The leading federal research effort into the controversial drilling method known as fracking has turned up no evidence so far linking the process to water contamination — a connection continually drawn by many environmentalist critics along with some Democrats in Congress.
Department of Energy research, being conducted at a Marcellus Shale natural gas well in western Pennsylvania, thus far has shown that chemicals used in the hydraulic fracturing practice have stayed thousands of feet below drinking-water supplies.
The study was begun about a year ago, but federal officials say final results are still months away.
"We are still in the early stages of collecting, analyzing and validating data from this site. While nothing of concern has been found thus far, the results are far too preliminary to make any firm claims. We expect a final report on the results by the end of the calendar year," says a statement from the department's National Energy Technology Laboratory.
While the study has yet to be finalized, the oil and natural gas industry is seizing on the initial findings. The fracking boom has led to a massive surge in U.S. natural gas supplies and is helping to rewrite the global balance of power among energy suppliers.
Kathryn Klaber, CEO of the Marcellus Shale Coalition, called the study "great news."
"It's important that we continue to seek partnerships that can study these issues and inform the public of the findings," she told The Associated Press.
Ms. Klaber's organization represents companies doing business in the Marcellus Shale, one of the largest known natural gas deposits in the world.
Pennsylvania, particularly towns in the northern and western parts of the state, have reaped enormous economic benefits from the natural gas extracted from the Marcellus.
A similar renaissance in American oil and natural gas production also is taking place in North Dakota and other states across the nation, largely due to the expansion and development of fracking.
But there are many detractors, who say fracking — the use of water, sand and chemicals to crack underground rock and free natural gas — is dangerous for the environment. Specifically, they argue that the practice is inherently harmful to water supplies.
Such claims formed the basis of the recent documentary "Gasland 2," a highly critical look at fracking and its impacts in Pennsylvania and elsewhere.
Recent research from the federal government and state officials, however, indicates that fracking — when done correctly and in line with proper rules and environmental regulations — is safe.
In addition to last week's initial results from the Energy Department, there was an April determination by Pennsylvania investigators that fracking isn't to blame for high methane levels in three families' drinking water in a northern Pennsylvania town.
The federal Environmental Protection Agency also has dropped its plan to have independent, third-party scientists review findings that fracking contaminated groundwater in Pavillion, Wyo.
The EPA says it is standing by its initial findings, but industry leaders painted the decision as proof that the agency knew its science was flawed and its conclusions incorrect.