LOCATION.-- Lat 40°57'15", long 89°18'30" (NAD of 1927), in SW1/4 sec.23, T.29 N., R.2 W., Marshall County, Hydrologic Unit 07130001, on left bank at downstream side of highway bridge, 200 ft downstream from Atchison, Topeka and Santa Fe Railway bridge, 2.0 mi downstream from unnamed tributary, and 2.5 mi northwest of Washburn.

DRAINAGE AREA.-- 123 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1944 to October 1971.

BIOLOGICAL: Benthic macroinvertebrates, Water year 1997.

REVISED RECORDS.-- WSP 1308: 1945(M).

GAGE.-- Water-stage recorder. Datum of gage is 557.70 ft above NGVD of 1929. Prior to July 2, 1945, nonrecording gage at same site and datum.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 5,750 ft³/s, May 28, 1954, gage height, 11.85 ft; no flow for several days in most 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 downstream from the bridge at County Road 1700 E, north of Washburn. The surface area sampled at reach A was 0.29 m².