LOCATION.--Lat 40°51'24.8", long
73°42'05.3" referenced to North American Datum of
1983, Nassau County, NY, Hydrologic Unit 02030201, at Helen
Keller National Center for Deaf-Blind Youths and Adults, 300 ft
north of Middle Neck Road, westernmost well, Sands Point.
WELL CHARACTERISTICS.--Depth 396 ft. Upper casing
diameter 6 in; top of first opening 378 ft, bottom of last
opening 388 ft. Datum of gage is NGVD of 1929.
DATUM.--Land-surface datum is 100.9 ft above National
Geodetic Vertical Datum of 1929. Measuring point: Top of
casing, 1.32 ft above land-surface datum, 102.22 ft above
National Geodetic Vertical Datum of 1929, Jan. 25, 1977 to Jul.
8, 2015; Top of casing at base of shelter 1.32 ft above land
surface, 102.22 ft above National Geodetic Vertical Datum of
1929, Jul. 7, 2015 to present.
PERIOD OF RECORD.--December 1960 to January 2000,
January 2002 to current year. Unpublished records for August
1957 to September 1975 are available in the files of the U.S.
Geological Survey.
GAGE.--Water-level recorder installed January 2003;
15-minute recording interval. Periodic manual measurements made
by USGS personnel.
REMARKS.--Water level affected by tidal fluctuation and
nearby pumping. Cellular water-level telemeter at
station.
EXTREMES FOR PERIOD OF RECORD.--Highest water level
recorded, 11.87 ft above NGVD of 1929, Feb. 28, 2020; lowest
recorded, 50.36 ft below NGVD of 1929, Aug. 27, 2016.
Daily data pages will be decommissioned in early 2026.
Daily data are now available in WDFN.
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