Geospatial Dataset of Water-Table and Potentiometric-Surface Altitudes in the Upper Glacial, Magothy, and Lloyd Aquifers of Long Island, New York, April-May 2013

Dates

Start Date: 2013-04-01
End Date: 2013-05-31
Publication Date: 2022-11-17

Citation

Como, M.D., Finkelstein, J.S., Monti, Jack, Jr., and Busciolano, Ronald, 2022, Geospatial dataset of water-table and potentiometric-surface altitudes in the upper glacial, Magothy, and Lloyd Aquifers of Long Island, New York, April-May 2013: U.S. Geological Survey data release, http://doi.org/10.5066/F7RV0KSD.

Summary

The U.S. Geological Survey (USGS) is providing online maps of water-table and potentiometric-surface altitude in the upper glacial, Magothy, Jameco, Lloyd, and North Shore aquifers on Long Island, New York, April-May 2013. Also provided here, is a Depth-to-Water map for Long Island, NY, April-May 2013. USGS serves these maps and geospatial data as REST Open Map Services (as well as HTTP, JSON, KML, and shapefile), so end-users can use the maps and data on mobile and web clients. A companion report, U.S. Geological Survey Scientific Investigations Map 3326 (Como and others, 2015; http://dx.doi.org/10.3133/sim3326) further describes data collection and map preparation and presents 68x22 in. PDF versions, 4 sheets, scale 1:125,000. [...]

Summary

The U.S. Geological Survey (USGS) is providing online maps of water-table and potentiometric-surface altitude in the upper glacial, Magothy, Jameco, Lloyd, and North Shore aquifers on Long Island, New York, April-May 2013. Also provided here, is a Depth-to-Water map for Long Island, NY, April-May 2013. USGS serves these maps and geospatial data as REST Open Map Services (as well as HTTP, JSON, KML, and shapefile), so end-users can use the maps and data on mobile and web clients. A companion report, U.S. Geological Survey Scientific Investigations Map 3326 (Como and others, 2015; http://dx.doi.org/10.3133/sim3326) further describes data collection and map preparation and presents 68x22 in. PDF versions, 4 sheets, scale 1:125,000.

The U.S. Geological Survey, 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 (aquifers) 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 utilized by water managers and suppliers for aquifer management and planning purposes. Sheets 1-4 in U.S. Geological Survey Scientific Investigations Map 3326 (Como and others, 2015; http://dx.doi.org/10.3133/sim3326) were prepared using water-level data measured at 502 groundwater monitoring wells (observation and supply) and 16 streamgages across Long Island during April and May of 2013. Additionally, digital data sets were derived from the water-level observations that include 1) contour lines and a continuous raster of the depth to water table in the upper glacial and Magothy aquifers, 2) contour lines of the potentiometric surface in the middle to deep Magothy aquifer and the hydraulically connected Jameco aquifer, 3) contour lines of the potentiometric surface in the Lloyd aquifer and hydraulically connected North Shore aquifer, and 4) point feature classes for the 502 groundwater-monitoring wells and 16 streamgages where water levels were collected.

Data Sources

Water-level data measured at groundwater wells and streamgaging stations during April and May of 2013 were retrieved from the USGS National Water Information System (NWIS) database (http://waterdata.usgs.gov/nwis/si). Groundwater measurements were made using the wetted-tape method to the nearest hundredth of a foot. Supply wells were turned off for a minimum of 24 hours before measurements were made to allow the water levels in the wells to recover to ambient (non-pumping) conditions. 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 addition to pumping stresses, elevated chloride concentrations (saline water) also lower the water levels measured in certain wells. This reduction in water level is the result of saline water being denser than freshwater (Lusczynski, 1961). In this data release, all water-level altitudes are referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29).

