LOCATION.-- Lat 42°26'36", long 88°14'51" (NAD of 1927), in NE1/4NW1/4 sec.25, T.46 N., R.8 E., McHenry County, Hydrologic Unit 07120006, on right bank at upstream side of bridge on Winn Road, 0.6 mi west of Spring Grove, and at mile 7.4.

DRAINAGE AREA.-- 192 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: August 1966 to current year.

STAGE: Water years 1994 to current year.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1976-91.

SEDIMENT: Dec. 1997 to May 1999.

MISCELLANEOUS: Sediment concentration and particle size, water years 1998-99.

PRECIPITATION: October 1999 to current year.

REVISED RECORDS.-- WSP 2115: 1969-70(M). WDR IL-75-1: Drainage area. WDR IL-85-2: 1966-67(M), 1971.

GAGE.-- Water stage recorder, phone telemeter, unheated tipping-bucket rain gage, and crest-stage gage. Datum of gage is 746.00 ft above NGVD of 1929.

REMARKS.-- Suspended-sediment samples were collected twice weekly with more frequent samples collected during high runoff periods. 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, 2,910 ft³/s, Sept. 26, 1986, gage height, 14.26 ft; minimum discharge, 6.6 ft³/s, Aug. 7, 1988.

SUSPENDED-SEDIMENT CONCENTRATION: Maximum daily, 244 mg/L, May 17, 1999; minimum daily, 8 mg/L, Nov. 24, 1998.

SUSPENDED-SEDIMENT LOAD: Maximum daily, 247 tons, May 17, 1999; minimum daily, 1.9 tons, Nov. 24, 1998.

PRECIPITATION: Maximum daily total, 2.82 in., June 12, 2000.

EXTREMES OUTSIDE PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Flood in April 1960 reached a stage of 13.7 ft, from information by local resident, and flood in July 1938 reached a stage of about 4 to 6 ft higher than that in April 1960.