The Environmental Protection Agency has concluded the drilling practice of hydraulic fracturing is mostly safe for the nation’s water supply. A multi-year study says there’s no evidence fracking has had “systemic impacts on drinking water resources” nationwide. But the EPA does say fracking techniques have contaminated water in some cases and have “the potential to impact drinking water resources.” Environmental groups say the study overly relied on energy companies’ data. Concerns over contamination have led to fracking bans in Maryland and New York.