Hydraulic fracturing facility in Rifle, Colo.Far be it from the Environmental Protection Agency to admit it was wrong — but late last week, it subtly withdrew from a once-flashy investigation regarding whether hydraulic fracturing contaminated groundwater in the tiny town of Pavillion, Wyo. Never has backpedaling been such an effective form of transportation. In December 2011, the EPA released a draft report of a study it conducted in Wyoming, eliciting a furor of media attention. The New York Times reported that “chemicals used to hydraulically fracture rocks in drilling for natural gas in a remote valley in central Wyoming are...