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USGS Water-Year Summary 2024
11526500 North Fork Trinity River at Helena, CA
LOCATION - Lat 40°46'55", long 123°07'38" referenced to North American Datum of 1927, in NW 1/4 NW 1/4 sec.21, T.34 N., R.11 W., Trinity County, CA, Hydrologic Unit 18010211, on right bank, 500 ft downstream from East Fork of North Fork Trinity River, 0.6 mi north of Helena, 1.0 mi upstream from mouth, and 6 mi northwest of Junction City.
DRAINAGE AREA - 151 mi².
REVISIONS HISTORY - WSP 1565: 1912-13.
SURFACE-WATER RECORDS
PERIOD OF RECORD - August 1911 to September 1913, January 1957 to September 1980, October 2004 to September 2005 (beginning October 2004, low-flow records only), April 2007 to November 2010 (seasonal low-flow only), April 2012 to September 2019 (seasonal low-flow only) (discontinued).
WATER TEMPERATURE: Water year 1963.
SEDIMENT DATA: Water year 1963.
GAGE - Water stage recorder. Datum of gage is 1,460 ft above NGVD of 1929, from topographic map. August 1911 to September 1913, at site 0.8 mi downstream at different datum. October 1913 to September 1980, at same site at datum 81.2 ft lower.
REMARKS - No known regulation or diversion above station. Flows computed to 1,090 ft³/s. See schematic diagram of Klamath River and Trinity River Basins available from the California Water Science Center.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 35,800 ft³/s, Dec. 22, 1964, gage height, 27.93 ft, datum then in use, from floodmarks, from rating curve extended above 9,000 ft³/s on basis of slope-area measurement of maximum flow; minimum daily, 7.5 ft³/s, Sept. 26, 1964.
