LOCATION.-- Lat 40°19'49", long 90°53'46" (NAD of 1927), in SE1/4SW1/4 sec.18, T.4 N., R.4 W., McDonough County, Hydrologic Unit 07130010, on right bank at downstream side of bridge on State Highway 61, 0.2 mi downstream from a railroad bridge, 1 mi southwest of Colmar, 1.8 mi upstream from Troublesome Creek, and at mile 61.8.

DRAINAGE AREA.-- 655 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: October 1944 to current year.

STAGE: Water years 1994 to current year.

SURFACE-WATER QUALITY

CHEMICAL: Water years 1975-91 and 1998.

MISCELLANEOUS: Contaminants in streambed sediments, July 1997; contaminants in fish tissue, July 1997; streambank sediment size, October 1997; streambed sediment size, October 1997.

BIOLOGICAL

ALGAE: Water years 1996-98.

BENTHIC MACROINVERTEBRATES: Water years 1996-98.

FISH: Water year 1997-98.

HABITAT: Water years 1996-98, 2003.

GAGE.-- Water-stage recorder, U.S. Army Corps of Engineers satellite telemeter and crest-stage gage. Datum of gage is 491.53 ft above NGVD of 1929 (491.27 ft NAVD 1988). Prior to July 13, 1945, nonrecording gage at same site and datum.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 38,900 ft³/s, Mar. 5, 1985, gage height, 26.61 ft; maximum gage height, 27.03 ft, Jan. 3, 1965, ice jam; no flow part of each day Dec. 8, 9, 12, 13, 17, 21, 1955, due to temporary dam upstream; no flow Oct. 19, 1988.

REMARKS FOR CURRENT YEAR.--Algae community samples were collected as part of the National Water-Quality Assessment program (NAWQA) in the lower Illinois River Basin. A qualitative sample was collected in accordance with NAWQA protocols (Cuffney and others, 1993). The qualitative periphyton sample is a composite of all samples collected from all periphyton microhabitats present within the sampling reach. All samples were processed by the Philadelphia Academy of Natural Sciences. The reach begins 1326 ft downstream of the State Highway 61 bridge, and continues downstream 1283 ft.

Table of Contents

Introduction

Station Descriptions

Surface-Water Data

Ground-Water Data

Meteorological Data

Biological Data