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Scientific Investigations Map 3270

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

Water-Table and Potentiometric-Surface Altitudes in the Upper Glacial, Magothy, and Lloyd Aquifers beneath Long Island, New York, April-May 2010

By Jack Monti, Jr., Michael Como, and Ronald Busciolano

Sheet 1 - Water table
     Sheet 1 - Water table
Sheet 2 - Potentiometric surface in the Magothy and Jameco aquifers
     Sheet 2 - Potentiometric surface in
     the Magothy and Jameco aquifers
Sheet 3 - Potentiometric surface in the Lloyd and North Shore aquifers
     Sheet 3 - Potentiometric surface in
     the Lloyd and North Shore aquifers
Sheet 4 - Depth to water table
     Sheet 4 - Depth to water table

Introduction

The U.S. Geological Survey (USGS), in cooperation with State and local agencies, systematically collects groundwater data at varying measurement frequencies to monitor the hydrologic conditions on Long Island, New York. Each year during  April and May, the USGS conducts a synoptic survey of water levels 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 (Smolensky and others, 1989)—and the hydraulically connected Jameco (Soren, 1971) and North Shore aquifers (Stumm, 2001). These data and the maps constructed from them are commonly used in studies of Long Island’s hydrology and are used by water managers and suppliers for aquifer management and planning purposes.

Water-level measurements made in 503 monitoring wells, a network of observation and supply wells, and 16 streamgage locations across Long Island during April–May 2010 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 by using these measurements. The water-table contours were interpreted by using water-level data collected from 16 streamgages, 349 observation wells, and 1 supply well screened in the upper glacial aquifer and (or) shallow Magothy aquifer; the Magothy aquifer’s potentiometric-surface contours were interpreted from measurements at 67 observation wells and 27 supply wells screened in the middle to deep Magothy aquifer and (or) the contiguous and hydraulically connected Jameco aquifer. The Lloyd aquifer’s potentiometric-surface contours were interpreted from measurements at 55 observation wells and 4 supply wells screened in the Lloyd aquifer or the 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 (Busciolano, 2002). In this report, all water-level altitudes are referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).

Hydrographs are included on these maps for selected wells that are instrumented with recording equipment. These hydrographs are representative of the 2010 water year to show the changes that have occurred throughout that period. The synoptic survey water level measured at the well is included on each hydrograph.

First posted November 18, 2013

  • Sheet 4 (Depth to water table) PDF
    68" X 22" Print size (21.3 MB)


    Files are not 508 compliant. For further information, contact the New York Water Science Center Director.

For additional information, contact:
Director, New York Water Science Center
U.S. Geological Survey
425 Jordan Road
Troy, NY 12180
(518) 285-5600
http://ny.water.usgs.gov

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Suggested citation:

Monti, Jack, Jr., Como, Michael, and Busciolano, Ronald, 2013, Water-table and Potentiometric-surface altitudes in the Upper Glacial, Magothy, and Lloyd aquifers beneath Long Island, New York, April-May 2010: U.S. Geological Survey, Scientific Investigations Map 3270, 4 sheets, scale 1:125,000, https://dx.doi.org/10.3133/sim3270.

ISSN 2329-132X (online)



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