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USGS Water-Year Summary 2024
05576000 SOUTH FORK SANGAMON RIVER NEAR ROCHESTER, IL
LOCATION - Lat 39°44'32", long 89°34'02.2" referenced to North American Datum of 1983, in NE 1/4 NW 1/4 sec.20, T.15 N., R.4 W., Sangamon County, IL, Hydrologic Unit 07130007, on right bank at city of Springfield dam, 100 ft. downstream from Horse Creek, 1.7 mile southwest of Rochester, and at mile 7.4. Auxiliary gage 1.2 miles downstream.
DRAINAGE AREA - 867 mi².
REVISIONS HISTORY - WDR IL-75-1: Drainage area.
Revisions: Gage height, discharge, and associated measurements for the period Nov. 17, 2017, to Oct. 28, 2022, were revised on Nov. 22, 2022, due to the reference gage being reset in error during a gate change.
Revisions: Gage height, discharge, and associated measurements for the period Nov. 17, 2017, to Oct. 28, 2022, were revised on Nov. 22, 2022, due to the reference gage being reset in error during a gate change.
SURFACE-WATER RECORDS
PERIOD OF RECORD -
SURFACE-WATER DISCHARGE AND STAGE
DISCHARGE: July 1949 to current.
STAGE: Water years 1994 to current.
SURFACE-WATER DISCHARGE AND STAGE
DISCHARGE: July 1949 to current.
STAGE: Water years 1994 to current.
GAGE - Water-stage recorder, U.S. Army Corps of Engineers satellite telemeter, and crest-stage gage. Datum of gage is 510.90 ft above NAVD of 1988. Prior to April 6, 1966, water-stage recorder at site 2.4 mi downstream at same datum. April 29, 1975 to current, auxiliary water-stage recorder at site 1.2 mi downstream at same datum. Prior to May 19, 1950, auxiliary non-recording gage at site 6.2 mi downstream at same datum. May 19, 1950 to Apr. 29, 1975, auxiliary non-recording gage at site 1.2 mi downstream at same datum.
REMARKS - Beginning Apr. 14, 1955, occasional regulation due to diversion to Lake Springfield for Springfield's public-water supply periodically occurs just upstream from the dam between the confluence of Horse Creek and the gage. Occasional regulation occurs due to operation of the gate at the diversion dam. Pumpage from Lake Taylorville into stream generally occurs during the fall upstream from the dam.
Accuracy of records is discussed in the annual Station Analysis archived at the USGS IL Water Science Center.
EXTREMES FOR PERIOD OF RECORD -
SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 24,300 ft³/s, Dec. 30, 2015, gage height, 36.66 ft., from floodmark; no flow Nov. 4-6, 1985, Sept. 9, 1987, and many days in 1988-90, 1992, and 2000.
SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 24,300 ft³/s, Dec. 30, 2015, gage height, 36.66 ft., from floodmark; no flow Nov. 4-6, 1985, Sept. 9, 1987, and many days in 1988-90, 1992, and 2000.
