Pennsylvania has three of the seven sites picked by the U.S. Environmental Protection Agency (EPA) to study the potential effects of fracking on drinking water. The sites are in Bradford County in the Northern Tier, Susquehanna County in the northeast and Washington County in the southwest.

EPA spokesperson Mollie Lemon summarized the investigations in a recent email:

"EPA has selected seven case studies that the Agency believes will provide the most-useful information about the potential impacts of hydraulic fracturing on drinking water resources under a variety of circumstances. The information we gather from these case studies will be part of an approach which includes literature review; collection of data and information from states, industry and communities; laboratory work; and computer modeling. The combination of these materials will allow us to do a more comprehensive assessment of the potential impacts of hydraulic fracturing on drinking water resources.

Two sites are prospective case studies where EPA will monitor key aspects of the hydraulic fracturing process at future hydraulic fracturing sites. They are located in:

  • Haynesville Shale: DeSoto County, La. (Chesapeake Energy)
  • Marcellus Shale: Washington County, Pa. (DOE and Range Resources)

The five retrospective case studies, which will focus on possible drinking water contamination due to hydraulic fracturing operations at existing sites, are located in:

  • Bakken Shale: Kildeer and Dunn Counties, N.D.
  • Barnett Shale: Wise and Denton Counties, Texas
  • Marcellus Shale: Bradford and Susquehanna Counties, Pa.
  • Marcellus Shale: Washington County, Pa.
  • Raton Basin: Las Animas County, Colo.

More information on the key issues being investigated and what is anticipated to be learned at each of the retrospective site can be found at: http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/case_studies.cfm.

The case studies were identified, prioritized and selected based on rigorous criteria and site visits by EPA scientists who will be conducting the research. Decision criteria include proximity of population and drinking water supplies, evidence of impaired water quality (retrospective only), health and environmental concerns (retrospective only) and knowledge gaps that could be filled by the case study. Sites were prioritized based on geographic and geologic diversity, population at risk, site status (planned, active or completed), unique geological or hydrological features, characteristics of water resources and land use."