Changing the Direction of the Chicago Area Waterway System - Evaluation of Physical Separation Alternatives

In 1892, the start of the Chicago Area Waterway System was put under construction to connect the Mississippi River basin with the Great Lakes basin.  These two basins were separated by a “continental divide” that did not allow for a continuous hydro connection of the two basins. With the completion of the original Chicago Sanitary and Ship Canal, a continuous connection between the two basins allowed for water to flow from the Great Lakes toward the Mississippi River, carrying raw sewage and other contaminants away from Lake Michigan where the freshwater intakes are located for the City of Chicago public water supply.

The threat of Asian carp entering the Great Lakes is one of the highest-profile issues—both ecologically and economically—in the Great Lakes region. There are five species of Asian carp, with the bighead and silver carp generating the most interest from the media, environmental and conservation groups, the fishing industry, the U.S. government and Congress, the eight Great Lakes states, Canada, and many other stakeholders. These two species of Asian carp have been migrating up the Mississippi River system since the early 1990s. In addition, the black carp was recently discovered in the lower Mississippi River and could be the most detrimental of all. The discovery of another carp species migrating northward, as well as the 39 high-risk aquatic invasive species (AIS) identified by the U.S. Army Corps of Engineers that could transfer between basins (USACE, 2011d), highlights the need for controlling the free movement of all AIS between the two basins.

This study was commissioned by the Great Lakes Commission and the Great Lakes and St. Lawrence Cities Initiative (GLC/CI) to investigate the feasibility of placing ecological barrier(s) into the Chicago Area Waterway System and identifying the impacts and benefits to stormwater and flood management, transportation and water quality.  Three alternatives were developed and presented to the GLC/CI in a January 2012 final report.