LOCATION.--Lat 41°38'29.8", long 95°46'56.0" referenced to North American Datum of 1983, in NE 1/4 SE 1/4 NW 1/4 sec.19, T.79 N., R.42 W., Harrison County, IA, Hydrologic Unit 10230007, on left bank on downstream side of bridge on 8th Street in Logan, 0.5 mi downstream from Elk Grove Creek, 10.4 mi upstream from Willow Creek, and 15.7 mi upstream from mouth. (map)

DRAINAGE AREA.--871 mi².

SURFACE-WATER RECORDS

PERIOD OF RECORD.--Discharge records from May 1918 to July 1925, November 1937 to current year. May 1918 to July 1925, monthly mean discharge for some periods published in WSP 1310.

REVISED RECORDS.--WSP 956: 1938-39. WSP 1240: 1918-19, 1920 (M), 1921, 1922 (M), 1924-25, 1938 (M), 1945. WSP 1440: Drainage area.

GAGE.--Water-stage recorder. Datum of gage is 1,009.38 ft above National Geodetic Vertical Datum of 1929 (Chicago and Northwestern Railway Company benchmark). Prior to April 17, 1925, November 4, 1937, to March 16, 1952, and October 1, 1957, to October 18, 1960, non-recording gage at same site and datum; April 17 to July 1, 1925, non-recording gage at site 300 ft downstream at same datum; March 17, 1952, to September 30, 1957, non-recording gage at site 400 ft upstream at bridge on U.S. Highway 30 at same datum. Supplementary water-stage recorder operating above 4.80 ft gage height from October 22, 1946, to October 7, 1954, at site 100 ft upstream, and from October 8, 1954, to October 18, 1960, at same site, both at same datum.

WATER-QUALITY RECORDS

PERIOD OF RECORD.--Water years 2004 to current year.

PERIOD OF DAILY RECORD.--
SUSPENDED-SEDIMENT DISCHARGE: April 1939 to September 1951, records provided by U.S. Army Corps of Engineers.

Advanced Hydrologic Prediction Service

U.S. Army Corps of Engineers - Omaha District