LOCATION.-- Lat 42°04'54", long 87°53'26" (NAD of 1983), in SE1/4SE1/4 sec.25, T.42 N., R.11 E., Cook County, Hydrologic Unit 07120004, on right bank 50 ft upstream from Dam No. 2 of Cook County Forest Preserve, 0.3 mi downstream from Lake Avenue Bridge, 1.2 mi upstream from Central Road Bridge, 2.5 mi north of Des Plaines, and at mile 69.3.

DRAINAGE AREA.-- 360 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1940 to current year.

STAGE: Water years 1994 to current year.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1978-91.

REVISED RECORDS.-- WSP 975: 1942. WDR IL-75-1: Drainage area.

GAGE.-- Water-stage recorder, phone telemeter, and masonry dam. Datum of gage is 626.31 ft above NGVD of 1929 (626.06 ft NAVD 1988). Prior to Apr. 8, 1941, nonrecording gage at same site and datum.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 4,900 ft³/s, Oct. 1, 1986, gage height, 10.88 ft; no flow many days in 1944, 1946 and Aug. 7, 8, 1962.

EXTREMES OUTSIDE PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Flood of July 4, 1938, reached a stage of 9.0 ft, from floodmark, discharge, 5,000 ft³/s.