LOCATION.--Lat 42° 39'10", long 113° 01'00" (NAD27), in NW1/4 NE1/4 SW1/4 sec.12, T.9 S., R.29 E., Power County, Register Rock quad., Hydrologic Unit 17040209, on right bank 700 ft east of Register Rock historical site, 150 ft downstream from Interstate Highway 86, 0.3 mi upstream from Snake River, and 12 mi southwest of American Falls.

DRAINAGE AREA.--324 mi², revised.

PERIOD OF RECORD.--October 1978 to September 1980, April 1985 to September 1990 (discontinued).

GAGE.--Water-stage recorder. Elevation of gage is 4,220 ft above NGVD of 1929, from topographic map.

REMARKS.--Many small diversions above station for irrigation.

EXTREMES FOR PERIOD OF RECORD.--Maximum discharge, 3,990 ft³/s Jan. 13, 1980, gage height, 8.80 ft, site and datum then in use, on basis of slope-area measurement; no flow for many days July and August 1989.

EXTREMES OUTSIDE PERIOD OF RECORD.--Maximum discharge, 7,950 ft³/s Dec. 23, 1964, on basis of contracted opening survey.