LOCATION.-- Lat 40°28'34", long 89°53'18" (NAD of 1927), in SE1/4NW1/4, sec. 25, T. 6N, R5E., Fulton County, Hydrologic Unit 07130003, on right bank at abandoned lock 0.6 mi downstream from the mouth of Copperas Creek, 17.4 mi upstream from mouth of Spoon River and 136.8 mi upstream from the mouth of the Illinois River. This auxiliary gage is 8.6 mi downstream from the base gage Illinois River at Kingston Mines (05568500), and is located at mile 136.8.

DRAINAGE AREA.-- 15,390 mi². Area does not include diversion from Lake Michigan through the Chicago Sanitary and Ship Canal, which has occurred since Jan. 17, 1900.

PERIOD OF RECORD.--

STAGE: October 1993 to current year. December 1941 to September 1993 available from Illinois Water Science Center files.

GAGE.-- Water-stage recorder with phone telemeter and U.S. Army Corps of Engineers satellite telemeter 0.6 mi downstream from mouth of Copperas Creek. Datum of gage is 428.00 ft above NGVD of 1929. Prior to Oct. 30, 1967 and Nov. 9, 1999 to Oct. 29, 2002, gage located at the mouth of Copperas Creek 0.6 mi upstream of lock at same datum. Prior to Dec. 1941, nonrecording U.S. Army Corps of Engineers gage at Copperas Creek lock with datum 2.67 ft lower.

EXTREMES FOR PERIOD OF RECORD.--

STAGE: Maximum gage height, 24.70 ft, May 25, 1943; minimum recorded, 1.59 ft, Sept. 3, 2000.