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Water-Year Summary for Site 11441001

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Available Parameters
00054 Reservoir storage(Obs.)  

Water year 2023: 2022-10-01 to 2023-09-30
 
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USGS Water-Year Summary 2023
11441001 Union Valley Reservoir near Riverton, CA
LOCATION - Lat 38°51'49", long 120°26'15" referenced to North American Datum of 1927, in NW 1/4 NW 1/4 sec.29, T.12 N., R.14 E., El Dorado County, CA, Hydrologic Unit 18020129, Eldorado National Forest, in valve control house near left bank at Union Valley Dam on Silver Creek, 0.7 mi upstream from Little Silver Creek, and 6.6 mi north of Riverton.
DRAINAGE AREA - 83.7 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - October 1962 to current year.
CHEMICAL ANALYSES: Water year 1996.
GAGE - Water-stage recorder. Datum of gage is NGVD of 1929 (levels by Sacramento Municipal Utility District).
COOPERATION - Records were collected by Sacramento Municipal Utility District, under general supervision of the U.S. Geological Survey, in connection with Federal Energy Regulatory Commission project no. 2101.
REMARKS - Reservoir is formed by earthfill dam completed in December 1962; storage began May 1962. Contents based on capacity table dated May 2000. Usable capacity, 266,389 acre-ft, between elevations 4,645.0 ft, minimum operating level, and 4,870.0 ft, top of radial spillway gates. Dead storage, 2,888 ac-ft. Reservoir receives water from the South Fork Rubicon River via Robbs Peak Powerplant (station 11429300) and from South Fork Silver Creek, since April 1985, via Jones Fork Powerplant (station 11440900). Water is used for power development in the South Fork American River Basin. Records, including extremes, represent total contents at 2400 hours. See schematic diagrams of Middle Fork American and Rubicon River Basins and South Fork American River Basin available from the California Water Science Center.
EXTREMES FOR PERIOD OF RECORD - Maximum contents, 279,100 acre-ft, July 9, 1974, elevation, 4,870.6 ft; minimum since reservoir first filled, 18,300 acre-ft, Jan. 13, 1977, elevation, 4,683.3 ft.