GLMRIS Water Quality Modeling

The GLMRIS feasibility study is being undertaken to develop a long-term solution to prevent aquatic invasive species from traveling between the Great Lakes and Mississippi River watersheds. One primary goal of the study is to assess the feasibility of hydrologically separating the two watersheds, which are currently connected via the manmade Chicago Sanitary & Ship Canal and Cal-Sag Channel. These waterways were constructed in the early 20th Century, which allowed the Chicago River and other area waterways to flow to the Illinois River, instead of to Lake Michigan. Re-separating the watersheds will radically alter the existing flow patterns in the system, and is expected to cause significant water quality changes. Modeling and analysis of water quality impacts to both the CAWS and Lake Michigan are needed to ensure any selected alternative will be in compliance with Illinois water quality standards and with the Clean Water Act.