Such a study has not been done yet, as far as I am aware. But it is likely that when the time comes the NIMBYs will intervene and insist that such a study be done. And perhaps some wacko judge somewhere will uphold it. After all, its in the same vein as proving a negative.
That could be bad too.
Undoubtedly so. And perhaps it has an equal or higher probability than some of the scenarios already investigated (e.g., diastrophism that somehow diverts the entire flow of the Colorado River freely flowing through the drift tunnels. Overall impact? Negligible.)