Industry officials insist the process is safe. But the new Texas study notes a concern among scientists about the lack of hard data on the drilling boom's potential environmental effects.
"Despite a number of recent investigations, the impact of natural gas extraction on groundwater quality remains poorly understood," the Texas study said.
Another study, published in May by the journal Science, found that, "It is difficult to determine whether shale gas extraction in the Appalachian region since 2006 has affected water quality regionally, because baseline conditions are often unknown or have already been affected by other activities, such as coal mining."
Last week, The Associated Press reported on what it said were the "preliminary" results of a U.S. Department of Energy study that found "no evidence" that drilling chemicals contaminated drinking water aquifers near at a western Pennsylvania site. The study marks the first time that a drilling company has allowed government scientists to inject special tracers into fracking fluid to monitor if the chemicals spread toward drinking water sources.
Shelley Martin, a spokeswoman for DOE's National Energy Technology Laboratory, later told the Gazette, "While nothing of concern has been found thus far, the results are far too preliminary to make any firm claims."
"We are still in the early stages of collecting, analyzing and validating data from this site," Martin said in an email earlier this week. "We expect a final report on the results by the end of the calendar year."
Martin did not respond to a follow-up request for data from the "preliminary" results or for an interview with the scientists involved in the study.
In West Virginia, business and political leaders are eager to expand natural gas drilling, to tap into the vast reserves contained in the Marcellus Shale, a formation that stretches from southern New York and into eastern Ohio.
Between 2003 and 2011, West Virginia's natural gas production more than doubled to nearly 400 million cubic feet. Over roughly the same period, employment in the industry increased by 55 percent, to more than 10,000.
The Obama administration has embraced shale-gas drilling, with the president saying in a major speech last month that natural gas is "the transition fuel that can power our economy with less carbon pollution" as the nation moves toward "the even cleaner energy economy of the future."
Obama acknowledged that more needs to be done to make natural gas drilling safe, and noted the need for better control leaks of the potent greenhouse gas methane from gas production.
At the same time, EPA has backed off major investigations of drilling impacts on water quality in Wyoming, Pennsylvania and Texas, and the agency doesn't plan to issue a draft of a nationwide study of the issue until late 2014.
Reach Ken Ward Jr. at kw...@wvgazette.com or 304-348-1702.