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LOCATION.--Lat 43° 11'51", long 112° 22'09", in SE1/4 SW1/4 sec.33,
T.2 S., R.35 E., Bingham County, Hydrologic Unit 17040206, on left bank
immediately upstream from old Riverside Highway bridge, 0.25 mi downstream
from new U.S. Highway 26 bridge, 1.2 mi west of Blackfoot, and at mile 764.3.
DRAINAGE AREA.--9,950 mi2.
PERIOD OF RECORD.--August 1978 to current year. Records for May 1924 to
September 1932 at site downstream, published as "Snake River below Blackfoot
Bridge, near Blackfoot", are not equivalent because diversions were not included.
GAGE.--Elevation of gage is 4,490 ft above NGVD of 1929, from topographic map.
May 1924 to Sept. 1932, water-stage recorder at site downstream at different datum.
REMARKS.--Flow regulated by Jackson Lake, Palisades Reservoir, Henrys Lake,
Island Park Reservoir, and Grassy Lake, having a combined capacity of
2,570,000 acre-ft. Diversions above station for irrigation of about
750,000 acres. Considerable water leaks above the station into the
Snake River Plain aquifer.
EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 43,200 ft3/s June 17, 1997,
gage height, 13.55 ft; maximum gage height, 14.71 ft, Feb. 7, 1985, result of
backwater from ice; minimum, 2.7 ft3/s Apr. 29, 1992, gage height, 0.91 ft,
caused by irrigation diversions.
Station operated in cooperation with Water District No.1.
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