The Washington Post has a story on a recent study finding that hydraulic fracturing has not contaminated water wells in Arkansas: "Members of the U.S. Geological Survey were also part of the study, which examined 127 drinking water wells for evidence of pollution from methane gas or chemicals. *** The study published Wednesday looked at an area of heavy drilling in north-central Arkansas known as the Fayetteville Shale. More than 4,000 new wells have been drilled there since 2004. The researchers did multiple tests to looks for the presence of contamination from drilling, or from naturally occurring gas or ultra-salty liquids that seep up through pre-existing faults. *** Arkansas homeowners 'typically had good water quality, regardless of whether they were near shale gas development,” said Robert Jackson, a professor of environmental sciences at Duke."
For a copy of the study, see here.