Introduction | Location and Physical Setting | Freshwater | State of the Aquifer System | Interactive Content | References


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 When large amounts of water are withdrawn from the ground, however, the water table is locally depressed and can reduce the amount of ground water that discharges to streams and salt-water bays.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.