Chicago has an extensive network of sewage and rainwater tunnels whose construction started in 1970s. Reportedly the deep tunnel system of sewers cost the taxpayers around $3 billion.

Yet, whenever there is a heavy rain, Chicago's tunnel system is overwhelmed and the bacteria-laden sewage and the rainwater is flushed into the local waterways and the Lake Michigan. We are talking about a city of 7 million residents when also the suburbs taken into account.

I would say; expect some serious tunneling project within a decade in Chicago.

For the time being, you can enjoy the excellent reporting of Chicago Tribune.

https://www.chicagotribune.com/news/environment/ct-heavy-rains-sewage-chicago-20200515-4rxpjn7hargw3avja6igpvwgxu-story.html