In 1996 and 1997 the Illinois Environmental Protection Agency (Illinois EPA) and the Illinois Department of Natural Resources (IDNR) cooperatively conducted an intensive survey of the Kaskaskia River basin. Stream conditions were evaluated by a collection of water quality, sediment chemistry, instream habitat, and fish community samples. Objectives of the Kaskaskia River basin survey were to: (1) Determine use support attained in the Kaskaskia River basin and sources and factors causing or contributing to use impairment for reporting under section 205(b) of the Clean Water Act; (2) Document ambient water quality conditions and specific constituents contributing to water quality degradation and assess water quality trends; (3) Evaluate biotic integrity in the basin using fish community data and assign Biological Stream Characterization (BSC) ratings to stream segments assessed; (4) Determine biotic potential for each stream segment through assessment of available aquatic habitat; and (5) Determine the status of toxic substances in the basin by examination of surface water and sediment chemistry characteristics.