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Assessment of processes affecting low-flow water quality of Cedar Creek, west-central Illinois

Water-Resources Investigations Report 88-4141

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Abstract

Water quality and the processes that affect dissolved oxygen, nutrient (nitrogen and phosphorus species), and algal concentrations were evaluated for a 23.8-mile reach of Cedar Creek near Galesburg, west-central Illinois, during periods of warm-weather, low-flow conditions. Water quality samples were collected and stream conditions were measured over a diel (24 hour) period on three occasions during July and August 1985. Analysis of data from the diel-sampling periods indicates that concentrations of iron, copper, manganese, phenols, and total dissolved-solids exceeded Illinois ' general-use water quality standards in some locations. Dissolved-oxygen concentrations were less than the State minimum standard throughout much of the study reach. These data were used to calibrate and verify a one-dimensional, steady-state, water quality model. The computer model was used to assess the relative effects on low-flow water quality of processes such as algal photosynthesis and respiration, ammonia oxidation, biochemical oxygen demand, sediment oxygen demand, and stream reaeration. Results from model simulations and sensitivity analysis indicate that sediment oxygen demand is the principal cause of low dissolved-oxygen concentrations in the creek. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Assessment of processes affecting low-flow water quality of Cedar Creek, west-central Illinois
Series title:
Water-Resources Investigations Report
Series number:
88-4141
Edition:
-
Year Published:
1989
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
ix, 70 p. :ill., maps ;28 cm.