I would not be surprised any city around manufacturing (especially chemical) sooner or later ground water going to get contaminated if it not already. From 1900 to 1970s it was common for waste to be dumped on company property, some even got caught dumping straight into the rivers.

Then, there all the dumps and mining problems yet to be discovered. IMO it's only goin to get worse the further down stream you live. I noticed this 50 years ago when I was on the upper Missouri River and noticed the difference on the lower Missouri River. City, factory, farm chemical run off down stream along with what's buried in the ground has effect that IMO still hasn't reared it ugly head