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LOCATION.--Lat 40°53'18.8", long 73°38'16.8" referenced to North American Datum of 1983, Nassau County, NY, Hydrologic Unit 02030201, on southern shore at Nassau County Welwyn Preserve, at Glen Cove.
Elevation observations and tidal predictions for this station are reported to NGVD 1929. To convert data to NAVD 1988 subtract 1.09 ft. To convert data to MHHW datum subtract 4.82 ft. These corrections vary from site to site.
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.
Additional sensor graph(s) available (click on graph or sensor name)
Water elevation, astronomical-tide elevation, and residual water level Graph updated every 15 minutes