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Click for larger image 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.
DRAINAGE AREA.--11,560 mi2.
  • WSP 726: Drainage area.
  • WDR MD-DE-75-1: 1973-74(M).
  • https://waterdata.usgs.gov/nwis/dv/?site_no=01646500: 2018.
  • https://waterdata.usgs.gov/nwis/uv/?site_no=01646500: 2021.
  • Discharge for Measurement 385 made on 06/25/2021 was revised on 09/22/2021 due to an error in computation.
PERIOD OF RECORD.--March 1930 to current year.
GAGE.--Water-stage recorder, crest-stage gage, and concrete control. Datum of gage is 37.20 ft above North American Vertical Datum of 1988. Prior to Jun 7, 1930, nonrecording gage, and June 7, 1930 to Jan. 22, 1965, water-stage recorder at site 1 mi upstream on right bank at same gage datum.
REMARKS.--Diversions since June 1959. U.S. Geological Survey satellite data-collection platform at station.
EXTREMES OUTSIDE PERIOD OF RECORD.--Flood of June 2, 1889, was of approximately the same magnitude as that of March 19, 1936.
COOPERATION.--Funding for the operation of this station is provided by the U.S. Geological Survey. Access to gage site provided by the Baltimore District, U.S. Army Corps of Engineers.
Boating safety tips
This station managed by the MD-DE-DC Water Science Center Baltimore office.

Available Parameters Available Period
2019-07-24  2021-10-23
2007-10-01  2019-10-01
2007-10-01  2019-10-01
2007-10-01  2019-10-01
2013-11-23  2019-05-27
1972-06-09  2021-10-23
2007-10-01  2021-10-23
2019-07-24  2021-10-23
2007-10-01  2019-10-01
2013-11-23  2019-05-27
2019-07-24  2021-10-23
2013-11-23  2019-05-27
2019-07-24  2021-10-23
2013-11-23  2019-05-27
2019-07-24  2021-10-23
2013-11-23  2019-05-27
2019-07-24  2021-10-23
2011-12-03  2019-06-11


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Summary of all available data for this site
Instantaneous-data availability statement

Discharge, cubic feet per second

Most recent instantaneous value: 3020 10-23-2021   02:45 EDT
* Records for these data have been revised
Graph of  Discharge, cubic feet per second

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