The letter from EPA Regional Administrator Shawn M. Garvin to Michael Krancer, secretary of the Pennsylvania Department of Environmental Protection, implies that Krancer's voluntary directive to the industry is insufficient.
"While we appreciate PA DEP's effort to reduce oil and gas wastewater discharges to Pennsylvania's waters, we believe modifications to the prior wastewater disposal practices should be legally enforceable to the greatest extent possible," Garvin said.
The EPA's letter to Pennsylvania officials was the latest effort by federal regulators to assert more influence over oil and gas drilling. The state traditionally has regulated the industry.
In March, the EPA pushed Pennsylvania to step up testing of rivers that receive treated gas-drilling wastewater, which contains salty chlorides, some metals, and radioactive materials.
Last month, the EPA dispatched a unit to respond to a well blowout in Bradford County, surprising Krancer, whose teams of inspectors were already there.
"This sense, all of a sudden, that DEP is not competent, not on the job, not doing enough, this seems to be a recent creature," Krancer said in an interview last month.
The federal actions appear to be a response to growing political pressure on Congress to regulate gas drilling and the controversial hydraulic fracturing process, which involves the high-pressure injection of fluids and sand into a well to liberate trapped oil and gas.
Fracking, as it is called, creates large amounts of wastewater, which in most states is injected deep into the earth in federally regulated wells. In Pennsylvania, whose geology is not suited for wastewater injections, the state has allowed drillers to send the fluids to treatment plants that are not equipped to adequately purify it.
Krancer last month directed Marcellus Shale drillers to halt the practice as of May 19. Most drillers said they would comply because they had developed techniques to recycle the wastewater by blending it into the fluids used in fracking new wells.
Kathryn Z. Klaber, president of the Marcellus Shale Coalition, an industry trade group, said Thursday that the industry was already "aggressively and tightly regulated" by the state, and that the EPA's latest actions were redundant.
The DEP "continues to demonstrate that states are best situated to oversee shale-gas development and related activities," she said in a statement. "EPA overstepping its regulatory authority and duplicating efforts under way at the state level, however, does not represent commonsense policy."
Myron Arnowitt, the state director of Clean Water Action, said the EPA should be even more assertive over the state.
"They are signaling to some extent that EPA is not going to come in and do something over DEP, which we think they should," he said.
Contact staff writer Andrew Maykuth at 215-854-2947 or firstname.lastname@example.org.