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Technical Report

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Water Quality, Illinois River, Designated Uses, Trends


The Illinois River and its tributaries have many uses that have been designated by the Arkansas Department of Environmental Quality including fisheries, aquatic life, primary contact waters, secondary contact waters, drinking water supply, and agricultural and industrial water supply, and water quality affects whether these uses can be supported. Since water quality can be quite complex, many types of measurements can be used as water quality indicators; some common water quality measurements include pH, dissolved oxygen concentration, and conductivity. More complicated measurements include determining nutrients, sediment and bacteria in the water, as well as assessing the aquatic life—aquatic insects, fish, algae and plants that are present within a stream. Most of these parameters are related to the type and use of land surrounding the stream and thus can be impacted by human activities. This publication details stream use classification and use support, impaired reaches in the Arkansas portion of the Illinois River, general water quality conditions across the Upper Illinois River Watershed, and trends in water quality in the Illinois River over the past decade. This publication serves as companion material to MSC Publication 355, Final Report to the Illinois River Watershed Partnership: Recommended Watershed Based Strategy for the Upper Illinois River Watershed, Northwest Arkansas

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