As one of its last official acts, the Obama administration Environmental Protection Agency (EPA) backed away from making a definitive statement on the impacts of hydraulic fracturing, saying it lacked sufficient data to quantify their severity and frequency.

The 1,200-page final report issued December 13, “Hydraulic Fracturing for Oil and Gas: Impacts from the Hydraulic Fracturing Water Cycle on Drinking Water Resources in the United States,” was five years in the making and in many respects became a political football kicked back and forth by the administration, Congress, and outside environmental and fossil-fuel special interest groups. A 2015 draft version of the study noted that that hydraulic fracturing, or “fracking,” had “no widespread, systematic impacts” on water quality.

According to spokesman Thomas Burke, that conclusion drew attention from the EPA’s independent Science Advisory Board, which asked the agency to quantify it. Because EPA scientists were unable to do so because of a lack of data, the conclusion was pulled from the final version, Burke said on a media call.

The report found that fracking can impact water quality under certain circumstances, typically when proper drilling and disposal practices are not followed or spills occur. Those are risks that have been known for years, and the EPA’s mission with the report was to determine how extensive the impacts were.

But after five years, the EPA was unable to do so. “Data gaps and uncertainties limited EPA’s ability to fully assess the potential impacts on drinking water resources locally and nationally,” the abstract to the report says. “Because of these data gaps and uncertainties, it was not possible to fully characterize the severity of impacts, nor was it possible to calculate or estimate the national frequency of impacts on drinking water resources from activities in the hydraulic fracturing water cycle.”

The upshot is to essentially pass the issue on to the administration of President-elect Donald Trump, who has promised to ease regulatory burdens on oil and gas development. Trump’s pick to head the EPA, Oklahoma Attorney General Scott Pruitt, seems likely to block any further efforts to regulate fracking, which means the EPA’s research on the subject may have effectively ended with Tuesday’s report.

—Thomas W. Overton, JD is a POWER associate editor (@thomas_overton, @POWERmagazine).