LOCATION.-- Lat 41°25'43", long 88°10'53", in NE1/4SW1/4 sec.15,T.34 N., R.9 E., in hydrologic unit 07120004 at center of pool between foot Treats Island and Smiths Bridge, just above the mouth of Jackson Creek, 2 1/2 miles southwest of Millsdale, Ill, and at mile 5.5..

DRAINAGE AREA.-- 1,170 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: April 1903 to December 1904.

STAGE: January 1903 to December 1904.

GAGE.-- Vertical staff gage read daily. Datum of gage is set with its zero at the same elevation as the zero of the Chicago datum, (-72.00 ft at top of gage and -84.00 ft at bottom of gage), thus giving directly the elevation of the river surface below this datum. All gage heights are negative, being below Chicago datum.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum gage height, -74.37 ft, Mar. 25, 1904; minimum gage height, -84.50 ft, Nov. 15, 1903.