(a) The State of Montana added the Interstate Transport Rule Declaration to the State SIP, State of Montana Air Quality Control Implementation Plan, Volume I, Chapter 9, to satisfy the requirements of Clean Air Act Section 110(a)(2)(D)(i) for the 8-hour ozone and PM_2.5 NAAQS promulgated in July 1997. The Montana Interstate Transport Rule Declaration, adopted and effective on the same date of February 12, 2007, was submitted to EPA on April 16, 2007. The April 16, 2007 Governor's letter included as an attachment a set of dated replacement pages for the Montana Interstate Transport Rule Declaration. The new set of pages were sent as replacement for the set of undated pages submitted earlier with the February 12, 2007 Record of Adoption package. In a May 10, 2007 e-mail to Domenico Mastrangelo, EPA, Debra Wolfe, of the Montana Department of Environmental Quality, confirmed February 12, 2007 as the adoption/effective date for the Montana Interstate Transport Rule Declaration.

(b) On February 10, 2010, Montana Governor Brian Schweitzer submitted a letter certifying, in part, that Montana's SIP is adequate to meet the interstate transport requirements of CAA section 110(a)(2)(D)(i)(I) for the 2006 PM_2.5 NAAQS.

(c) EPA is approving both elements of CAA section 110(a)(2)(D)(i)(I) for the 2008 ozone NAAQS, which was submitted to EPA on January 3, 2013.

(d) EPA is approving the Montana 2012 PM_2.5 NAAQS Infrastructure Certification, submitted to EPA on December 17, 2015, for both elements of CAA section 110(a)(2)(D)(i)(I) for the 2012 PM_2.5 NAAQS.

(e) EPA is approving the Montana 2010 SO₂ NAAQS Infrastructure Certification, submitted to EPA on July 15, 2013, for both elements of CAA section 110(a)(2)(D)(i)(I) for the 2010 SO₂ NAAQS.