A 30-month state investigation costing more than $900,000 concludes fracking is unlikely to have contaminated drinking water east of Pavillion but leaves many other questions unresolved about the role natural gas operations may have played in polluting the water.
Samples taken from 13 water wells in 2014 detected high levels of naturally occurring pollution. Test results showed little evidence of contaminants associated with oil and gas production.
Those findings, released Friday as part of a report by the state Department of Environmental Quality, come almost four years to the day since the U.S. Environmental Protection Agency released a draft report tentatively linking fracking to polluted water outside this tiny central Wyoming community.
EPA ultimately turned over its investigation to the state in 2013, fearing, as a Star-Tribune report later showed, that it could not defend its initial conclusion.
The DEQ report left several key questions unresolved. While fracking was ruled out as a likely source of contamination, the DEQ report did not completely exonerate Encana Corp., the Canadian company that operates the Pavillion gas field.
Regulators said more research is needed to determine if gas wells have served as a pathway for contaminants reaching drinking water sources. And they noted additional examination is needed of disposal pits in the area, where drilling mud and cuttings have been stored for decades and could have leaked into the groundwater.
But in a sign of Pavillion's complexity, they said the area's unique geology might also be to blame. Pavillion's gas bearing formations are shallow, permeable and relatively close to formations that produce drinking water.
Noncommercial quantities of gas were detected in the shallower geologic zone where water wells are drilled, regulators noted.
And there is evidence of a naturally occurring buildup of gas in the area's sandstone formations, which may have seeped upward into the water-bearing rock.
"A lack of baseline water-quality data that predates development of the Pavillion Gas Field hinders reaching firm conclusions on causes and effects of reported water-quality changes potentially due to gas exploration and production operations," the report said.
Pavillion has been a political hot potato ever since some residents started reporting problems with their water in the early 2000s. DEQ initially declined to investigate the cause, prompting some residents to take their concerns to the EPA.
The federal agency's preliminary conclusion that fracking was to blame quickly rose to the forefront over the safety of the practice. Industry representatives, state regulators and congressional Republicans said EPA lacked the evidence to support its conclusion and questioned the agency's testing methods.
Doubts have plagued Wyoming's inquiry ever since it assumed responsibility for the investigation in 2013. Encana paid $1.5 million to help cover the cost of the state's analysis, drawing criticism from environmentalists and some Pavillion landowners.
And experts have questioned the state's decision not to drill groundwater monitoring wells, saying they are necessary to pinpoint the source of contamination.
A recent Star-Tribune investigation found Wyoming regulators once considered the possibility of drilling monitoring wells but ultimately concluded they would be expensive and decided more investigation was needed to determine if their installation was warranted.
Critics and supporters of the state's approach were still reviewing the draft report when reached Friday.
"No evidence suggests a link was found between hydraulic fracturing operations in the field and the reported palatability concerns," Encana spokesman Doug Hock wrote in an email.
Jeff Locker, a Pavillion landowner who is suing Encana on a claim its operations are responsible for the deterioration of his wife's health, said he had little confidence in the state's investigation. State regulators found levels of 2-ethylhexyl phthalate above drinking water standards but attributed them to laboratory contamination, he noted.
"They try to find anything it can’t be instead of what it probably is," Locker said.
The report, prepared for DEQ by Acton Mickelson Environmental of El Dorado Hills, California, was reviewed by an independent third party, Veridian Environmental, prior to its release. State officials said that of the 11,700 analytical results reviewed, only eight were rejected.
The public will now have 90 days to comment on the draft findings. While the draft recommends potential next steps, including the possible installation of groundwater monitoring wells, no firm decisions will be made until after the public comments are received and considered, said DEQ Director Todd Parfitt.
He said there is no timeline for finalizing the report after public comments are received.
The report released Friday was the last of three studies called for under an agreement the state reached with EPA when Wyoming took over the investigation.
The two initial studies completed by Oil and Gas Conservation Commission looked into the integrity of Pavillion's gas wells and the 92 disposal pits scattered across the small natural gas field east of town. Neither came to firm conclusions, and each said more study was needed.
DEQ's study said there was little evidence that the fluids used to frack wells had reached depths where they could interact with shallow groundwater.
Samples did show concentrations of naturally occurring salts, metals and radionuclides in excess of drinking water standards. Tests results also recorded concentrations of a pesticide and 2-ethylhexyl phthalate in excess of safety standards.
Low levels of petroleum constituents were detected in the water, which the report said could be attributable to surface spills from fueling trucks or gas well pits.
But perhaps the biggest question concerns potential pathways between the water and gas-bearing zones.
The report noted gaps in the surface casing and cement enclosing some wells may have served as a conduit for gas to reach drinking water sources. But gas found at shallower depths could also be naturally occurring, it said.
The study recommended assessing the wells to determine if they were responsible for upward gas seepage.
"We don’t know how significant that is. We’re suggesting that we look at it a little more closely to see if we can quantify it and to see if it is an actually an issue of concern or not," said Kevin Frederick, director of DEQ's Water Quality Division.