The EPA, in a draft report based on a detailed, four-year review, said that although so-called fracking operations “have not led to widespread, systemic impacts on drinking water resources, there are potential vulnerabilities in the water lifecycle that could impact drinking water.” Los Angeles Times. 5 June 2015.
http://www.latimes.com/nation/la-na-sej-fracking-water-epa-20150604-story.html (subscription)