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Water-Year Summary for Site 01644000

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  • Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
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Available Parameters
00060 Discharge(Mean)  

Water year 2022: 2022-10-01 to 2023-09-30

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USGS Water-Year Summary 2022
LOCATION - Lat 39°01'10", long 77°34'40" referenced to North American Datum of 1927, Loudoun County, VA, Hydrologic Unit 02070008, on left bank 400 ft upstream from bridge on State Highway 621 at Evergreen Mills, 1.4 mi downstream from Little River, 6.7 mi south of Leesburg, and 10.9 mi upstream from mouth.
DRAINAGE AREA - 332 mi².
REVISIONS HISTORY - WSP 851: 1935-37. WSP 951: 1933(M), 1937. WSP 1302: 1934-35(M). WSP 2103: Drainage area. WDR VA-72-1: 1937(M), 1943(M), 1951(M), 1956(M). WDR VA-79-1: 1978.
PERIOD OF RECORD - July 1909 to April 1911, September 1911 to December 1912, January 1930 to current year.
GAGE - Water-stage recorder. Datum of gage is 248.93 ft NGVD of 1929. July 12, 1909, to Dec. 31, 1912, nonrecording gage at site 1,000 ft downstream at different datum. Jan. 21, 1930 to Nov. 28, 1938, non-recording gage at site 400 ft downstream at datum of 244.73 ft NGVD of 1929.
COOPERATION - Records were provided by the Virginia Department of Environmental Quality - Water Division.
REMARKS - National Weather Service gage-height telemeter at station. Maximum discharge, 78,100 ft³/s, from rating curve extended above 11,000 ft³/s on basis of slope-area measurement of peak flow. Water-quality records for some prior periods have been collected at this location.
EXTREMES OUTSIDE PERIOD OF RECORD - Flood in May or June 1889 reached a stage of about 29 ft, discharge, about 45,000 ft³/s, site and datum in use 1930-38, from information by local residents.
EXTREMES FOR PERIOD OF RECORD - Instantaneous low flow, not determined, probably occurred Sept. 27-30, 1941.