Of course it was. They had been trying to gain Superfund status for this location for quite a number of years. This helped it right along.
You are correct.
A bit of history listed by posting date:
Letter to Editor PREDICTED COLORADO EPA SPILL So EPA Could Secure Superfund Status
EPA accused at hearing of doctoring video from Gold King Mine spill
House panel chairman: Gold King mine was breached on purpose ( EPA )
EPAs Gold King Mine Blowout Was No Accident
EPA Withheld Key Info On Post-Spill Funding To Gold King Mine Culprit
Hope I got all of the links right.