Wyoming environmental regulators on Monday upheld a long-standing determination that exploration and production (E&P) activity was not the cause of drinking water contamination in the town of Pavillion, as federal regulators alleged more than a decade ago.

Wyoming’s latest pronouncement confirmed the state’s conclusion in 2016 that gas drilling activity, and specifically hydraulic fracturing, did not contaminate Pavillion’s water.

The 4,200-page report was developed by the Department of Environmental Quality’s water quality division, ending a saga that began more than a decade ago when the U.S. Environmental Protection Agency (EPA) concluded that at least three contaminated water wells near Pavillion contained a hydraulic fracturing chemical used by natural gas drillers.

The report presents the findings of additional sampling of water recommended with the 2016 report, which ruled out E&P culpability.

The report is to be subsequently reviewed by the Wyoming Oil and Gas Conservation Commission.

DEQ applied improved technology since 2016 to again rule out the presence of any critical compound or bacteria that might have been missed. EPA formally abandoned its work in Pavillion in 2013.

DEQ sampled 13 water supply wells with funds from a former operator at Pavillion, Encana Corp., and the state legislature later applied nearly $1 million to supply 28 area landowners with clean water.