LOCATION.--Lat 41°02'35.5", long 73°53'45.8" referenced to North American Datum of 1983, Rockland County, NY, Hydrologic Unit 02030101, on right bank on upstream landward facing section of concrete pier, at east end of Ferry Road, 1.3 mi east of Piermont, and 24.9 mi north of the Battery.
DRAINAGE AREA.--13,125 mi².
PERIOD OF RECORD.--November 2010 to February 2012, June 2013 to current year.
GAGE.--Water-stage recorder. Datum of gage is NGVD of 1929 (New York State Department of Transportation bench mark). To convert elevations to NAVD of 1988, subtract 1.06 ft.
REMARKS.--Elevations are not corrected for changes in water density. Blanks in tables are the result of only one high or low tide during a day or interruption of record.
EXTREMES FOR PERIOD OF RECORD.--Maximum elevation, 7.40 ft, Aug. 28, 2011; minimum elevation, -4.00 ft, Jan. 6, 2018.
EXTREMES OUTSIDE PERIOD OF RECORD.--Flood of Oct. 29, 2012, reached an elevation of 10.68 ft, from floodmark.
PERIOD OF DAILY RECORD¹.--SPECIFIC CONDUCTANCE: November 2010 to February 2012, July 2013 to September 2015.
WATER TEMPERATURE: November 2010 to February 2012, July 2013 to September 2015.
INSTRUMENTATION¹.--Water-temperature and specific-conductance satellite telemeter provides 15-minute-interval readings.
EXTREMES FOR PERIOD OF DAILY RECORD¹.--SPECIFIC CONDUCTANCE: Maximum, 27,200 uS/cm at 25 °C, Sept. 29, 2013; minimum, 183 uS/cm at 25 °C, Apr. 30, 2011.
WATER TEMPERATURE: Maximum, 31.1 °C, July 22, 2011, July 18, 2013; minimum, -0.6 °C, Jan. 21, 23, 24, Feb. 3, 2011.
¹ Water-Quality Records

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Peak Flow and Stage Information

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 1.00 ft. To convert data to MHHW datum subtract 3.07 ft. To convert data to MLLW datum add 0.90 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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