LOCATION.-- Lat 41°17'10", long 88°21'35" (NAD of 1927), in SW1/4SW1/4 sec.31, T.33 N., R.8 E., Grundy County, Hydrologic Unit 07120005, on right bank at downstream side of bridge on State Highway 113, 0.3 mi downstream from Johnny Run, 3 mi west of Coal City, and at mile 15.0.

DRAINAGE AREA.-- 455 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1939 to October 1995. October 1998 to current year.

STAGE: Water years 1994-1996;1999 to current year.

PARTIAL RECORD: Annual maximum, water years 1997-98.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1978-91.

DISSOLVED OXYGEN: Water years 2001-2003.
PH: Water years 2001-2003.

SPECIFIC CONDUCTANCE: Water years 2001-2003.

TURBIDITY: Water years 2001-2003.

WATER TEMPERATURE: Water years 2001-2003.

REVISED RECORDS.-- WSP 1035: 1943(P). WSP 1115: 1946. WDR IL-75-1: Drainage area.

GAGE.-- Water-stage recorder, U.S. Army Corps of Engineers satellite telemeter, and crest-stage gage. Datum of gage is 527.41 ft. above NGVD of 1929 (527.15 ft NAVD 1988). Prior to Apr. 30, 1940, and October 1996 to September 1998, nonrecording gage at same site and datum.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 22,400 ft³/s, Dec. 4, 1982, gage height, 19.51 ft; maximum gage height, 19.70 ft, July 15, 1958, discharge, 17,600 ft³/s, from rating extended above 12,000 ft³/s; no flow at times in many years.

EXTREMES OUTSIDE PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Flood of Aug. 8, 1924 reached a stage of about 21 ft, discharge not determined.