SHALE-GAS IMPACTS IN PENNSYLVANIA SURFACE WATERS

High-volume hydraulic fracturing (HVHF) has changed the energy economy worldwide by enabling the extraction of gas from low-permeability shale formations. At the same time, the use of HVHF to extract shale gas has sometimes impacted surface and ground waters. Some of these incidents have resulted in considerable public pushback in some localities. In the Marcellus shale-gas play in Pennsylvania (PA), the most common impacting contaminant is methane. Methane sometimes leaks out of gas wells from the target shale or from surrounding formations and enters aquifers. Upwelling ground water can then bring this contaminating methane into surface waters. Other contaminants that have also been identified in ground and surface waters and derived from unconventional or conventional gas industry operations include salts, metals, radioactive contaminants, and organic compounds derived from fracking fluids, drilling fluids, or the shale and its formation waters. Data we have compiled in the Shale Network database (doi:10.421/his-data-shalenetwork) show that the most likely pathway for contaminants other than methane to enter surface waters is through spills or leaks – not through upwelling of fluids. However, publicly accessible data show impacts on surface waters for only a few of the approximately 45 major contaminant spills in PA related to shale-gas development since 2004. Thus, analysis of publicly available surface water data for PA in the area of shale-gas development reveals relatively few environmental incidents of significant impact compared to wells drilled ... but such impacts are difficult to assess due to the lack of transparent and accessible data. For example, some data are not released publicly while others are not maintained in user-friendly online databases. Another aspect of this problem is that monitoring surface waters for such impacts is expensive and time-consuming: designing an efficient monitoring network is almost impossible given the site density necessary for complete coverage and the density of drilled shale-gas wells. The best approach may be to develop partnerships among scientists, citizen scientists, industry personnel, and third-party "honest brokers" to enable the public access to the data needed to decide to extend (or not) the social license of fracking.