water that recharges the aquifer system, (2) the presence of nearby potential sources of groundwater contamination, (3) the presence or absence of saltwater encroachment, and (4) the continual geochemical evolution of groundwater along flow paths.

The purpose of the State of the Long Island Aquifer System web page is to provide a web page devoted to Long Island groundwater resources. This web page gives background and conceptual information about the Long Island aquifer system and also gives a general description of groundwater conditions across Long Island. The tools and resources detailed in each section also include publication citations that guide users to further information.

This web page will be periodically updated to provide an online clearinghouse of Long Island groundwater resources to assist others in evaluating Long Island's groundwater system. As such, the web page gives a general synopsis of groundwater availability and suitability conditions across Long Island. An effort to quantify flow amounts under current (2005-2010) conditions are presented when available and selected case studies of groundwater contamination are shown for several different constituents.

Considerable information is available about the water resources of Long Island as a result of more than 100 years of research by the U.S. Geological Survey (USGS) in cooperation with many other Federal, State, and local partners. Much of this past research was designed to provide the information needed for specific water resource problems on Long Island. However, continued investigations of the islandwide hydrologic system, and the relations between the various components of the system, will help provide the information needed for continued management and stewardship of this important aquifer system.


Other References 

Burr, W.H., Hering, Rudolph, and Freeman, J.R., 1904, Report of the commission on additional water supply for the City of New York: New York, Martin B Brown, 980 p.

Cohen, Philip, Franke, O.L., and Foxworthy, B.L., 1968, An atlas of Long Island's water resources: U.S. Geological Survey Water Resources Commission Bulletin 62, 117 p.

Fry, J., Xian, G., Jin, S., Dewitz, J., Homer, C., Yang, L., Barnes, C., Herold, N., and Wickham, J., 2011. Completion of the 2006 National Land Cover Database for the Conterminous United States, PE&RS, Vol. 77(9):858-864.

Jacob, C.E., 1945, The water table in western and central parts of Long Island, New York: New York State Water Power and Control Commission Bulletin GW-12, 24 p.

Johnston, R. H., 1988, Factors affecting ground-water quality [abs.]: National water summary 1986; hydrologic events and ground-water quality: U.S. Geological Survey Water-Supply Paper 2325, p. 71-72.

Kimmel, G.E., 1971, The water-table on Long Island, New York, in March 1970: Suffolk County Department Environmental Control, Long Island Water Resources Bulletin 2, 8 p.

Kolpin, D. W.; Furlong, E. T.; Meyer, M. T.; Thurman, E. M.; Zaugg, S. D.; Barber, L. B.; Buxton, H. T., 2002, Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance: Environmental Science and Technology, 36 (6) 10 p.

Koszalka, E.J., 1975, The water table on Long Island, New York, in March 1974: Suffolk County Water Authority, Long Island Water Resources Bulletin. 5, 7 p.

Lusczynski, N.J., and Johnson, A.W., 1951, The water table in Long Island, New York in January 1951” New York State Water Power and Control Commission Bulletin GW-27, 28 p.

McMahon, Edward T., 1997, Stopping Sprawl by Growing Smarter: Planning Commissioners Journal, Number 26, Spring 1997, Burlington, VT.

Suter, Russell, 1937, Engineering report on the water supplies of Long Island: New York State Water Power and Control Commission Bulletin GW-2, 64 p.

T.C. Winter, J.W. Harvey, O.L. Franke, and W.M. Alley, 1998, Ground Water and Surface Water A Single Resource: U.S. Geological Survey Circular 1139, 79 p.

Westenbroek, S.M., Kelson, V.A., Dripps, W.R., Hunt, R.J., and Bradbury,K.R., 2010, SWB—A modified Thornthwaite-Mather Soil-Water-Balance code for estimating groundwater recharge: U.S. Geological Survey Techniques and Methods 6–A31, 60 p.


Table of Contents

State of the Aquifer, Long Island, New York - Introduction

Location and Physical Setting


  1. Hydrolgeologic Units
  2. Fresh and Saltwater Relations/Interactions

State of the Aquifer System

  1. Precipitation
  2. NWIS - the USGS Data Archive 
  3. Surface Water - Streamflow
  4. Groundwater Levels
  5. Water Table and Surface Maps
  6. Water Use
  7. Groundwater Budget
  8. Inflow to the Groundwater System
  9. Outflow from the Groundwater System
  1. Case Studies

Interactive Content