Methane concentrations in drinking water wells near natural gas drilling sites in the Marcellus shale region of Pennsylvania and New York are 17 times higher, on average, than concentrations of this gas in drinking water wells in areas without any drilling, a study published today in the Proceedings of the National Academy of Sciences concludes.
“At least some of the homeowners who claim that their wells were contaminated by shale-gas extraction appear to be right," said one of the authors, Robert B. Jackson of Duke University.
Drilling industry representatives have long argued that hydraulic fracturing for natural gas has not caused a single verified case of drinking water contamination -- a claim that has been contested by residents of Dimock, Pennsylvania, and elsewhere, who say they have evidence of polluted drinking water.
The study released today provides evidence of methane contamination of drinking water, but not contamination from chemial compounds, such hydrochloric acid or diesel fuel. As part of the hydraulic fracturing process that shatters rock to release natural gas, these chemicals are mixed with millions of gallons of water and sand and injected by drilling companies a mile or more into the ground. The process produces wastewater that can contain both chemicals and high salt concentrations. Environmentalists have been concerned that this wastewater is sometimes spilled or released only partially treated into streams and rivers that flow toward the Chesapeake Bay.
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By Tom Pelton
Chesapeake Bay Foundation