The Center for Rural Pennsylvania is a bipartisan legislative agency serving as a resource and research arm for rural policy in the Pennsylvania Assembly and Senate. The Center has just released the results of a study conducted in 2010 and 2011 analyzing the impacts of Marcellus Shale gas drilling on rural drinking water supplies. This was an unbiased, large scale study of water quality in 233 private water wells in rural Pennsylvania before and after the drilling of nearby Marcellus Shale gas wells. The study results are embedded below.
The study found that dissolved methane exists in about 20 percent of private water wells—before drilling begins. In the executive summary, the study concludes:
In this study, statistical analyses of post-drilling versus pre-drilling water chemistry did not suggest major influences from gas well drilling or hydrofracturing (fracking) on nearby water wells, when considering changes in potential pollutants that are most prominent in drilling waste fluids. When comparing dissolved methane concentrations in the 48 water wells that were sampled both before and after drilling (from Phase 1), the research found no statistically significant increases in methane levels after drilling and no significant correlation to distance from drilling. However, the researchers suggest that more intensive research on the occurrence and sources of methane in water wells is needed.
Bottom line: This study shows that fracking does not cause chemical contamination of water wells, and while the authors recommend more study of methane migration, there is no empirical evidence that fracking causes migration of methane into water wells either.