LOCATION.-- Lat 40°37'48", long 87°43'26" (NAD of 1927), in NW1/4NE1/4 sec.16, T.25 N., R.12 W., Iroquois County, Hydrologic Unit 07120002, on pier at downstream side of bridge on County Highway 9,200 ft downstream from Mud Creek, 1 mi west of Milford, and at mile 23.9.

DRAINAGE AREA.-- 446 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: July 1948 to current year.

STAGE: Water years 1994 to current year.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1978-91, and 1999 to 2004.

MISCELLANEOUS: Water years 2004 and 2005; Contaminants in streambed sediments, August 1999; contaminants in fish tissue, August 1999.

BIOLOGICAL

ALGAE: Water years 1999, 2002-04.

BENTHIC MACROINVERTEBRATES: Water years 1999, 2002-04.

FISH: Water years 1999, 2002-04.

HABITAT: Water years 1999-2000, 2002-04.

REVISED RECORDS.-- WDR IL-75-1: Drainage area.

GAGE.-- Water-stage recorder and phone telemeter. Datum of gage is 622.00 ft above NGVD of 1929 (621.80 ft NAVD 1988). Prior to July 23, 1970, nonrecording gage at same site and datum.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 22,900 ft³/s, Feb. 21, 1951, gage height, 20.90 ft, from rating curve extended above 8,200 ft³/s; maximum gage height, 28.16 ft, Apr. 12, 1994, discharge, 19,400 ft³/s; minimum discharge, 2.0 ft³/s, Sept. 1, 2, 7, 1972, Oct. 8, 1994.

REMARKS FOR CURRENT YEAR.--Fish community samples were collected as part of the National Water-Quality Assessment (NAWQA) program in the upper Illinois River Basin (Moulton and others, 2002). Collections were made with two passes with a barge electroshocker and supplementary seine hauls and kicks. Fishes were identified by C. A. Taylor, Illinois Natural History Survey, Champaign. Reach A begins 512 ft. downstream of Bridge 1100N, and continues downstream 820 ft.