LOCATION.-- Lat 42°25'33", long 88°09'53" (NAD of 1927), in SW1/4NE1/4 sec.34, T.46 N., R.9 E., Lake County, Hydrologic Unit 07120006, on right bank at downstream side of bridge on Grass Lake Road in Lotus Woods, 10.8 mi upstream from Stratton Lock and Dam, and at river mile 108.5.

DRAINAGE AREA.-- 919 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: December 1997 to May 1999 (discontinued).

STAGE: January 1998 to June 1999.

PARTIAL RECORD: Discharge measurements, December 1974 to July 1975.

SURFACE-WATER QUALITY

SEDIMENT: December 1997 to May 1999 (discontinued).

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

GAGE.-- Water-stage recorder, phone telemeter, and acoustical-velocity meter. Datum of gage is 733.00 ft above NGVD of 1929 (levels by Illinois Department of Transportation).

REMARKS.-- Stage regulated by Stratton Lock and Dam, 5.5 mi downstream from station (previously known as McHenry Dam). Suspended-sediment samples were collected twice weekly with more frequent samples collected during high runoff periods.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum gage height 5.58 ft, April 28, 1999, discharge not determined.

SUSPENDED-SEDIMENT CONCENTRATION: Maximum daily, 246 mg/L, Nov. 1, 1998; minimum daily, 3 mg/L, Jan. 20-24, 1998.

SUSPENDED-SEDIMENT LOAD: Maximum daily, 1,090 tons, April 27, 1999; minimum daily, 5.2 tons, Jan. 21, 1998.