USGS Water-Year Summary 2021
01647600 POTOMAC RIVER AT WISCONSIN AVE, WASHINGTON, DC
LOCATION - Lat 38°54'12.1", long 77°04'03.6" referenced to North American Datum of 1983, Washington, DC, Hydrologic Unit 02070010, on left bank at upstream end of Georgetown Waterfront Park, 0.60 mi upstream from mouth of Rock Creek, 0.08 mi downstream from Key Bridge, and at river mile 112.5.
DRAINAGE AREA - Not determined.
PERIOD OF RECORD - October 2009 to current year.
GAGE - Water stage recorder. Datum of gage is 0.00 ft above North American Vertical Datum of 1988 (NAVD88). Washington Mean Low Water Datum (WMLW) is +2.26 ft above NAVD88. Prior to October 1, 2013, datum of gage was 0.00 ft above National Geodetic Vertical Datum of 1929 (NGVD29).
EXTREMES OUTSIDE PERIOD OF RECORD - Maximum tidal gage height, 16.31 ft NGVD29 (17.72 ft WMLW), Oct. 17, 1942; Minimum unknown.
EXTREMES FOR PERIOD OF RECORD - Maximum elevation, 9.01 ft NGVD29, March 15, 2010; minimum elevation, unknown (stage dropped below minimum recordable level on Feb. 15, 2015).