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Water-Table and Potentiometric-Surface Altitudes in the Upper Glacial, Magothy, and Lloyd Aquifers beneath Long Island, New York, March-April 2006

Scientific Investigations Map 3066

Prepared in cooperation with the Nassau County Department of Public Works, New York City Department of Environmental Protection, New York City Department of Environmental Conservation, Suffolk County Department of Health Services, Suffolk County Water Authority, Town of East Hampton, Town of North Hempstead, Town of Shelter Island, Town of South Hampton, and the U.S. Environmental Protection Agency
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Abstract

The U.S. Geological Survey (USGS), in cooperation with State and local agencies, systematically collects ground-water data at varying measurement frequencies to monitor the hydrologic situation on Long Island, New York. Each year during March and April, the USGS conducts a synoptic survey of hydrologic conditions to define the spatial distribution of the water table and potentiometric surfaces within the three main water-bearing units underlying Long Island - the upper glacial, Magothy, and Lloyd aquifers. These data and the maps constructed from them are commonly used in studies of Long Island's hydrology, and by water managers and suppliers for aquifer management and planning purposes. Water-level measurements made in 502 wells across Long Island during March-April 2006, were used to prepare the maps in this report. Measurements were made by the wetted-tape method to the nearest hundredth of a foot. Water-table and potentiometric-surface altitudes in these aquifers were contoured using these measurements. The water-table contours were interpreted using water-level data collected from 341 wells screened in the upper glacial aquifer and (or) shallow Magothy aquifer; the Magothy aquifer's potentiometric-surface contours were interpreted from measurements at 102 wells screened in the middle to deep Magothy aquifer and (or) contiguous and hydraulically connected Jameco aquifer; and the Lloyd aquifer's potentiometric-surface contours were interpreted from measurements at 59 wells screened in the Lloyd aquifer or contiguous and hydraulically connected North Shore aquifer. Many of the supply wells are in continuous operation and, therefore, were turned off for a minimum of 24 hours before measurements were made so that the water levels in the wells could recover to the level of the potentiometric head in the surrounding aquifer. Full recovery time at some of these supply wells can exceed 24 hours; therefore, water levels measured at these wells are assumed to be less accurate than those measured at observation wells, which are not pumped. In this report, all water-level altitudes are referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).

Geospatial Extents

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Water-Table and Potentiometric-Surface Altitudes in the Upper Glacial, Magothy, and Lloyd Aquifers beneath Long Island, New York, March-April 2006
Series title:
Scientific Investigations Map
Series number:
3066
Edition:
-
Year Published:
2009
Language:
ENGLISH
Publisher:
U.S. Geological Survey
Contributing office(s):
New York Water Science Center
Description:
4 Map Sheets: each 72 x 34 inches
Time Range Start:
2006-03-01
Time Range End:
2006-04-30
Projection:
Lambert Conformal Conic
Scale:
25000
Online Only (Y/N):
Y
Additional Online Files(Y/N):
Y