LOCATION.--Lat 40°37'39", long 73°34'33" referenced to North American Datum of 1927, Nassau County, NY, Hydrologic Unit 02030202, at Town of Hempstead Guy Lombardo Marina, in Freeport.
PERIOD OF RECORD.--October 1999 to current year. January 1975 to November 1993, in files of Town of Hempstead Department of Conservation & Waterways.
GAGE.--Water-stage recorder. Datum of gage is NGVD of 1929. January 1975 to November 1993, water-stage recorder at site 1,100 ft west.
REMARKS.--ELEVATION WY 2013: Records excellent, except those for Oct. 29, Dec. 10-21, 25-29, Jan. 6-19, 22-31, Feb. 2-17, 20, Feb. 22, to Mar. 4, Mar. 6-12 and Aug. 2, which are good. Satellite and telephone elevation telemeters at station.
EXTREMES FOR PERIOD OF RECORD.--Maximum 10.15 ft, Oct. 29, 2012; Minimum -3.86 ft, Feb. 11, 2001.
EXTREMES OUTSIDE PERIOD OF RECORD.--Storm tides of Oct. 31, 1991 and Dec. 11, 1992, reached elevations of 7.0 and 7.2 ft, respectively, from information provided by Town of Hempstead Department of Conservation & Waterways. Minimum elevation recorded, -4.4 ft, Mar. 16, 1980, from information provided by Town of Hempstead Department of Conservation & Waterways.

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NAVD 1988 Datum Conversion Information

Elevation observations and tidal predictions for this station are reported to NGVD 1929. To convert data to NAVD 1988 subtract 1.14 ft. To convert data to MHHW datum subtract 3.30 ft. To convert data to MLLW datum add 1.20 ft. These corrections vary from site to site.

NGVD 1929 is the National Geodetic Vertical Datum of 1929, formerly called "mean sea level" or "Sea Level Datum of 1929." NGVD 1929 was a general adjustment of the first-order level nets fit to mean sea level at 26 tide gages in the US and Canada. NAVD 1988 is the North American Vertical Datum of 1988, which is a geodetic datum derived from a general adjustment of the first-order level nets fit to 1 tide gage in eastern Canada. MHHW is mean higher high water, which is a site-specific datum determined by averaging the highest of the 2 high tides that occur each day over a 19-year tidal epoch. For tide gages with less than 19 years of record, this datum is estimated by correlation with long-term tide gages. MLLW is mean lower low water, which is a site-specific datum determined by averaging the lowest of the 2 low tides that occur each day over a 19-year tidal epoch. For tide gages with less than 19 years of record, this datum is estimated by correlation with long-term tide gages.

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