USGS Water-Year Summary 2024

11276900 Tuolumne River below Early Intake, near Mather, CA

LOCATION - Lat 37°52'54", long 119°58'09" referenced to North American Datum of 1927, in NW 1/4 SW 1/4 sec.02, T.1 S., R.18 E., Tuolumne County, CA, Hydrologic Unit 18040009, in Stanislaus National Forest, on left bank, 0.6 mi upstream from Cherry Creek, 0.7 mi downstream from Robert C. Kirkwood Powerplant and Hetch Hetchy Aqueduct, and 6.3 mi west of Mather.

DRAINAGE AREA - 487 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD - October 1966 to current year.

GAGE - Water-stage recorder and crest-stage gage. Elevation of gage is 2,200 ft above NGVD of 1929, from topographic map.

REMARKS - Flow regulated by Hetch Hetchy Reservoir (station 11275500) 13 mi upstream and Robert C. Kirkwood Powerplant beginning Apr. 26, 1967. Water is diverted to Hetch Hetchy Aqueduct from the tailrace of the powerplant through a closed conduit. Flow in excess of aqueduct capacity is diverted to river. See schematic diagram of Tuolumne River Basin available from the California Water Science Center.

EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 18,200 ft³/s, Jan. 3, 1997, gage height, 12.33 ft; minimum daily, 12 ft³/s, Nov. 28-30, 1976.

WATER-QUALITY RECORDS

PERIOD OF RECORD -

CONTINUOUS WATER-QUALITY DATA:
WATER TEMPERATURE: Water years June 2006 to current year (water years 2006-2023, daily).

INSTRUMENTATION - Water-temperature recorder since June 1, 2006.

REMARKS - Water temperature is affected by regulation from Hetch Hetchy Dam and Early Intake.