In a significant reversal, the Environmental Protection Agency struck from a major 2015 report its conclusion that fracking has not caused “widespread, systemic impacts on drinking water” in the United States. The agency cited the lack of data and evidence to support the finding.

The change was made after an EPA panel of independent scientists recommended in August that the agency revise the statement, which had minimized the potential hazards posed to drinking water. The panel, known as the Science Advisory Board (SAB), spent a year analyzing the draft version of the study.

In a call with reporters, Thomas A. Burke, the EPA’s deputy assistant administrator and science adviser, said the SAB’s analysis was central to the change.

“The Science Advisory Board recommended that EPA quantitatively support this conclusion” that fracking did not pose a threat to drinking water, Burke said. “Significant data gaps and uncertainties limited our ability to estimate the national frequency of impacts.  Consequently, EPA scientists concluded that the sentence could not be quantitatively supported.”

When it was issued in June 2015, the 1,000-page draft EPA water and fracking study confirmed for the first time that fracking in some instances had contaminated drinking water. Successive EPA officials, under Democratic and Republican presidents alike, had denied until then that fracking could affect drinking water.

Nonetheless, the top-line finding in the initial draft report said the agency did not find evidence that the mechanisms of possible contamination were widespread or inherent to the process.

The new final version does not conclude that there is widespread pollution of drinking water, cautioned Robert Jackson, professor of environment and energy at Stanford University. The available data do not support that either. Rather, the report helps to characterize and assess risk throughout the fracking process, from the withdrawal of water to be mixed with chemicals, through the mixing stage, injection of fracking fluid into an oil or gas well, handling of the water that returns up the well and the eventual disposal of the waste.

“These activities can impact drinking water resources under some circumstances,” the report said.

“Cases of impacts were identified for all stages of the hydraulic fracturing water cycle,” it continued. “Identified impacts generally occurred near hydraulically fractured oil and gas production wells and ranged in severity from temporary changes in water quality to contamination that made private drinking water wells unusable.”

Jackson said the new report more closely reflects what other fracking research has found. “The revised summary much more accurately captures the content of the original report and the state of science today,” he said. “Fracking writ large doesn’t usually contaminate water but it has and the report acknowledges different ways that that happens.”

When the draft water study was issued last year, the oil and gas industry seized upon the original conclusion to back its contention that fracking does not pose a threat to water.  It has long argued that there has never been a case of water contamination related to fracking, despite evidence to the contrary, including by the EPA.

The EPA’s reversal drew angry condemnation from the oil and gas industry, which continued to embrace the original finding.  

“It is beyond absurd for the administration to reverse course on its way out the door,” Erik Milito, the American Petroleum Institute upstream director, said in a statement. “Decisions like this amplify the public’s frustrations with Washington.” 

The Environmental Defense Fund, which has often worked with oil and gas companies to assess the public health risks of fracking, said the final version is more accurate.

“EPA’s initial draft misled the public about the pollution risks of unconventional oil and gas development,” said Mark Brownstein, EDF’s vice president of climate and energy. “The revised assessment puts an end to the false narrative of risk-free fracking that has been widely promoted by industry. It opens the door for policy improvements and scientific advancements that could better protect the people and places most impacted.”

Fracking has expanded so swiftly in the last decade that it accounted for 50 percent of U.S. oil production and 70 percent of natural gas production in 2015, the EPA study said, citing Energy Department data. About 300,000 of the 1 million fracked oil and gas wells in the U.S. underwent the process between 2000 and 2014.

The increased use of fracking has moved it closer to more Americans and their drinking water, according to the report.  Now, about 3,900 public water systems are within a mile of a fracked well, and they serve about 8.6 million people, the report said. Another 3.6 million people have private water wells in counties with at least one fracked well.  

The median water use at an oil or gas well is 1.5 million gallons each time it is fracked, the frequency varying with the well.

The greater proximity of fracking to drinking water and several well-publicized incidents of possible contamination spurred calls for the EPA examine its impact on water resources.

The EPA study, requested by Congress, was supposed to provide critical information about fracking’s safety “so that the American people can be confident that their drinking water is pure and uncontaminated,” a top EPA official said at a 2011 hearing.

In the final report, the EPA said gaps and uncertainties in available data “prevented us from calculating or estimating the national frequency of impacts on drinking water sources.”

As a result, the final report does not define the scope of damage to drinking water. Instead it provides information about circumstances when water is most likely to get tainted, as lessons for communities, industry and regulators to consult as they decide to proceed with fracking.

“It does a good job of describing the mechanisms where things have gone wrong, not in principle but in practice. That’s important to learn from to keep it from happening in different locations,” Jackson said.

The report does not call for new regulations or identify the best practices to prevent water contamination.

Still, industry characterized the revised conclusions as politically-motivated appeasement of environmentalists by the Obama administration. That’s despite the year-long review by independent scientists at the SAB, which included those from the oil and gas industry. API’s Milito voiced hope the report would be discarded by the incoming Trump administration, which has expressed its disdain for environmental rules and is eager to expand oil and gas extraction.

Said Milito, “We look forward to working with the new administration in order to instill fact-based science back into the public policy process.”