LOCATION.-- Lat 42°23'07", long 88°22'10" (NAD of 1927), in NE1/4NW1/4 sec.13, T.45 N., R.7 E.,McHenry County, Hydrologic Unit 07120006, on left bank at downstream side of bridge on Thompson Road, at west edge of Wonder Lake and 1.1 mi east of Greenwood at mile 19.7.

DRAINAGE AREA.-- 84.5 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: June 1994 to September 1997, October 1998 to September 2001 (discontinued).

STAGE: Water years 1994-1997;1999-2001.

PARTIAL RECORD: Annual maximum, water years 1965 to 1977.

SURFACE-WATER QUALITY

CHEMICAL: July 1994 to September 1997. Water years 1999 to 2001 (discontinued).

SEDIMENT: June 1994 to September 1997, March 1999 to July 2001 (discontinued).

MISCELLANEOUS: Water year 2000; contaminants in streambed sediments, water years 1998 and 2000; contaminants in fish tissue, water years 1998 and 1999; sediment particle size June 1994 to September 1997, March 1999 to July 2001 (discontinued); sediment concentration and particle size, water years 1996-2001.

BIOLOGICAL

ALGAE: Water years 1999-2001.

BENTHIC MACROINVERTEBRATES: Water years 1999-2001.

FISH: Water years 1999-2001.

HABITAT: Water years 1999-2001.

GAGE.-- Water-stage recorder and phone telemeter. Datum of gage is 798.00 ft above NGVD of 1929 (797.81 ft NAVD 1988). Prior to June 13, 1994, at datum 8.31 ft higher.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum gage height, 13.95 ft, present datum, June 11, 1967, discharge not determined; maximum discharge, 3,690 ft³/s, June 13, 1999, gage height, 11.63 ft; minimum discharge, 5.5 ft³/s, Sept. 12, 1995.

SUSPENDED-SEDIMENT CONCENTRATIONS: Maximum daily, 808 mg/L, Aug. 17, 1995; minimum daily, 1 mg/L, Aug. 27, 1997.

SUSPENDED-SEDIMENT LOADS: Maximum daily, 2,200 tons, June 13, 2000; minimum daily, 0.06 tons, Aug. 27, 1997.

EXTREMES OUTSIDE PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum stage of 12.26 ft, present datum, occurred between Sept. 30, 1977 and June 13, 1994, from floodmark obtained from crest-stage gage, discharge not determined.

REMARKS FOR CURRENT YEAR.--Algae community samples were collected as part of the National Water-Quality Assessment program (NAWQA) in the upper 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. Reach A is located 394 ft downstream of the Greenwood Road bridge (1.43 mi upstream of gaging station), and continues downstream for 525 ft.

Table of Contents

Introduction

Station Descriptions

Surface-Water Data

Ground-Water Data

Meteorological Data

Biological Data