The Chicago River

The Chicago river is probably the tamest in the world. It has been engineered to reverse its flow, and since the year 1900 it flows out of Lake Michigan. As you can see from these photos, this segment of the river has been straightened out. Unfortunately, it can’t take much rain. It floods if it rains for more than one and a half inch in a couple of hours.

The reversed flow eventually connects Lake Michigan with the Mississippi river system. This bit of geo-engineering was,quite appropriately, celebrated by the American Society of Civil Engineers as the biggest civil engineering project of the last millennium. The reversal of flow was originally meant to check pollution of the drinking water from Lake Michigan. Next it served water-borne commerce. Now, it also provides a pathway for invasive species to spread from the lakes into the rest of the USA.


The bridges that you see in the photo can all be raised. I tried to keep a watch for this, but never saw it happening. Since water traffic has decreased tremendously in recent decades, barriers are now being built to prevent invasion by invasive mussels and carps from spreading into the Mississippi river waters.