USGS Water-Year Summary 2020
12335100 BLACKFOOT RIVER ABOVE NEVADA CREEK, NEAR HELMVILLE, MT
LOCATION - Lat 46°55'07.66", long 113°00'53.95" referenced to North American Datum of 1983, in SW 1/4 SW 1/4 SE 1/4 sec.32, T.14 N., R.11 W., Powell County, MT, Hydrologic Unit 17010203, on right bank 40 ft downstream from county road bridge, 1.9 mi south of Browns Lake, 4.2 mi upstream from Nevada Creek, 4.4 mi northwest of Helmville, and at river mile 72.0.
DRAINAGE AREA - 498 mi².
- Discharge for Feb. 28, 2017, was revised on May 1, 2020, based on routine audit findings on May 1, 2020.
PERIOD OF RECORD - October 1999 to October 2017. July 2018 to current year. Water year 2007 seasonal records only. Records equivalent to those published as "12335000 Blackfoot River near Helmville," September 1940 to October 1953 at site 13.5 mi upstream.
GAGE - Water-stage recorder. Elevation of gage is 4,250 ft, revised, referenced to the North American Vertical Datum of 1988.
EXTREMES OUTSIDE PERIOD OF RECORD - Flood of June 5, 1953 reached a discharge of 6,040 ft³/s at 12335000 Blackfoot River near Helmville.
PERIOD OF RECORD - September 1995 to September 2013.
PERIOD OF DAILY RECORD - WATER TEMPERATURE: October 2001 to September 2003, October 2004 to September 2005, and October 2007 to September 2008.
INSTRUMENTATION - Water temperature probe was installed Sept. 22, 1999.
EXTREMES FOR PERIOD OF RECORD - WATER TEMPERATURE: Maximum, 19.5°C, Aug. 18, 2008; minimum 0.0°C, many days during winter months.
EXTREMES OUTSIDE PERIOD OF RECORD - WATER TEMPERATURE: Maximum 22.5°C, July 22 and 25, 2006. Daily temperature records were maintained, but not published from October 1999 through September 2006.
EXTREMES FOR CURRENT YEAR - WATER TEMPERATURE: Maximum, 19.5°C, Aug. 2-3, 21-22; minimum 0.0°C, many days November to March.