GSP Merrimack L.L.C. owns and operates Merrimack Station, a coal-fired, steamelectric power plant located in Bow, New Hampshire. In May 2020, the U.S. Environmental Protection Agency Region 1 (“Region”) reissued a final National Pollutant Discharge Elimination System (“NPDES”) permit to GSP Merrimack, pursuant to section 402 of the Clean Water Act, 33 U.S.C. § 1342, authorizing it to continue withdrawing cooling water from and discharging pollutants, including heated wastewater, to the Merrimack River.