USGS Water-Year Summary 2023
11293350 Union Reservoir near Big Meadows, CA
LOCATION - Lat 38°25'50", long 119°59'47" referenced to North American Datum of 1927, Alpine County, CA, Hydrologic Unit 18040010, unsurveyed, in Stanislaus National Forest, at outlet structure on upstream face of Union Dam on North Fork Stanislaus River, and 6.4 mi east of Big Meadows.
DRAINAGE AREA - 13.8 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - October 1986 to July 2006 (instantaneous observations), July 2006 to September 2010 (seasonal), October 2011 to current year. Unpublished records for water years 1981-86 available in files of the U.S. Geological Survey.
GAGE - Water-stage recorder since July 12, 2006. Datum of gage is 6,823.4 ft above NGVD of 1929 (levels by Pacific Gas and Electric Company).
COOPERATION - Records were collected by the Northern California Power Association, under general supervision of the U.S. Geological Survey, in connection with Federal Energy Regulatory Commission project no. 11563.
EXTREMES FOR PERIOD OF RECORD - Maximum contents since 2011, 3,290 acre-ft, Jan. 8, 2017, gage height, 27.73 ft; minimum, 456 acre-ft, Jan. 29, 2014, gage height, 11.05 ft.