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Impaired Water Quality

Illinois rivers are impaired for a variety of reasons, including sedimentation, phosphorus, nitrogen, atrazine, and fecal coliform. Once beavers were trapped out of existence in Illinois, our river systems devolved from being complex, multichannel, slower moving, and soggy to being simple, single channel, and fast moving, without wetlands and the riparian vegetation that would filter out pollutants and sediment.

Our industrialized society has placed huge demands on our rivers in the form of recreational activities, stormwater and wastewater discharge, agricultural runoff, concentrated animal feeding operations, and other point source and nonpoint source discharges. Simply put, our rivers can't keep up with the demands being placed on them.
Lime Green Algae Floating in a Forest Pond
The agricultural states whose rivers feed into the Mississippi River know this is an enormous problem. The Illinois Department of Agriculture releases a Nutrient Loss Reduction Strategy biennial report to discuss efforts to reduce the amount of nitrogen and phosphorus that is entering our rivers. Strategies discussed in the 2019 report include growing cover crops, reducing the amount of nitrogen and phosphorus, and “constructed” wetlands--but the number of acres under “constructed” wetlands is relatively very low. 

Process-based restoration, including expanding beaver habitat, would allow us to restore rivers at a fraction of the cost of conventional river restoration, creating complex river-wetland corridors that would prevent much of the sediment and pollutants from entering the river and filtering out what does enter upstream.

In our region, Iowa is currently studying the effect of beaver dams on water quality.

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