Approval and Promulgation of Air Quality Implementation Plans; Iowa; Regional Haze Five-Year Progress Report State Implementation Plan

The Environmental Protection Agency (EPA) is issuing a supplement to its proposed approval of a State Implementation Plan (SIP) revision submitted by the State of Iowa (Iowa) through the Iowa Department of Natural Resources (IDNR). Iowa's SIP revision addresses requirements of the Clean Air Act (CAA) and EPA's rules that require states to submit periodic reports describing progress toward reasonable progress goals established for regional haze and a determination of the adequacy of the state's existing implementation plan addressing regional haze (region haze SIP). EPA's proposed approval of Iowa's periodic report on progress toward reasonable progress goals and determination of adequacy of the state's regional haze SIP published in the Federal Register on July 3, 2014. This supplemental proposal addresses the potential effects on our proposed approval from the April 29, 2014, decision of the United States Supreme Court (Supreme Court) remanding to the United States Court of Appeals for the District of Columbia Circuit (D.C. Circuit) EPA's Cross-State Air Pollution Rule (CSAPR) for further proceedings and the D.C. Circuit's decision to lift the stay of CSAPR.