When Congress first tasked the Environmental Protection Agency in 2009 with studying the impacts of hydraulic fracturing on drinking water resources, pundits on both sides of the debate collectively held their breath: at last, they thought, there would be an independent, comprehensive, scientific study of the oil and gas extraction technique.

Seven years in the making, EPA’s final report, dubbed, “Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the United States,” (EPA-600-R-16-236ES) and issued December 13, was greeted not with a bang, but a whimper. Environmentalists who had hoped that the study might represent a scathing indictment of the technique were disappointed, as were industry representatives who hoped that the EPA would issue an unassailably clean bill of health.

Hampered by an uncertain budget and its failure to secure the participation of private companies in prospective case studies, the EPA concluded, seemingly unremarkably, that activities throughout the hydraulic fracturing water cycle – from water withdrawal through disposal of produced water – “can impact drinking water resources under some circumstances.” But, the agency said, it could not quantify the frequency of impacts on a national level.

In addition to finding that spills of hydraulic fracturing chemicals had sometimes reached drinking water resources, the EPA also identified incidents of the well injection process itself contaminating drinking water resources. One such incident resulted from improper well cementing, while another stemmed from a burst production casing.

The final assessment clarifies the findings in the agency’s June 2015 draft final report. There the EPA concluded that it had not found “evidence that these mechanisms have led to widespread, systemic impacts on drinking water resources in the United States.” Industry greeted this conclusion enthusiastically, while environmentalists and others cried foul.

Last August the agency’s own Science Advisory Board (SAB) sharply criticized the statement as unsupported by the data and not reflective of the significant data gaps in the agency’s research. The SABspecifically faulted the EPA’s failure to provide updates on allegations of drinking water contamination in Pavillion, Wyoming, Parker County, Texas and Dimock, Pennsylvania – the small town at the center of the 2010 documentary Gasland which featured now infamous scenes of homeowners setting tap water alight.

The final report relegates discussion of these high-profile matters to three brief text boxes, which collectively reflect uncertainty in determining the precise source and mechanism of contamination and suggest that additional data may be available that would allow other researchers to draw more certain conclusions.

While the 666-page report said little about Pavillion, Parker County and Dimock, the EPA researchers concluded that six hydraulic fracturing activities are “more likely than others to result in more frequent or more severe impacts” to drinking water: water withdrawals; chemical spills; injection of fluids into wells with inadequate mechanical integrity; injection of fluids directly into groundwater; inappropriate discharge of fracturing wastewater into streams and lakes; and storage of fracturing wastewater in unlined pits.

While the EPA could not pinpoint the overall incidence of impacts, the report contains some clues. Regarding well integrity, for example, the EPA found that in 0.5% of the 28,500 hydraulic fracturing jobs it surveyed, “all of the protective barriers intended to prevent [ ] fluid migration had failed, leaving the groundwater source vulnerable to contamination.” Chemical spills, meanwhile, ranged from about 0.4 to 12.2 reported spills per 100 wells. While those numbers may seem modest, they, along with documented impacts, nevertheless contravene the pre-study message that there were no known cases of drinking water contamination stemming from hydraulic fracturing.

In a different political environment, regulators might have relied on these numbers to support additional rulemaking at the federal level to protect drinking water resources from hydraulic fracturing impacts. The incoming Trump administration, however, has made no secret of its disdain for EPA and its regulations on fossil fuel production and use. Absent an environmental catastrophe, new federal requirements on hydraulic fracturing are highly unlikely.

More than ever, regulation of these activities will fall to the states. For now, though, with oil and gas prices at or near historic lows – and with a continuingly cooled pace of oil and gas exploration and production activities – states may be loath to issue new regulations or take aggressive enforcement action.