The Environmental Protection Agency announced Thursday that a popular but controversial method for boosting the productivity of oil and gas wells could be responsible for polluting drinking water.

The finding, included in a draft report, was quickly assailed by the industry. One U.S. senator called it “premature” and politically motivated.
But the EPA said it prepared the report with the safety of residents as its top priority.

The draft finding pertains to a process called “fracking.” The method involves pumping pressurized water, sand and chemicals underground to open up cracks in the rock and in turn improve the flow of fossil fuels.