USGS Water-Year Summary 2022
05533000 FLAG CREEK NEAR WILLOW SPRINGS, IL
LOCATION - Lat 41°44'20", long 87°53'48" referenced to North American Datum of 1983, in NE 1/4 NE 1/4 SE 1/4 sec.31, T.38 N., R.12 E., Cook County, IL, Hydrologic Unit 07120004, on left bank at upstream side of bridge on German Church Road, 1.1 mi northwest of Willow Springs, and at mile 2.2.
DRAINAGE AREA - 16.5 mi².
- WDR IL-75-1: Drainage area.
PERIOD OF RECORD -
SURFACE-WATER DISCHARGE AND STAGE
DISCHARGE: July 1951 to current year.
STAGE: Water years 1994 to current year.
MISCELLANEOUS: Water year 2000; contaminants in streambed sediments, water year 2000.
ALGAE: Water year 2000.
BENTHIC MACROINVERTEBRATES: Water year 2000.
FISH: Water year 2001.
HABITAT: Water year 2000-01.
GAGE - Water-stage recorder, phone telemeter, and crest-stage gage. Datum of
gage is 606.36 ft above NGVD of 1929 (606.08 ft NAVD 1988). Prior to June 17, 1963, water-stage recorder at same site at datum 3.73 ft higher. However, datum incorrectly published as 609.64 ft above NGVD of 1929 from 1951 to 1963. June 17, 1963, to June 26, 1964, nonrecording gage at site 0.5 mi upstream at datum 4.82 ft higher.
EXTREMES FOR PERIOD OF RECORD -
SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 2,880 ft³/s, May 17, 2020, gage height, 10.95ft; minimum daily, 0.1 ft³/s, Dec. 9, 1957.