USGS Water-Year Summary 2020
01646502 POTOMAC RIVER (ADJUSTED) NEAR WASH, DC
LOCATION - Lat 38°56'59.2", long 77°07'39.5" referenced to North American Datum of 1983, Montgomery County, MD, Hydrologic Unit 02070008, on left bank just upstream from Little Falls Dam, 1 mi upstream from District of Columbia boundary line, 1.2 mi upstream from Chain Bridge, 1.8 mi east of Langley, Fairfax County, and at mile 117.4.
PERIOD OF RECORD - March 1930 to current year.
GAGE - Record includes computed discharge at 01646500 POTOMAC RIVER NEAR WASHINGTON, DC along with furnished records of diversions. Datum of gage is 37.20 ft above North American Vertical Datum of 1988.