Often hailed as one of the top public works of the 20th century, the Chicago River was reversed to protect Chicago’s drinking water supply and prevent massive outbreaks of typhoid, cholera and dysentery. The system that allowed for the reversal of the Chicago River is the Chicago Area Waterways System (CAWS).
The CAWS consists of more than 100 miles of canals and waterways, including the Chicago River, the Chicago Sanitary and Ship Canal, the Cal-Sag Channel and the Calumet Rivers. Constructed in 1900, the system moves storm water and sewage away from the city’s water supply and creates an artificial connection between the Mississippi River and Lake Michigan, allowing barges and other ships to pass between these bodies of water.
This artificial connection is what has become a source of growing concern for environmentalists, non-government organizations, industries, business leaders and public officials alike. A high-risk area for the movement of aquatic invasive species in both directions, the CAWS has already allowed zebra mussels and round goby to invade the Mississippi Basin, and more are on the way. Currently there are 10 invasive species in the Mississippi River that could use the CAWS to invade the Great Lakes and 29 species in the Great Lakes that could enter the Mississippi basin.
This is one of the greatest threats to the health of Lake Michigan and the entire Great Lakes region. They do extensive damage not only to native fish and wildlife populations, but to local economies as well. A 2012 report by Anderson Economic Group commissioned by The Nature Conservancy revealed that it costs hundreds of millions of dollars to control aquatic invasive species. Industries like sport and commercial fishing, water treatment, power generation and tourism are all affected by this threat.