Strong concerns in recent years regarding natural gas drilling possibly contaminating local water supplies for the small town of Pavillion, WY, resurfaced recently as a U.S. Environmental Protection Agency (EPA) regional office fired criticism at a Wyoming study last year that concluded gas development activity, including hydraulic fracturing (fracking), had nothing to do with local water problems.

“Several of the conclusory statements in the report regarding fluid movement and potential sources of constituents would benefit from more robust supporting data and information and a discussion of uncertainties,” Martin Hestmark, assistant regional EPA administration in Denver, wrote to Todd Parfitt, director of Wyoming’s Department of Environmental Quality (DEQ). Hestmark hit at various technical details that EPA found missing.

EPA suggests that there were too many uncertainties surrounding health concerns tied to the quality of the domestic well water for Pavillion. EPA wants more discussion of the uncertainties in the report, said Hestmark, whose staff has critiqued the state’s report, “Pavillion Area Domestic Water Wells Draft Final Report and Palatability Study.”

EPA contends that the state should acknowledge that there are limitations to “reaching definitive conclusions about potential health risks” because of an inherent information gap left because nine of 19 organic constituents found in the water supplies don’t have health-related analyses completed on them.

Contrary to earlier federal reports, Wyoming’s DEQ concluded that fracking fluids were not a factor at shallow depths intersecting groundwater supplies at Pavillion, according to a draft final state DEQ report (see Shale Daily, Dec. 22, 2015).

While both inorganic and organic compounds were found above acceptable levels for drinking water, none of the fluids associated with fracking were found to have migrated upward to shallower depths, the state report concluded. Wyoming found that there were levels of pollutants in the water that exceeded health-based comparison values, but “limited supporting evidence” that all of the constituents were present historically and weren’t coming from gas wells in the area.

While DEQ concluded that the groundwater was generally suitable for domestic use, it also acknowledged the exceedances, noting that for the most part they are related to “naturally occurring dissolved salts, metals and radionuclides.”

EPA regional staff has deconstructed the Wyoming DEQ report, and in one instance asked that a conclusion attributed to EPA asserting that most of the water supply wells did not have apparent health concerns be “qualified or omitted.” The EPA observation was made in a public hearing reporting Phase I results of the federal agency’s well testing in Pavillion (see Shale Daily, Dec. 9, 2011).

EPA subsequently backed away from the gas well link to the water contamination conclusion, and the state took the lead two years ago in conducting further tests through DEQ (see Shale Daily, June 24, 2013). In its latest analysis, regional EPA staff said that “there is little historical evidence in existence to support the state’s argument that the pollution is naturally occurring.”

Hestmark said that in recent years, since DEQ took the lead in the investigation of Pavillion water quality, the federal agency has “provided technical resources and assistance” to support the state’s ongoing efforts.

In Hestmark’s letter, EPA again questioned the state’s contention that “almost certainly” part of the methane observed in the local water supply wells was naturally occurring and not the result of gas production. “This conclusion appears to be based solely on limited data,” he said.