Long Island’s aquifer system consists of a seaward-dipping wedge of mostly unconsolidated stratified sediments comprised of sand, gravel, silt and clay.
The uppermost aquifer is called the “upper glacial Aquifer”, and is comprised of Pleistocene outwash and ice-contact deposits. Beneath the upper glacial lies the Cretaceous Magothy aquifer, a regional Atlantic coastal plain aquifer that stretches from Long Island, to New Jersey to Maryland. Most of Long Island’s public water supplies come from the Magothy aquifer. Beneath the Magothy aquifer is the Cretaceous Lloyd Aquifer, which is separated from the overlying Magothy aquifer by the Raritan clay, which is a confining unit. A minor aquifer, known as the Jameco Aquifer, is a Pleistocene sand and gravel aquifer that occurs in southern Kings and Queens Counties, and extreme southwestern Nassau County (McLymonds and Franke, 1972). The aquifers beneath Long Island are major sources of water for public and domestic supply and serve as a vital source of freshwater for industrial and agricultural uses throughout the region.
Surface altitudes of hydrogeologic units are depicted in a USGS Hydrologic Atlas HA-709 (Smolensky and others, 1989), which shows the hydrogeologic framework of Long Island in a series of 1:125,000-scale maps and geologic sections.
In addition to the three main aquifers listed, there are several localized aquifers and confining units that have been the subject of separate studies by the USGS. Some of the more recent USGS studies of these minor hydrogeologic units include the Smithtown Clay, which is an inter-morainale clay (Krulikas and Koszalka, 1983) and the Twenty Foot Clay along the south shore of Long Island (Doriski 1983). More recent investigations redefining the hydrogeologic framework are along the northern shore of Nassau County by Stumm and others (2001, 2002, 2004), have provided newly interpreted hydrogeologic units of Pleistocene age. These hydrogeologic units are called the North Shore aquifer and North Shore confining unit.
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Table of Contents
State of the Aquifer, Long Island, New York - Introduction
- Precipitation
- NWIS - the USGS Data Archive
- Surface Water - Streamflow
- Groundwater Levels
- Water Table and Surface Maps
- Water Use
- Groundwater Budget
- Inflow to the Groundwater System
- Outflow from the Groundwater System
Below are other science projects associated with this project.
Hydrologic Cycle
Long Island Precipitation and Recharge
Long Island Surface Water
Long Island Groundwater
Long Island Fresh and Saltwater Relations/Interactions
- Overview
Long Island’s aquifer system consists of a seaward-dipping wedge of mostly unconsolidated stratified sediments comprised of sand, gravel, silt and clay.
The uppermost aquifer is called the “upper glacial Aquifer”, and is comprised of Pleistocene outwash and ice-contact deposits. Beneath the upper glacial lies the Cretaceous Magothy aquifer, a regional Atlantic coastal plain aquifer that stretches from Long Island, to New Jersey to Maryland. Most of Long Island’s public water supplies come from the Magothy aquifer. Beneath the Magothy aquifer is the Cretaceous Lloyd Aquifer, which is separated from the overlying Magothy aquifer by the Raritan clay, which is a confining unit. A minor aquifer, known as the Jameco Aquifer, is a Pleistocene sand and gravel aquifer that occurs in southern Kings and Queens Counties, and extreme southwestern Nassau County (McLymonds and Franke, 1972). The aquifers beneath Long Island are major sources of water for public and domestic supply and serve as a vital source of freshwater for industrial and agricultural uses throughout the region.
Surface altitudes of hydrogeologic units are depicted in a USGS Hydrologic Atlas HA-709 (Smolensky and others, 1989), which shows the hydrogeologic framework of Long Island in a series of 1:125,000-scale maps and geologic sections.
In addition to the three main aquifers listed, there are several localized aquifers and confining units that have been the subject of separate studies by the USGS. Some of the more recent USGS studies of these minor hydrogeologic units include the Smithtown Clay, which is an inter-morainale clay (Krulikas and Koszalka, 1983) and the Twenty Foot Clay along the south shore of Long Island (Doriski 1983). More recent investigations redefining the hydrogeologic framework are along the northern shore of Nassau County by Stumm and others (2001, 2002, 2004), have provided newly interpreted hydrogeologic units of Pleistocene age. These hydrogeologic units are called the North Shore aquifer and North Shore confining unit.
Sources/Usage: Public Domain.Figure 13. Generalized cross section of Long Island showing the main aquifers and confining units (Cohen and others, 1968)(Public domain.) _______________________________
Table of Contents
State of the Aquifer, Long Island, New York - Introduction
- Precipitation
- NWIS - the USGS Data Archive
- Surface Water - Streamflow
- Groundwater Levels
- Water Table and Surface Maps
- Water Use
- Groundwater Budget
- Inflow to the Groundwater System
- Outflow from the Groundwater System
- Science
Below are other science projects associated with this project.
Hydrologic Cycle
The water cycle has no starting point, but we'll begin in the oceans, since that is where most of Earth's water exists. The sun, which drives the water cycle, heats water in the oceans. Some of it evaporates as vapor into the air; a relatively smaller amount of moisture is added as ice and snow sublimate directly from the solid state into vapor. Rising air currents take the vapor up into the...Long Island Precipitation and Recharge
Precipitation is water released from clouds in the form of rain, freezing rain, sleet, snow, or hail. It is the primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth. Most precipitation falls as rain. Water seeping down from the land surface and reaching the water table adds to the groundwater and is called groundwater recharge. Groundwater is...Long Island Surface Water
Streams either gain water from inflow of groundwater from the underlying aquifer or lose water by outflow to the underlying aquifer. Many streams do both, gaining in some reaches and losing in other reaches. Furthermore, the groundwater flow directions near any given stream can change seasonally as the altitude of the water table changes with respect to the stream-surface altitude or when rapid...Long Island Groundwater
Approximately 30% of the world’s water is stored as groundwater. Groundwater moves very slowly, on the order of feet per day, however it is still part of the hydrologic cycle. Most of the water in the ground comes from precipitation that infiltrates downward from the land surface.Long Island Fresh and Saltwater Relations/Interactions
Because saltwater has a greater density than freshwater, fresh groundwater in coastal aquifers will overlie any saltwater that is present in the aquifer at depth (Figure 14).