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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.
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.
Illinois — a major feeder to the Gulf of Mexico dead zone — falls behind federal goal to reduce phosphorus and nitrogen flowing into its waterways, Morgan Greene, The Chicago Tribune, December 20, 2021
Illinois 303(d) List of Impaired Rivers
Beavers and the Dams They Build Can Improve Water Quality
Dam! Impacts of Beaver Dams on Surface and Groundwater Quality
Excess Nutrients, Illinois EPA
- How's My Waterway?
- Beavers could be Colorado's secret weapon to cleaning rivers and abandoned mines
- Healthy Floodplains Reduce Nutrient Pollution
- Nutrient Retention in Ecologically Functional Floodplains: A Review
- The effect of beaver ponds on water quality in rural coastal plain streams
- Beaver Pond Biogeochemical Effects in the Maryland Coastal Plain
- Reduction of High Nitrate Concentrations in a Central New York State Stream Impounded by Beaver
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