The Eagle Creek Watershed, south of Harrisburg in southern Illinois has historically been impacted from extensive coal mining operations. Knowledge of the stream quality problems caused by mining activities prompted designation of this stream as a priority water body in the 1982-1983 Illinois Water Quality Report (IEPA 1984). In late summer 1986, a stream quality investigation was initiated to determine the current status of Eagle Creek. Aquatic macroinvertebrate and water quality samples were collected from eight locations in the Eagle Creek watershed; fish populations, stream habitat and sediment chemistry were assessed at selected basin sites (Appendix Table A). Objectives of this assessment were to: Document ambient water quality conditions and any problems resulting from coal mining activities in the basin; Evaluate biotic integrity in the basin using aquatic macroinvertebrate and fish communities; Determine aquatic life use support attainment and factors causing or contributing to use impairment; Assign a Biological Stream Characterization (BSC) rating to stream segments assessed; and Determine sediment chemistry characteristics and document constituents present at abnormal levels.