The Chicago Tribune has an article reporting on recent test results showing that groundwater contamination claims are linked to shallow, naturally occurring methane and not the producer's operations: "The analysis, a form of chemical fingerprinting, studies stable isotopes in the methane for signs of its origin.The procedure has become a frequent tool for regulators and companies seeking to distinguish between deep gas harvested by drillers, shallow gas caused by the breakdown of organic material and gas trapped in middle rock layers closer to the surface than the mile-deep Marcellus. *** Susan Oliver, a spokeswoman for WPX, said in an email that 'the characteristics of the methane in the three water wells match the characteristics of the shallow methane that has been in Franklin Forks and the Salt Springs area for many decades. The results do not match the chemical footprint of the natural gas coming from the Marcellus Shale.'"
Don't expect that to end the issue, though ...