Starting in 2008, ProPublica published stories that found hydraulic fracking had damaged drinking water supplies across the country. The reporting examined how fracking in some cases had dislodged methane, which then seeped into water supplies. In other instances, the reporting showed that chemicals related to oil and gas production through fracking were winding up in drinking water, and that waste water resulting from fracking operations was contaminating water sources.

Many environmentalists hailed the reporting. The gas drilling industry, for its part, pushed back, initially dismissing the accounts as anecdotal at best.

This week, the Environmental Protection Agency issued its latest and most thorough report on fracking’s threat to drinking water, and its findings support ProPublica’s reporting. The EPA report found evidence that fracking has contributed to drinking water contamination — “cases of impact” — in all stages of the process: water withdrawals for hydraulic fracturing; spills during the management of hydraulic fracturing fluids and chemicals; injection of hydraulic fracturing fluids directly into groundwater resources; discharge of inadequately treated hydraulic fracturing wastewater to surface water resources; and disposal or storage of hydraulic fracturing wastewater in unlined pits, resulting in contamination of groundwater resources.

In an interview, Amy Mall, a senior policy analyst at the National Resources Defense Council, said the EPA’s report was welcome.

“Many of us have been working on this issue for many years, and industry has repeatedly said that there is no evidence that fracking has contaminated drinking water,” Mall said.

The EPA report comes a year after its initial set of findings set off fierce criticism by environmental advocates and health professionals. That report, issued in 2015, said the agency had found no evidence that fracking had “led to widespread, systemic impacts on drinking water resources.” Many accused the agency of pulling its punches and adding to confusion among the public. News organizations throughout the U.S. interpreted the EPA’s language to mean it had concluded fracking did not pose a threat to water supplies and public health.

The EPA said in its report this week that the sentence about the lack of evidence of systemic issues had been intentionally removed because the agency’s scientists had “concluded it could not be quantitatively supported.”

“I think one of the concerns about the original document was that the EPA seemed to say that everything was fine,” said Rob Jackson, a professor of earth-system science at Stanford University. “It’s important that we understand the ways and the cases where things have gone wrong, to keep them from happening elsewhere.”

The EPA’s latest declaration comes as a Trump administration apparently hostile to almost any kind of regulation of fracking prepares to assume office. But those worried about fracking’s implications for the environment have long been discouraged by the lack of consistent and stringent state or federal regulation.

“Because state regulators have not fully investigated cases of drinking water contamination, and because federal regulators have been handcuffed by Congress into how much they can regulate, the science wasn’t as robust as it should have been,” said Mall, the analyst at NRDC. “It’s a pattern of, the rules are too weak, and the ones that are on the books aren’t enforced enough.”

The more significant impact of a Trump administration, however, may be in limiting the EPA’s appetite for aggressive and continued study. The report issued this week was six years in the making, but made clear there was still much work to be done to better and more comprehensively determine fracking’s impact on the environment, chiefly water supplies.

“It was not possible to calculate or estimate the national frequency of impacts on drinking water resources from activities in the hydraulic fracturing water cycle or fully characterize the severity of impacts,” the report said.

The Trump administration’s transition team did not immediately respond to an e-mailed request for comment about its position on fracking and the EPA’s final report. Trump’s transition website promises to “unleash an energy revolution” and “streamline the permitting process for all energy projects.” It also says it will “refocus the EPA on its core mission of ensuring clean air, and clean, safe drinking water for all Americans.”

Advocates for hydraulic fracturing argue that the final EPA report is not vastly different from the draft version.

“Anecdotal evidence about localized impacts does not disprove the central thesis, which is that there is no evidence of widespread or systemic impacts,” said Scott Segal, a partner at Bracewell LLP who represents oil and gas developers. “There’s a lot of exaggeration. There’s a lot of mischaracterization of the extent of contamination that’s based on a desire to enhance recovery in tort liability lawsuits.”

Read more of ProPublica’s major work on fracking.