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Water-Year Summary for Site 11234700

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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
11234700 Mammoth Pool Reservoir near Big Creek, CA
LOCATION - Lat 37°19'40", long 119°19'38" referenced to North American Datum of 1927, in SE 1/4 SE 1/4 sec.10, T.7 S., R.24 E., Madera County, CA, Hydrologic Unit 18040006, in Sierra National Forest, in gatehouse of power tunnel intake, 0.7 mi northwest of dam on San Joaquin River, and 9.0 mi northwest of town of Big Creek.
DRAINAGE AREA - 995 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - October 1959 to current year.
GAGE - Water-stage recorder. Elevation of gage is 3,354.28 ft above NGVD of 1929 (levels by Southern California Edison Co.).
COOPERATION - Records were collected by Southern California Edison Co., under general supervision of the U.S. Geological Survey, in connection with Federal Energy Regulatory Commission project no. 2085. Records not rounded to U.S. Geological Survey standards.
REMARKS - Reservoir is formed by an earth-fill dam; storage began Oct. 8, 1959. Contents based on capacity table dated Nov. 6, 1959. Usable capacity, 119,940 acre-ft, between elevations 3,100.00 ft, invert of power tunnel, and 3,330.00 ft, crest of spillway. Additional storage of 2,780 acre-ft is not available for release. Water is diverted from Mammoth Pool through tunnel for power development and returned to river 8.5 mi downstream from dam. Records, excluding extremes, represent usable contents at 2400 hours. See schematic diagram of lower San Joaquin River Basin available from the California Water Science Center.
EXTREMES FOR PERIOD OF RECORD - Maximum contents, 128,944 acre-ft, Jan. 2, 1997, elevation, 3,338.00 ft; minimum contents since appreciable storage was attained, 1,134 acre-ft, Sept. 25, 1992, elevation, 3,112.82 ft.