LOCATION.--Lat 43° 37'56", long 115° 49'25" (NAD27), in NW1/4 NE1/4 sec.2, T.3 N., R.5 E., Boise County, Arrowrock Reservoir NE quad., Hydrologic Unit 17050112, Boise National Forest, at flow line of Arrowrock Reservoir, just downstream from unnamed tributary from the west, about 0.5 mi downstream from Cottonwood Ranger Station, and 5.5 mi northeast of Arrowrock.

DRAINAGE AREA.--20.9 mi² (revised).

PERIOD OF RECORD.--January 1939 to November 1941 (discontinued). March 1914 to September 1918, at site approximately 0.5 mi upstream, fairly equivalent except for small inflow between. Records of suspended-sediment loads for the period Jan. 23, 1939 to June 30, 1940, are published in WSP 1048.

GAGE.--Water-stage recorder and broad-crested weir. Elevation of gage is 3,090 ft above NGVD of 1929, from topographic map. Mar. 7, 1914 to Sept. 30, 1918, staff gage and concrete control 0.4 mi upstream at different datum. Jan. 23 to Feb. 8, 1939, staff gage 70 ft downstream from that site at different datum.

REMARKS.--No regulation. One small diversion above station for irrigation.

EXTREMES FOR PERIOD OF RECORD.--Maximum discharge observed, 166 ft³/s Apr. 26, 1917, gage height, 2.30 ft, site and datum then in use; minimum, 0.21 ft³/s Aug. 23, 1940, gage height, 1.96 ft6.