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USGS Water-Year Summary 2024
11289650 Tuolumne River below La Grange Dam, near La Grange, CA
LOCATION - Lat 37°39'59", long 120°26'28" referenced to North American Datum of 1927, in NW 1/4 NW 1/4 sec.21, T.3 S., R.14 E., Stanislaus County, CA, Hydrologic Unit 18040009, on left bank, 0.5 mi downstream from La Grange Dam, and 1.1 mi east of La Grange.
DRAINAGE AREA - 1,538 mi².
REVISIONS HISTORY - See Time-series Revision Statements.
SURFACE-WATER RECORDS
PERIOD OF RECORD - October 1970 to current year.
GAGE - Water-stage recorder and crest-stage gage. Datum of gage is 170.19 ft above NGVD of 1929 and 172.60 ft above NAVD of 1988.
REMARKS - Flow diverted into Modesto Canal (station 11289000) and Turlock Canal (station 11289500) at La Grange Dam. Flow regulated by Don Pedro Powerplant, Don Pedro Reservoir (station 11287500), 4.5 mi upstream, Hetch Hetchy Reservoir (station 11275500), Cherry Lake (station 11277200), and Lake Eleanor (station 11277500). Tuolumne Canal (station 11297500) diverts water from the Stanislaus River Basin into the Tuolumne River Basin upstream from station. Diversion through Hetch Hetchy Aqueduct to San Francisco began Oct. 19, 1934. For records of combined discharge of river and Modesto and Turlock Canals, see station 11289651. See schematic diagram of Tuolumne River Basin available from the California Water Science Center.
EXTREMES FOR PERIOD OF RECORD - River only, maximum discharge, 58,900 ft³/s, Jan. 3, 1997, gage height, 28.43 ft; no flow for several days during September and October 1977.
Combined flow, maximum daily discharge, 50,100 ft³/s, Jan. 3, 1997; minimum daily, 0.45 ft³/s, Nov. 2, 1970.
WATER-QUALITY RECORDS
PERIOD OF RECORD -
CONTINUOUS WATER-QUALITY DATA:
WATER TEMPERATURE: Water years November 1970 to current year. (water years 1970-2023, daily).
INSTRUMENTATION - Thermistor equipped water-quality recorder since November 1970.
REMARKS - Water temperature can be affected by releases from La Grange Dam.
