The U.S. Environmental Protection Agency may be growing footsore in its struggle to regulate hydraulic fracturing (fracking) or may simply have decided not to try to fight every battle. On June 20, the agency said it would abandon its attempt to prove a connection between fracking and drinking water contamination in the state of Wyoming. Instead, it plans to leave further investigation of the "Pavillion" case to state authorities, who for the most part have been critical of its efforts.

In December 2011, the EPA said it had found that fluids used in shale gas drilling had released "unsafe levels" of benzene into an aquifer in the town of Pavillion and would submit its findings to peer review. Over the past year and a half, however, it has extended public comment periods on a draft report three times, each time delaying the review plans. The state government, which apparently does not plan a peer review, has said it will release its findings at the end of September 2014.

"We believe that EPA's focus going forward should be on using our resources to support Wyoming's efforts, which will build on EPA's monitoring results," acting administrator Bob Perciasepe said, explaining the decision. According to news agencies, the state's studies will be funded in part by a $1.5 million grant from Encana, which owns the Pavillion field. The company is the U.S. subsidiary of Canadian energy company Encana.

While environmentalists contend the EPA is bowing to industry pressure, the energy industry has long claimed that the government has its science wrong. Some Republican members of Congress have publicly agreed. Commenting on the latest news, Louisiana senator David Vitter is quoted as saying, "The EPA has been on a witch hunt to shut down hydraulic fracturing, but yet again the evidence has determined it is safe."

Acting on a request from Congress, the environmental watchdog in November 2011 said it would seek to clarify the effects of fracking on water resources. In March 2013, it appointed a review panel for a study due to be released in 2014. Unconfirmed reports suggest that completion may be delayed. Whatever the outcome, the EPA is not thought likely to recommend a ban on shale gas extraction.