(June 13, 2016, 10:24 AM EDT) -- WASHINGTON, D.C. — A nonprofit environmental advocacy group on June 8 filed a complaint and a request for an investigation with the inspector general of the U.S. Environmental Protection Agency, contending that, based on accounts provided by a whistle-blower, there has been “a persistent and deliberate cover up” at the EPA with regard to information about methane emissions connected to hydraulic fracturing. Moreover, the group argues that the studies relied upon by the EPA to develop policies and regulations were “scientifically invalid.”...