One researcher who now consults for oil and gas companies and other clients questioned some of the Duke findings.
Fred Baldassare, who worked for the Pennsylvania Department of Environmental Protection for 25 years, said the study doesn’t present an accurate picture of the whole state because the Duke team went to areas where residents had complained about drilling contamination, rather than doing a random sample. Baldassare runs a research company called Eschelon Applied Geosciences.
Baldassare said that overall the Duke researchers “make a case for stray gas migration caused by gas well drilling activity.”
The second water study was published online last week by the U.S. Geological Survey. It found that some Pennsylvania water wells in areas with no nearby drilling are naturally contaminated with high levels of methane. It also found that 85 percent of the samples had radon levels higher than federal safe limits.
One well sample, taken at a hunting club, had such high natural methane levels, it could have been flammable, said hydrologist Ronald Sloto.
“They knew they had a major water quality problem, they didn’t know what it was,” Sloto said.
The USGS took samples from 20 wells in Sullivan County, in northeastern Pennsylvania, in order to establish a pre-drilling baseline for water quality.
Sloto said his study and the Duke paper confirm that pre-drilling water testing is an absolute necessity for homeowners.
“Once you have drilling you can’t get a baseline, it’s too late” to determine if drilling caused water problems or if they were already there naturally, Sloto said.
The Marcellus Shale Coalition, an industry group, had no direct comment on the Duke findings.
“Private water well quality and construction, as well as methane migration, is a longstanding public health issue in Pennsylvania, dating back decades,” CEO Kathryn Klaber said in an email.