LOCATION.-- Lat 40°07'27", long 89°59'06" (NAD of 1983), in NW1/4SE1/4 sec.3, T.19 N., R.8 W., Mason County, Hydrologic Unit 07130008, on right bank at downstream side of bridge on State Highway 97, 300 ft upstream from a railroad bridge, 0.8 mi downstream from Crane Creek, 1.8 mi northwest of Oakford, and at mile 25.7.

DRAINAGE AREA.-- 5,093 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1909 to March 1912, August 1914 to June 1919, March 1921 to September 1922, October 1928 to December 1933, October 1939 to current year. Monthly discharge only for some periods, published in WSP 1308.

STAGE: Water years 1994 to current year.

PARTIAL RECORD: Annual maximum, water years 1926 to 1928; 1934 to 1939.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1978-94 and 1997-98.

SEDIMENT: Water years 1981, June 1983 to September 1986, water years 1995-1997.

SPECIFIC CONDUCTANCE: Water years 1979-81.

WATER TEMPERATURE: Water years 1976-77, 1979-81.

MISCELLANEOUS: Contaminants in streambed sediments, August 1996; contaminants in fish tissue, August 1996; streambank sediment size, October 1997; streambed sediment size, October 1997; sediment concentration and particle size, water years 1993-94, 1996-98.

BIOLOGICAL

ALGAE: Water year 1981, 1996-97.

BENTHIC MACROINVERTEBRATES: Water year 1996.

FISH: Water year 1997.

HABITAT: Water year 1996, 2003.

REVISED RECORDS.-- WSP 715: 1922(M). WSP 1175: 1912(M). WDR IL-75-1: Drainage area.

GAGE.-- Water-stage recorder, U.S. Army Corps of Engineers satellite telemeter, and artificial control. Datum of gage is 452.88 ft above NGVD of 1929 (U.S. Army Corps of Engineers bench mark) (452.55 ft NAVD 1988). Prior to Oct. 1, 1939, nonrecording gage at site 2.4 mi upstream at datum 458.66 ft above NGVD of 1929 (458.33 ft NAVD 1988). Oct. 1, 1939, to May 14, 1940, nonrecording gage at present site at zero datum of NGVD of 1929 (-0.33 ft NAVD 1988).

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 123,000 ft³/s, May 20, 1943, gage height, 25.63 ft; minimum daily, 45 ft³/s, estimated, Jan. 21-31, 1918.

SUSPENDED-SEDIMENT CONCENTRATIONS: Maximum daily, 3,540 mg/L, June 9, 1984; minimum daily, 1 mg/L, Dec. 7, 8, 1996, Jan. 11, 1997.

SUSPENDED-SEDIMENT LOADS: Maximum daily, 120,000 tons, Feb. 24, 1985; minimum daily, 1.6 tons, Dec. 7, 1996.

REMARKS FOR CURRENT YEAR.--Fish community samples were collected as part of the National Water-Quality Assessment program (NAWQA), in the lower Illinois River Basin. Taxonomy is based on Robins and others(1991), except where modified for the family Moronidae (Johnson, 1984) and the order Cyprinidontiformes (Parenti, 1981). Common names were compared to the current Illinois fish species list posted by Illinois Natural History Survey. Collection methods followed Meador and others (1993). Collections were taken with a boat electroshocker and seine. Fishes were identified in the field by C. A. Taylor, Illinois Natural History Survey, Champaign. Representative specimens were preserved, identified, and vouchered at the Illinois Natural History Survey fish collection. The reach is located 591 feet upstream of the State Highway 97 bridge (gage), and continues upstream for 3264 feet.