The U.S. Environmental Protection Agency said on Friday there is no evidence that hydraulic fracturing contaminated private water wells in rural Pennsylvania.

The EPA's verdict is that private water sources in the town of Dimock, to the northeast of the state, do not show levels of contaminants that warrant further concern.

This set of sampling did not show levels of contaminants that would give EPA reason to take further action, the agency said. At one well, EPA found elevated levels of arsenic and offered alternate water but the resident declined.

The agency's latest announcement upholds two previous assessments that assured residents their water is potable and safe to use. So far the agency has released data for 47 of 60 wells tested.

The EPA's determination upholds similar statements made by Cabot Oil & Gas Corp., (NYSE: CBT) and the Pennsylvania Department of Environmental Protection since November 2011.

The data released today confirms the two earlier EPA findings that levels of contaminants found do not [constitute] a threat to human health and the environment, said Cabot Oil in a statement. Again, these findings are consistent with literally thousands of pages of water quality data accumulated by state and local authorities and by Cabot Oil and Gas.

Some local residents have tried since 2008 to hold Cabot Oil & Gas accountable for the alleged contamination of their private water wells.

Dimock has been on the front lines of the national debate surrounding hydraulic fracturing, or fracking, a drilling technique that calls for the blasting of millions of gallons of water and toxic drilling chemicals to extract natural gas from fractured rocks.

The drilling technique has been heavily criticized, and activists and environmentalists contend fracking contaminates ground water. The EPA is continuing a separate investigation into similar accusations in Pavillion, Wyoming.

The EPA's announcement is a victory for natural gas and oil companies, as the EPA's investigation could act as a barometer for the future of the industry elsewhere.

Oil and natural gas companies are actively buying up leases in Ohio, and Illinois, and by year's end, New York could be the latest state to allow fracking.