LOCATION.-- Lat 40°50'08", long 88°17'56" (NAD of 1927), in SE1/4SE1/4 sec.4, T.27 N., R.8 E., Livingston County, Hydrologic Unit 07130002, at bridge on County Highway 3, 1.2 mi northwest of Charlotte, and 5.5 mi north of Chatsworth.

DRAINAGE AREA.-- 186 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1942 to September 1962.

PARTIAL RECORD: Annual maximum, water years 1963 to current.

BIOLOGICAL: Benthic macroinvertebrates, water year 1997.

GAGE.-- Crest-stage gage. Datum of gage is 638.00 ft. above NGVD of 1929 (Corps of Engineers benchmark). Prior to Jan. 14, 1943, nonrecording gage at same site at datum 2.00 ft. higher. Jan 14, 1943 to Sept. 30, 1954, water-stage recorder at same site at datum 2 ft. higher.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 4,900 ft³/s March 11, 1990, gage height, 16.88 ft; maximum gage height, 17.09 ft, Oct. 3, 1986, discharge, 4,900 ft³/s; no flow for many days in several years.

REMARKS FOR CURRENT YEAR.--Benthic macroinvertebrate community samples were collected as part of the National Water-Quality Assessment program (NAWQA) in the lower Illinois River Basin. One quantitative (Richest-Targeted Habitat) sample was collected in accordance with the NAWQA protocols (Cuffney and others, 1993). The quantitative sample was a composite of macroinvertebrates from about 10 submerged tree branches. Branches were cut underwater, gathered in a 425µm mesh net, and invertebrates were washed or picked from the branches. The average length and average diameter of each branch were measured and used to calculate an approximate surface area. All samples were processed by the USGS National Water-Quality Laboratory. Phylum, Class, Order, Suborder, Family, Subfamily, and Tribe are listed and arranged according to the USGS National Water-Quality Laboratory taxonomic hierarchy. The reach begins 57 meters downstream from the bridge at County Road 3300 E, northwest of Charlotte. The surface area sampled at reach A was 0.12 m².