LOCATION.-- Lat 39°22'42", long 89°56'50" (NAD of 1927), in SE1/4SE1/4 sec.23, T.11 N., R.8 W., Macoupin County, Hydrologic Unit 07130012, on right bank at downstream side of county highway bridge, 3.0 mi downstream from confluence of East and West Forks, 4.0 mi southeast of Palmyra, and at mile 21.7.

DRAINAGE AREA.-- 61.1 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1959 to October 1980.

REVISED RECORDS.-- WDR IL-74: 1960(P). WDR IL-75: DRAINAGE AREA.

GAGE.-- Water-stage recorder. Datum of gage is 544.30 ft above NGVD of 1929.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 11,900 ft³/s Apr. 23, 1966, gage height, 11.91 ft, from rating curve extended above 3,700 ft³/s; no flow for many days in most years.

EXTREMES OUTSIDE PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Flood in May 1943 reached a discharge of 15,000 ft³/s, on the basis of contracted-opening measurement of peak flow.