LOCATION.-- Lat 42°20'39", long 87°56'18" (NAD of 1927), in SE1/4SW1/4 sec.27, T.45 N., R.11 E., Lake County, Hydrologic Unit 07120004, on left bank at upstream side of bridge on State Highway 120, 2.5 mi southwest of Gurnee, and at mile 94.2.

DRAINAGE AREA.-- 232 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1945 to September 1958, October 1968 to current year.

STAGE: Water years 1994 to current year.

PARTIAL RECORD: Annual maximum, water years 1960-68.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1977-91.

PRECIPITATION: October 1999 to current year.

REVISED RECORDS.-- WDR IL-75-1: Drainage area. WDR IL-76-1: 1960(M), 1962(M). WDR IL-77-1: 1971.

GAGE.-- Water-stage recorder, phone telemeter, and rain gage. Datum of gage is 650.30 ft above NGVD of 1929 (U.S. Army Corps of Engineers bench mark). Prior to May 26, 1946, nonrecording gage. May 27, 1946, to Sept. 30, 1958, water-stage recorder. Dec. 17, 1959, to September 1968, crest-stage gage. October 1968 to September 1998, water stage recorder at site 800 ft upstream at same datum.

REMARKS.-- Effluent from sewage-treatment plants, 0.5 mi upstream. Collection, computation, and publication of precipitation data do not necessarily conform to standards used by the National Weather Service. Precipitation data could be subject to error for days with freezing and/or thawing of precipitation.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 3,890 ft³/s, May 25, 2004, gage height, 11.76 ft; maximum gage height, 11.95 ft, Sept. 27, 1986; no flow Sept. 26 to Oct. 19, 1956, and part of each day Aug. 27-30, Sept. 1, 2, 1970.

PRECIPITATION: Maximum daily total, 2.76 in., Oct. 13, 2001.