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Selected hydrogeologic and water-quality data from Jones Beach Island, Long Island, New York

Water-Resources Investigations Report 92-4171

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Abstract

A data-collection site was instrumented on Jones Beach Island, a barrier island south of Long Island, N.Y., to study local freshwater/ saltwater relations in the shallow ground-water system. A geologic test boring revealed about 88 feet of well-sorted glacial outwash sand above about 15 feet of Gardiners Clay, which directly overlies silty sand of the Magothy Formation. Tidal effects on water levels in Great South Bay, the upper glacial aquifer, and the Magothy aquifer were observed and quantified with a tidal gage in the bay and analog water-level recorders in the wells.Chloride concentrations in the upper Magothy aquifer were higher than expected--about 270 mg/L (milligrams per liter), and those in the upper glacial aquifer were 17,000 to 19,000 mg/L, about the same as in Great South Bay. Estimates of pressure and freshwater equivalent heads indicate that, at the data-collection site, freshwater is discharging upward from the Magothy aquifer into the salty upper glacial aquifer, but dilution by this freshwater is undetectable. The reason for the elevated chloride concentration in the Magothy aquifer cannot be determined from available hydrogeologic information.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Selected hydrogeologic and water-quality data from Jones Beach Island, Long Island, New York
Series title:
Water-Resources Investigations Report
Series number:
92-4171
Edition:
-
Year Published:
1995
Language:
ENGLISH
Publisher:
U.S. Dept. of the Interior, U.S. Geological Survey ; Earth Science Information Center, Open-File Reports Section [distributor],
Description:
iv, 21 p. :ill., maps ;28 cm.