I can sort of understand some people not trusting when the EPA says the contaminants are within safe levels because I'm thinking of the Flint, MI water situation when (if I'm remembering correctly) the state environmental agency told the residents that the water was fine. Because the water looked and/or smelled and/or tasted funny or bad, some residents didn't believe the authorities and some sought independent investigations. It was an academic researcher who first researched and publicized the situation that things were not hunky dory. I know the EPA is not the same as a state environmental agency, but my point is that they are both government agencies. When people's personal sensors (nose, eyes) tell them that something isn't right, I do understand that they might want an investigation from an "independent" source.
Oh, for sure, if my water tasted or smelled funny, I'd want to get an alternative supply, even if the lab tests came back and said there was nothing at dangerous levels. Seems to me that replacement of water supplies should be the responsibility of Norfolk Southern and they should probably do it "in an abundance of caution" even if the lab tests right now don't show anything at dangerous levels. The air quality issues seem to me to be more difficult to deal with, as it's not like anyone can replace the air around the town. In any event, it seems that the toxic VOCs from the train rash have dissipated by now.
As for which government agency has the responsibility to make pronouncements about whether the water is safe or not, I'm not 100% sure, but I think that would be the State of Ohio, either the Health Department or the Ohio EPA/DNR or whatever they call themselves. The Federal environmental acts in question (Clean Water Act, Safe Drinking Water Act) are generally administered by the states under the supervision of USEPA. In fact, I'm not sure why USEPA even shows up at these incidents, except that they probably provide technical expertise that the state agencies might not have.
This is the most recent status update for the area that I could find.
The following is the latest update from Governor DeWine, the Ohio EPA, Ohio Department of Natural Resources, and Ohio Department of Agriculture regarding work underway in East Palestine.
As far as I can see, this is no Flint, MI, scenario. Some of the local environment is going to be trashed for a while, but it doesn't seem like there will be serious human casualties. It seems that if people want to get angry, they should direct that the Norfolk Southern, not the government, either Federal or state.