Water Quality Features of the Upper Illinois Waterway

The dissolved oxygen resources of the Upper Illinois Waterway are depressed because of a combination of oxygen demand sources including carbonaceous and nitrogenous BOD, benthic biological extraction, and sediments. Because of these demands, maintenance of 6.0 mg/l DO in the stream system is difficult, and achievement of a minimum DO requirement of 5.0 mg/1 requires the nitrogenous and carbonaceous demand be substantially reduced. Water quality data obtained from field surveys are summarized together with hydraulic and hydrologic data to determine wastewater treatment needs. Collection of the waterway algal types reveals that diatoms are the dominant group comprising about 85 percent of the total densities. However, algal concentrations do not impair use of the waterway for recreation. Fecal coliform bacteria densities decrease with downstream movement at a rate of 0.77 per day in the upper pools and 0.42 per day in the lower pools. About 9 percent of the total coliform bacteria population are fecal coliforms. Only 3 of 19 stations sampled met the bacterial quality standards required by the Illinois Pollution Control Board.publishedpeer reviewedOpe