LOCATION.-- Lat 41°53'30", long 87°38'30" (NAD of 1927), in NW1/4SW1/4 sec.12, T.40 N., R.13 E., Cook County, Hydrologic Unit 07120003, on right upstream side of Grand Avenue bridge in Chicago, 0.6 mi upstream from the confluence with the main stem of the Chicago River and at mile 36.0.

DRAINAGE AREA.-- 180 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: July 2, 2002 to current year.

SURFACE-WATER QUALITY

PHYSICAL AND CHEMICAL: Water years 2002 to current year.

WATER TEMPERATURE: September 2002 to current year.

GAGE.-- Water-stage recorder, acoustic velocity meter and water-temperature sensor. Datum of gage is 579.48 ft above NGVD of 1929 (Chicago City datum).

REMARKS.-- This station provides data for a water-quality model.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum daily discharge, 4,430 ft³/s, Aug. 22, 2002, minimum daily discharge, -20 ft³/s, Jan. 31, 2004, due to regulation.

WATER TEMPERATURE: Maximum recorded, 25.6°C, Aug. 27, 2003; minimum recorded, 0.5°C, Jan. 31, 2004.