USGS Water-Year Summary 2024
404030073293703 N 180. 2
Northern Atlantic Coastal Plain aquifer system
Magothy Aquifer
LOCATION - Lat 40°40'30", long 73°29'37" referenced to North American Datum of 1927, Nassau County, NY, Hydrologic Unit 02030202, at Long Island Railroad track embankment, 200 ft north of Sunrise Highway (State Route 27), west of Seaford-Oyster Bay Expressway (State Route 135), Seaford.
GROUNDWATER RECORDS
WELL CHARACTERISTICS - Depth 723 ft. Upper casing diameter 4 in; top of first opening undefined, bottom of last opening undefined. Screen assumed at bottom. Datum of gage is NGVD of 1929.
DATUM - Land-surface datum is 16 ft above National Geodetic Vertical Datum of 1929. Measuring point: Top of coupling, 13.69 ft above land-surface datum, 29.69 ft above land-surface datum, Jun. 6, 1952 to Jul. 17, 2015; Top of steel 4 inch casing, 29.4 ft above land-surface datum, Jul. 17, 2015 to Jul. 18, 2017; Top of 4 inch blue insert that holds OTT, 29.44 ft above land-surface datum, Jul. 18, 2017 to present.
PERIOD OF RECORD - June 1952, April 1957 to current year.
GAGE - Water-level recorder installed October 2007 to present; 15-minute recording interval. Periodic manual measurements made by USGS personnel.
EXTREMES FOR PERIOD OF RECORD - Highest water level measured, 21.08 ft above NGVD of 1929, June 6, 1952; lowest recorded, 7.97 ft above NGVD of 1929, Aug. 28, 2016.