Pennsylvania has had quite a few violations of the regulations by Marcellus shale drillers. And it should be kept in mind that these are only the reported violations. How many went unreported, we will never know.
Eventually, there will be a lot of watchers, so the Marcellus shale gas drillers should really embrace the regulation, including by EPA, as a means of working together with concerned citizens. So long as the industry claims regulatory enhancements are unnecessary, they will be suspect.