In the past decade, hydraulic fracturing (“fracking”) has increased dramatically in the Marcellus Shale region, which stretches over parts of Pennsylvania, Maryland, Virginia, West Virginia, Ohio, and New York. Fracking and related activities (mixing fracking fluids, transporting chemicals and wastewater, disposing of wastewater) have the potential to pollute surface water in a variety of ways, but it remains unclear how widespread a problem such pollution may be. Thus, the goal of this project was to assess whether geographic correlations exist between fracking in the watershed and significant differences in stream water quality. The geographic focus was the Potomac River watershed, which is Washington, D.C.’s water source. A small percentage of the Potomac watershed lies in West Virginia, where fracking has been occurring on an industrial scale since 2000, while the majority lies in Maryland and Northern Virginia, where no fracking has yet occurred. In summer 2015, 73 sites, mainly small streams but also including samples from the main stem of the Potomac and its major tributary the Shenandoah River, were sampled, and in summer 2016 an additional 15 sites in West Virginia were sampled. Parameters measured included specific conductance, pH, sulfate, 223Ra, 224Ra, 226Ra, and 228Ra, Rn, Al, Ba, Cr, Fe, K, Mg, Mn, Na, and Sr.
Results/Conclusions
Mean and median concentrations of 224Ra, Sr, Al, and sulfate in surface water as well as 226Ra in sediment were significantly elevated in areas downstream of a fracking well when compared to areas without a well. When comparing results on a state-by-state level, Virginia, a region without fracking, was found to have significantly lower mean and median levels of Sr, 224Ra, and 226Ra than both Maryland and West Virginia. Sr isotope analysis did not indicate a significant difference in mean 87Sr/86Sr between the states but several sites concentrations in West Virginia were within the ranges expected of produced waters from the fracking process. One abnormally high isotope ratio was found in Maryland. This study primarily analyzed geographic correlations, there are a number of other potential explanations of these results such as extractive industry history. This study is the first to suggest that fracking and related activities are associated with widespread, statistically significant differences in stream water quality. Future research should investigate whether these patterns hold in other important watersheds affected by fracking and explore the specific mechanisms of pollution transport.