Credit: USACE
The Chicago Area Waterway System (CAWS) consists a series of canals and altered portions of natural rivers.
The system was built by the Metropolitan Water Reclamation District of Greater Chicago (MWRD) and completed in 1922.
The CAWS provides drainage for much of the Chicago region and is a navigation connection between the Great Lakes and the Mississippi River.
Two locks are located along the CAWS in the City of Chicago. The Chicago Lock is located at the Main Branch of the Chicago River at the entrance to Lake Michigan. The T.J. O’Brien Lock, located along the Calumet River, provides the only commercial access from CAWS to Lake Michigan.
The CAWS includes six federal navigation projects: Calumet Harbor and River; the Calumet-Saganashkee (Cal-Sag) Channel; Chicago Harbor; Chicago River; the South Branch of the Chicago River; and the Chicago Sanitary and Ship Canal. Maintenance of the projects is overseen by the U.S. Army Corps of Engineers.
A key component of the CAWS is the Chicago Sanitary and Ship Canal (CSSC), a canal system that connects the Chicago River to the Des Plaines River.
The CSSC reverses the direction of the Main Stem and the South Branch of the Chicago River, which now flows out of Lake Michigan rather than into it.
The nearby Calumet-Saganashkee Channel (CSC) provides a similar function on the Calumet River a short distance to the south, joining the Chicago canal about halfway along its route to the Des Plaines.
The two waterways provide the only navigation for marine traffic between the Great Lakes Waterway and the Mississippi River system.
The Chicago Area Waterway System poses a potential risk for the transfer of aquatic nuisance species between the two waterways.
Electric barriers are maintained in the Chicago Sanitary and Ship Canal to deter the inter-basin establishment of Invasive Asian carp and other fish.
Near Joliet, Illinois, Brandon Road Lock and Dam is a critical point to stop invasive carp from moving up the Des Plaines River towards the CAWS and eventually to the Great Lakes.
When complete, the Brandon Road Interbasin Project will include a complex series of invasive carp and aquatic nuisance species deterrents.
The Brandon Road Interbasin Project and barriers in the CAWS are part of a broad interagency invasive carp prevention effort.
Improvements in water quality have been shown to benefit fish populations in the CAWS, according to the Metropolitan Water Reclamation District of Greater Chicago.
Monitoring efforts have shown improvements in species diversity, from ten species in 1974 to 77 more recently. The overall fish population and size of individual fish have also increased as water quality has improved.