So I don't know the specifics here and I don't doubt there is substantial environmental impact.

Do want to point out though that whenever my area has construction on water pipes we often have a flush water notice where we need to basically run our taps to flush out dirt and debris that got in during construction. Several pipes in my neighborhood were replaced in the past couple of years and we had to do it every few months. I could see that being the cause here too, if the neighborhoods are anywhere near said water pipe construction.

I do doubt the EPA will do jack about any of it. They might go out and do some survey and shake down the organization funding the work for a bribe, but there's no way they're gonna stop it if they pay up in those closed door conversations.