The Incorporated County of Los Alamos, New Mexico (“County”), filed a petition for review (“Petition”) with the Environmental Appeals Board (“Board”) under 40 C.F.R. § 124.19. The Petition seeks Board review of a designation decision by U.S. EPA Region 6 (“Region”) pursuant to section 402(p)(2)(E) of the Clean Water Act (“CWA”), 33 U.S.C. § 1342(p)(2)(E), and 40 C.F.R.