LOCATION.-- Lat 41°53'10", long 87°57'33" (NAD of 1927), in SW1/4NW1/4 sec.11, T.39 N., R.11 E., Du Page County, Hydrologic Unit 07120004, on left bank at upstream side of the Illinois Prairie Path Bikeway bridge in Elmhurst, and at mile 20.1.

DRAINAGE AREA.-- 91.5 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: June 1989 to current year.

STAGE: Water years 1994 to current year.

PARTIAL RECORD: Annual maximum, water years 1961-80.

PRECIPITATION: October 1989 to March 1996 and December 1996 to current year.

REVISED RECORDS.-- WDR IL-77-1: 1961-76(M).

GAGE.-- Water-stage recorder, phone telemeter, rain gage, and crest-stage gage. Datum of gage is 652.65 ft above NGVD of 1929. Water years 1997 and 1998, datum incorrectly published as 655.00 ft above NGVD of 1929. Prior to October 1, 1996, at site 990 ft upstream at datum 2.35 ft higher. Prior to June 1, 1989, crest-stage gage at datum 7.84 ft higher.

REMARKS.-- Occasional regulation by sewage treatment plants upstream from station. Since May 28, 1996, some flow temporarily diverted for flood control to Elmhurst Quarry Flood Control Reservoir about 1.0 miles upstream from gage. 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, 2,230 ft³/s, Aug. 27, 1972, gage height, 12.76 ft, datum 660.49 ft above NGVD of 1929, maximum gage height, 13.56 ft, Aug. 6, 1989; minimum discharge, 18 ft³/s, July 1, 1989.

PRECIPITATION: Maximum daily total, 3.67 in., September 11, 2000, but may have been greater during periods of missing record.