Lake Calumet is the largest body of water within the city of Chicago. Formerly a shallow, postglacial lake draining into Lake Michigan, it has been changed beyond recognition by industrial redevelopment and decay. Parts of the lake have been dredged, and other parts reshaped by landfill. Together with the rest of the city of Chicago, the remnant of the lake now drains into the Des Plaines River and the Mississippi River basin via the Cal-Sag Channel and the Chicago Sanitary and Ship Canal.