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

ALGAE: Water year 2000.

BENTHIC MACROINVERTEBRATES: Water year 2000.

FISH: Water year 2001.

HABITAT: Water year 2000-01.

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 (607.10 ft NAVD 1988).

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. Taxonomy is based on Robins and others (1991), except where modified for the family Moronidae (Johnson, 1984) and the order Cyprinidontiformes (Parenti, 1981). 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.