LOCATION.-- Lat 40°52'40", long 88°38'10" (NAD of 1927), in SE1/4SW1/4 sec.22, T.28 N., R.5 E., Livingston County, Hydrologic Unit 07130002, near center of span on downstream side of bridge on Vermilion Street in Pontiac, 0.1 mi upstream from State Highway 116, 0.8 mi upstream from Turtle Creek, and at mile 60.3.

DRAINAGE AREA.-- 579 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1942 to current year.

STAGE: Water years 1994 to current year.

REVISED RECORDS.-- WDR IL-75-1: Drainage area. WDR IL-83-2: 1951, 1957, 1965(M), 1968, 1970, 1980. WDR IL-98: 1997 (P).

GAGE.-- Water-stage recorder, U.S. Army Corps of Engineers satellite telemeter, and crest-stage gage. Datum of gage is 619.45 ft above NGVD of 1929 (619.25 ft NAVD 1988). Prior to Nov. 8, 1965, nonrecording gage at same site and datum.

REMARKS.-- An average of 3 ft³/s, diverted 0.5 mi upstream from station for water supply of city of Pontiac, is not included in records.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 13,100 ft³/s, Dec. 4, 1982, gage height; 19.16 ft; no flow for many days in 1953, 1983-84, 1986-91, 2005.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Flood of May 1933 reached a stage of 17.0 ft, from flood marks, estimated discharge 11,000 ft³/s.