The Environmental Protection Agency announced Thursday that fracking may be to blame for causing groundwater pollution. The controversial method of improving the productivity of oil and gas wells has been a source of debate across the country. The E.P.A. found that compounds likely associated with fracking chemicals had been detected in the groundwater beneath Pavillion, a small community in central Wyoming where residents say their well water reeks of chemicals. Health officials last year advised them not to drink their water after the E.P.A. found low levels hydrocarbons in their wells. Tristan Ahtone is reporter for Wyoming Public Radio who has been covering this story from Laramie, Wyoming.