Chicago Watershed
Watersheds: Chicago
Chicago Watershed
The Chicago Watershed extends into a small portion of Lake County. The watershed drains about 57,000 acres in Indiana. However, most of the Chicago Watershed lies in Illinois.
At one time the Chicago River drained into Lake Michigan, but the river's flow was reversed in the late 19th century and it now flows toward the Des Plaines River, then into the Illinois River, and after that into the Mississippi River and ultimately the Gulf of Mexico.
The United States Geological Survey has assigned the Chicago Watershed an 8-Digit Hydrologic Unit Code of 07120003.