Analysis

Contours of water-table and potentiometric-surface altitudes were created at a scale of 1:125,000 from the water-level data collected during the period of study. Water-table contours and a raster data set for the upper glacial and shallow Magothy aquifers were interpreted from water-level data collected at 334 observation wells, 1 supply well, and 16 streamgages; potentiometric-surface contours for the middle to deep Magothy aquifer and the hydraulically connected Jameco aquifer were interpreted from water-level data collected at 70 observation wells and 31 supply wells; and potentiometric-surface contours for the Lloyd aquifer and hydraulically connected North Shore aquifer were interpreted from water-level data collected at 58 observation wells and 8 supply wells. Editing of the geospatial data was conducted in ArcGIS Desktop (ESRI, 2015a) using geographic information system (GIS) tools.

Depth to water map

A GIS was used to create a continuous surface of the water table using an iterative finite-difference interpolation technique (ESRI, 2015b) with measurements from 334 observation wells, 1 supply well, 16 streamgages, interpreted 10-foot (ft) contour intervals, and the coastline.

A 10-meter digital-elevation model (DEM) was downloaded from The National Map portal (http://nationalmap.gov) and combined with additional land surface terrain models of Suffolk County and New York City, which were collected using Light Detection and Ranging (lidar) to produce a three-dimensional land-surface altitude model.

The continuous surface of the water table was adjusted for the vertical datum differences across Long Island. This surface was then subtracted from the topography at the same location. The results are shown as a continuous depth to water table map.

References Cited

Busciolano, Ronald, 2002, Water-table and potentiometric-surface altitudes of the Upper Glacial, Magothy, and Lloyd Aquifers on Long Island, New York, in March–April 2000, with a summary of hydrogeologic conditions: U.S. Geological Survey Water-Resources Investigations Report 01–4165, 17 p., 6 pl.

Como, M.D., Noll, M.L., Finkelstein, J.S., Monti, Jack, Jr., and Busciolano, Ronald, 2015, Water-table and potentiometric-surface altitudes in the Upper Glacial, Magothy, and Lloyd aquifers of Long Island, New York, April–May 2013: U.S. Geological Survey Scientific Investigations Map 3326, 4 sheets, scale 1:125,000, 6-p. pamphlet, http://dx.doi.org/10.3133/sim3326.

ESRI (Environmental Systems Resource Institute). 2015a. ArcMap 10.3.1. ESRI, Redlands, California.

ESRI (Environmental Systems Resource Institute). 2015b, Topo to Raster Tool, ESRI, Redlands, California.

Lusczynski, N.J., 1961, Head and flow of ground water of variable density: Journal of Geophysical Research, v. 66, no. 12, p. 4247-4256.

Smolensky, D.A., Buxton, H.T., and Shernoff, P.K., 1989, Hydrologic framework of Long Island, New York: U.S. Geological Survey Hydrologic Investigations Atlas HA–709, 3 sheets, scale 1:250,000.

Soren, Julian, 1971, Results of subsurface exploration in the mid-island area of western Suffolk County, Long Island, New York: Oakdale, N.Y., Suffolk County Water Authority, Long Island Resources Bulletin 1, 60 p.

Stumm, Frederick, 2001, Hydrogeology and extent of saltwater intrusion of the Great Neck peninsula, Great Neck, Long Island, New York: U.S. Geological Survey Water-Resources Investigations Report 99–4280, 41 p.

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Contacts

Author :: Michael D. Como, Jason S. Finkelstein, Jack Monti, Jr., Ronald Busciolano
USGS Mission Area :: Water Resources
SDC Data Owner :: New York Water Science Center
Distributor :: U.S. Geological Survey - ScienceBase

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Related External Resources

Type: PDF Download

Water-table and potentiometric-surface altitudes in the Upper Glacial, Magothy, and Lloyd aquifers of Long Island, New York, April-May 2013	http://dx.doi.org/10.3133/sim3326

Type: Mapping Application

Long Island Depth to Water and Hydrologic Conditions Viewer	https://experience.arcgis.com/experience/81dc041e5331461e942787bed9ce084b

Geospatial Dataset of Water-Table and Potentiometric-Surface Altitudes in the Upper Glacial, Magothy, and Lloyd Aquifers of Long Island, New York, April-May 2013

Dates

Citation

Summary