USGS Water-Year Summary 2024
05525000 IROQUOIS RIVER AT IROQUOIS, IL
LOCATION - Lat 40°49'23", long 87°34'54" referenced to North American Datum of 1983, in NE 1/4 SE 1/4 sec.15, T.27 N., R.11 W., Iroquois County, IL, Hydrologic Unit 07120002, on left bank at downstream side of bridge on U.S. Highway 52 in Iroquois, 500 ft. upstream from a railroad bridge, 4.5 mi. downstream from the Indiana-Illinois State line, and at mile 50.4.
DRAINAGE AREA - 686 mi².
SURFACE-WATER RECORDS
PERIOD OF RECORD -
SURFACE-WATER DISCHARGE AND STAGE
DISCHARGE: October 1944 to current.
STAGE: Water years 1994 to current.
SURFACE-WATER QUALITY
CHEMICAL: Water years 1978-91 and 2009-2012. Additional chemical data for water
years 1972-77 are published in Water-Resources Investigations 78-23
and 79-24 as site FL 04.
SEDIMENT: October 1978 to September 1980, January 1993 to December 1995.
GAGE - Water-stage recorder, satellite telemeter, and crest-stage gage. Datum of gage is 614.13 ft NAVD 1988. Prior to Aug. 5, 1945, nonrecording gage at same site and datum.
EXTREMES FOR PERIOD OF RECORD -
SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 10,400 ft³/s, June 13,
1958, gage height, 26.31 ft; minimum, 5.2 ft³/s, Sept. 13, 1964.
SUSPENDED-SEDIMENT CONCENTRATIONS: Maximum daily, 2,280 mg/L, June 2, 1980;
minimum daily, 3 mg/L, Dec. 23, 24, 27-31, 1978.
SUSPENDED-SEDIMENT LOADS: Maximum daily, 12,200 tons, June 3, 1980; minimum
daily, 0.45 ton, Dec. 28, 1978.