In the mid-80’s the Fox Valley Paper Mill came to the attention of a super-team. They found it was a cover for a sinister secret organization that had been using it as a base of operations. They raided the base. Between the arrest of most of upper management and the collateral damage (from the super battle and the frantic destruction of evidence) to the buildings, the mill was shut down.
The community met this with mixed reactions. On the one hand, nobody wants villains in their back yard. On the other hand, the mill was the area’s largest employer, and the raid put a lot of local families on the unemployment rolls.
The mill buildings remain unrepaired and abandoned.
As the mill had been the worst offender for illegal dumping, most people suspect that it was the cause of the Fox Valley mutant cluster. There was, in fact, a small dropoff of eruptions a few years after the base was shut down, but the numbers picked back up again when the children of the first generation to be exposed began to hit adolescence.