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USGS Water-Year Summary 2024
13075500 PORTNEUF RIVER AT POCATELLO, ID
LOCATION - Lat 42°52'18", long 112°28'05" referenced to North American Datum of 1983, in sec.27, T.6 S., R.34 E., Bannock County, ID, Hydrologic Unit 17040208, Pocatello South quad., on left bank 1,400 ft downstream from Carson Street Bridge at Pocatello, 1.2 mi upstream from Pocatello Creek, and at mile 16.8.
DRAINAGE AREA - 1,256 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD - May to September 1897, March 1898 to October 1899, August 1911 to current year.
GAGE - Water-stage recorder and crest-stage gage. Datum of gage is 4,421.48 feet above NAVD 1988 (USGS). May 18, 1897 to Oct. 14, 1899, non-recording gage at site 1.6 mi upstream at different datum. August 31, 1911 to May 13, 1927, and Oct. 13, 1927 to June 13, 1928, non-recording gage 0.3 mi upstream at different datum. May 14 to Oct. 12, 1927, water-stage recorder near present site at different datum. June 14, 1928 to Sept. 28, 1950, water-stage recorder near Carson Street Bridge, 0.3 mi upstream at same datum as former non-recording gages at this site. Sept. 29, 1950 to May 20, 1968, water-stage recorder at Fremont Street site, 1.0 mi upstream at datum 18.57 ft higher.
REMARKS - Flow regulated by Portneuf Reservoir, an earthen dam completed in 1912 and raised 7 ft in 1950; capacity, 23,695 acre-ft (capacity prior to 1950, 16,410 acre-ft); and Chesterfield Reservoir, capacity, 685 acre-ft. Diversions above station for irrigation of about 55,000 acres, of which about 13,000 acres are irrigated by withdrawals from groundwater (1966 determination).
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 2,990 ft³/s Feb. 14, 1962, gage height, 11.35 ft, site and datum then in use; maximum gage height, 14.56 ft, January 21, 1987, backwater from ice; minimum daily discharge, 0.23 ft³/s July 19, 1979.
