LOCATION.--Lat 43°12'52", long 96°17'39" referenced to North American Datum of 1927, in NW 1/4 NW 1/4 NW 1/4 sec.21, T.97 N., R.46 W., Sioux County, IA, Hydrologic Unit 10170204, on left bank 15 ft upstream from bridge on County Highway K30, 0.3 mi north of Rock Valley, and 19.4 mi upstream from mouth. (map)

DRAINAGE AREA.--1,592 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD.--Discharge records from June 1948 to current year.

REVISED RECORDS.--WSP 1439: Drainage area.

GAGE.--Water-stage recorder. Datum of gage is 1,222.54 ft above National Geodetic Vertical Datum of 1929. Prior to August 13, 1952, non-recording gage at site 3.2 mi downstream at datum 10.73 ft lower, with supplementary water-stage recorder operating above 6.23 ft gage height from June 4, 1949, to August 12, 1952; August 13, 1952, to May 4, 1976, water-stage recorder at site 3.2 mi downstream at datum 10.73 ft lower.

Advanced Hydrologic Prediction Service

U.S. Army Corps of Engineers - Omaha District