ON TO 2050 Layer: Watershed Integrity

The watershed integrity local strategy map shows percent impervious surface by catchment, which is one of many indicators that can be used to assess the quality of aquatic resources. Many the region’s water resources are still not meeting all goals of the Clean Water Act, designated uses, Water Quality Standards, or measures of biological quality. In addition to CSOs, nonpoint source pollution, including urban stormwater and agricultural runoff, is the major source of water quality impairment today. Helping to reduce the flow of nonpoint source pollution into our waterways is an area where CMAP can provide guidance and influence. At the watershed scale, impervious cover can lead to water pollution, erosion, and degraded stream health. Research has shown that subwatersheds with less than 10 percent impervious cover tend to maintain the health of streams.1 Further increases of impervious cover can lead to impacted streams that could be restored with intervention. In locations with low imperviousness, the strategies would focus on land preservation, compact and conservation design development, and green infrastructure. However, once impervious surfaces cover the majority of the watershed, recovering pre-development stream conditions can be difficult or impossible. At that point, the policy recommendation emphasizes green infrastructure retrofits and waterway restoration that improves habitat.

Data and Resources

Additional Info

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Author Chicago Metropolitan Agency for Planning
Maintainer Chicago Metropolitan Agency for Planning
Version 2017
Last Updated October 26, 2020, 18:22
Created September 18, 2018, 22:14