In the National Water Quality Assessment (NAWQA) program, surface water activities focus on assessing physical and chemical characteristics of streamwater, including physical parameters, suspended sediment, dissolved solids, major ions and metals, nutrients, organic carbon, and dissolved pesticides, and relating these characteristics to hydrologic conditions, sources, and transport. The program also includes selected studies of other water-quality conditions, such as dissolved oxygen and pathogenic bacteria, where they are likely to be important. Selective investigations of hydrophobic organic contaminants or trace elements may be conducted if the results of Bed-Sediment and Fish Tissue studies indicate that they are significant.
Major water-quality issues in the Lower Illinois River Basin (LIRB) study area include sedimentation, toxic substances in sediment, high concentrations of nutrients and agricultural chemicals, and low dissolved oxygen concentrations. Sedimentation has resulted in the partial or complete filling of many lakes in the study area.
The Illinois River receives much of the State's human, animal, industrial, and agricultural wastes. Sediments from the Chicago metropolitan area in the Upper Illinois River Basin (UIRB) have distinct chemical characteristics; these characteristics have been identified in sediments in the LIRB. The Chicago area appears to be the source of seven U.S. Environmental Protection Agency priority pollutants in the sediments (Colman and Sanzolone, 1990).
Wastewater also carries nutrients, including phosphorus and nitrogen
are not completely removed by treatment. These nutrients can sustain the
growth of algae and lead to its overbundance, as has been the case in many
places throughout the Illinois River.
Dissolved oxygen is a basic indicator of the "health" of streamwater.
Because of urbanization of Chicago and the Peoria-Pekin area and the
construction of the Chicago Ship and Sanitary Canal (CS&S), sewage and
industrial wastes have been introduced into the Illinois River. Since the
Illinois Waterway is less able to cleanse itself due to construction such
as damming and diking, excess wastes remain in the water and produce
ammonia nitrogen, which consumes oxygen. This has resulted in low
dissolved oxygen concentrations in the LIRB.
U.S. Department of the Interior
U.S. Geological Survey
221 North Broadway, Urbana, IL 61801, USA
Last modified: 13:22 CST Thurs 11 May 2000