This is a big problem for cities as they grow - heavy rains cause sewage outflow events. Chicago has spent 3 billion dollars on a massive underground tunnel sy

This is a big problem for cities as they grow - heavy rains cause sewage outflow events. Chicago has spent 3 billion dollars on a massive underground tunnel system to try and mitigate this to help clean up the Chicago river. https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan https://en.wikipedia.org/wiki/Tunnel_and_Reservoir_Plan Some more reading about the river cleanup project: https://interactive.wttw.com/chicago-river-tour/can-we-swim-river-yet https://interactive.wttw.com/chicago-river-tour/can-we-swim-... Anyways - yes - lots of cities near watersheds have this problem. I would say most - fecal coliform counts have been high enough to justify warnings a variety of places I've fished or vacationed. Sometimes not that big of cities.