USGS Water-Year Summary 2023
11290000 Tuolumne River at Modesto, CA
LOCATION - Lat 37°37'38", long 120°59'00" referenced to North American Datum of 1927, in NW 1/4 SE 1/4 sec.33, T.3 S., R.9 E., Stanislaus County, CA, Hydrologic Unit 18040009, on left bank, 150 ft downstream from Dry Creek, 0.2 mi upstream from 9th Street Bridge.
DRAINAGE AREA - 1,884 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - 1878-84, 1891-94, 1897 (gage heights only), January 1895 to December 1896, April 1940 to current year. Monthly discharge only for some periods, published in WSP 1315-A. Water-quality data for the period October 1985 to March 1987 are available in U.S. Geological Survey Open-File Report 88-479. Water-quality data for the period April 1987 to September 1988 are available in files of the U.S. Geological Survey.
GAGE - Water-stage recorder and crest-stage gage. Datum of gage is NGVD of 1929 and 2.46 ft above NAVD of 1988. Prior to July 11, 1947, at site 2,600 ft downstream at same datum; July 11, 1947, to Nov. 16, 1953, at site 1,900 ft downstream at same datum. Nov. 17, 1953 to Apr. 28, 2004, at site 900 ft downstream, at same datum. Gage was reestablished on May 28, 2010, 1,000 ft upstream at same datum.
EXTREMES FOR PERIOD OF RECORD - (Water years 1896, and since water year 1941) Maximum discharge observed, 57,000 ft³/s, Dec. 9, 1950, elevation, 69.19 ft, maximum gage height, 71.21 ft, Jan. 4, 1997 (backwater caused by debris on railroad trestle 2,500 ft downstream of gage); minimum daily, 48 ft³/s, Sept. 9, 16, 2015.
WATER-QUALITY RECORDS
PERIOD OF RECORD -
DISCRETE WATER-QUALITY DATA:
CHEMICAL DATA: Water years 1985-88, 1993-95.
SEDIMENT: Water years 1985-88, 1993-95.
CONTINUOUS WATER-QUALITY DATA:
SPECIFIC CONDUCTANCE: Water years October 1985 to September 1988, December 1988 to March 1995, December 2000 to current year.
WATER TEMPERATURE: Water years July 1965 to April 1979, October 1985 to March 1995, December 2000 to current year.
INSTRUMENTATION - Water-quality monitor since December 2000.