LOCATION.-- Lat 41°38'48", long 87°45'59" (NAD of 1927), in SW1/4SE1/4 sec.32, T.37 N., R.13 E., Cook County, Hydrologic Unit 07120003, on left bank at downstream side of bridge on 135th Street, 1.5 mi west of State Highway 50, 3 mi southeast of Palos Park, and at mile 1.8.

DRAINAGE AREA.-- 11.2 mi².

PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE

DISCHARGE: July 1951 to current year. Prior to October 1952, records published with those for streams in the St. Lawrence River basin (WSP 1237).

STAGE: Water years 1994 to current year.

SURFACE-WATER QUALITY

MISCELLANEOUS: Water year 2000; contaminants in streambed sediments, water year 2000.

BIOLOGICAL

BENTHIC MACROINVERTEBRATES: Water year 2000.

FISH: Water year 2001.

HABITAT: Water year 2000.

REVISED RECORDS.-- WDR IL-75-1: Drainage area. WDR IL-81-2: 1955(M), 1957(M), 1970(M), 1978(M).

GAGE.-- Water-stage recorder and phone telemeter. Datum of gage is 607.40 ft above NGVD of 1929.

EXTREMES FOR PERIOD OF RECORD.--

SURFACE-WATER DISCHARGE AND STAGE: Maximum discharge, 2,010 ft³/s, July 18, 1996, from rating curve extended above 800 ft³/s on basis of indirect measurement of flow through culvert, gage height, 10.25 ft; maximum gage height, 10.30 ft, discharge, 1,930 ft³/s, Oct. 10, 1954; no flow at times in most years.

REMARKS FOR CURRENT YEAR.--Fish community samples were collected as part of the National Water-Quality Assessment program (NAWQA) in the upper Illinois River Basin. Collections were made with a single pass of the entire reach with a barge or a backpack electroshocker with supplementary seine hauls and kicks. Fishes were identified by C. A. Taylor, Illinois Natural History Survey, Champaign. Reach A begins 666 feet downstream of 135th Street and continues downstream for 623 feet.