Chicago Sanitary and Ship Canal

The Chicago Sanitary and Ship Canal, historically known as the Chicago Drainage Canal, is a 28-mile-long canal system that connects the Chicago River to the Des Plaines River. It 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 related Calumet-Saganashkee Channel does the same for the Calumet River a short distance to the south, joining the Chicago canal about halfway along its route to the Des Plaines. The two provide the only navigation for ships between the Great Lakes Waterway and the Mississippi River system.

The canal was primarily built as a sewage treatment scheme. Prior to its opening in 1900, sewage from the city of Chicago was dumped into the Chicago River and flowed into Lake Michigan. The city's drinking water supply was located offshore, and there were fears that the sewage could reach the intake and cause serious disease outbreaks. Since the sewer systems were already flowing into the river, the decision was made to dam the river and reverse its flow, thereby sending all the sewage inland where it could be treated before emptying it into the Des Plaines.

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