LOCATION.-- Lat 41°59'46", long 88°17'42" (NAD of 1983), in SE1/4NW1/4 sec.35, T.41 N., R.8 E., Kane County, Hydrologic Unit 07120007, on right bank, upstream of dam in South Elgin, 0.1 mi upstream from State Street, 1.4 mi upstream from Brewster Creek, 1.4 mi downstream from Poplar Creek, and at mile 67.2.

DRAINAGE AREA.-- 1,556 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1989 to September 1998.

STAGE: July to September 1914, October 1993 to current year.

PARTIAL RECORD: Low-flow discharge measurements, July 1961 to September 1962; miscellaneous discharge measurements, water years 1978-89.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1978-91.

GAGE.-- Water-stage recorder, phone telemeter, and concrete dam. Datum of gage is 687.95 ft above NGVD of 1929 (687.70 ft NAVD 1988).

REMARKS.-- Flow regulated by Stratton Lock and Dam (previously known as McHenry dam), 30 mi upstream, and occasionally affected by wind action.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge 6,990 ft³/s, July 18, 1993, gage-height 14.45 ft.

EXTREMES OUTSIDE PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Flood of April 2, 1960, reached a stage of 8.16 ft at site 0.1 mi downstream at present datum, from floodmarks, discharge 6,550 ft³/s.