Not only did Michigan Governor Rick Snyder's top advisers know all about the poisoning of Flint, they also expressed concerns for members of their own families.
Emails obtained by the Detroit News show Snyder's most senior advisers discussing the gravity of the situation over a year ago in October of 2014.
Valerie Brader, then Snyder’s environmental policy adviser, requested that the governor’s office ask Flint’s emergency manager to return to Detroit’s system on Oct. 14, 2014, three weeks before Snyder’s re-election.
Mike Gadola, then the governor’s chief legal counsel, agreed Flint should be switched back to Detroit water nearly a year before state officials relented to public pressure and independent research showing elevated levels of lead in the water and bloodstreams of Flint residents. [...]
Gadola said his mother remains a resident of Flint, adding a personal alarm to his message that was received by Snyder’s Chief of Staff Dennis Muchmore, Deputy Chief of Staff Beth Clement and then-Communications Director Jarrod Agen and Brader.
I don't know if you could call any of this a "smoking gun" but I do think it might as close as we're going to get unless Snyder's current and former staff turn against him and start spilling their guts.
As damning as the evidence against Snyder may become, I still doubt he will face any serious consequences for his lack of action, but that doesn't mean I don't hope he will.
The people of Flint drank and bathed with poisoned water for over a year because the Snyder administration didn't care enough to stop it. I don't see another way of looking at it. Snyder's office didn't consider it a priority or they didn't consider it to be a problem. Either way, they didn't care.