It's easy to blame the government for this horrible mistake, it's what people do, but the fact that people were working in a water department who clearly didn't know the bare bones basics of water treatment and saw no issue with how they handled things. The government is going to defer to water engineers, every time in every city in every state.
It is easy, because there are emails suggesting state officials knew about this issue back in late 2014 and yet it took, what, over a year for there to be action? And as I recall, even after people were told, they were still being charged for this poison for some time. You can't seriously act like the state owes its citizens nothing in this regard, keeping in mind the amount of time they were charging residents for poison water.
You're talking about the source of the problem here, fine, but it doesn't matter for this. Government officials made these decisions. It is completely their responsibility, even if they made the decisions in good faith that proper treatments would be used.