The cynical collusion between corporations and government to gut the regulations that keep our water safe and clean is tackled in compelling, infuriating fashion in Cullen Hoback’s investigative documentary. The filmmaker begins by following the effects of a dangerous leak in the unfortunately named West Virginia coal-mining community of Chemical Valley, an area to which Hoback himself has some personal connections. But he gradually expands his exposé, showing not just the back-room dealings and stonewalling that allow these kinds of calamities to continue, but also the slow, dispiriting way that power corrupts even those public servants and doctors who may have begun their careers with the noblest of intentions.

There’s a lot to cover here, and Hoback isn’t always able to keep all his various threads in focus: The issues raised in this film are, as you may expect, extremely intricate. And the director does have a tendency to put himself in front of the camera a bit too much. But overall, this is a worthy, informative documentary about a subject critical to our health.