John Hanger, secretary of the Pennsylvania Department of Environmental Protection, said late last week he had seen no evidence that hydraulic fracturing (hydrofracking) chemicals used to drill for shale gas contaminate underground water supplies.

"It's our experience in Pennsylvania that we have not had one case in which the fluids used to break off the gas from 5,000 to 8,000 feet underground have returned to contaminate ground water," Hanger told Reuters in an interview.

However, DEP has found cases of water contamination on the surface that were caused by hydrofrack chemical spills and leaks, and there have been cases of water contaminated by methane migration from gas wells, Hanger told the news service.

Cabot Oil & Gas Corp., he said, drilled faulty wells near Dimock, PA, which caused methane to migrate into private water wells (see Daily GPI, Oct. 1).

"There's a lot of focus in the media and the public on the problems that we have not had," he said during the interview. He called Cabot's challenge to DEP's findings "riddled with errors and incredibly unfortunate."