(a) On December 22, 2009, David L. Klemp, Bureau Chief, Air Resources Management Bureau, of the Montana Department of Environmental Quality submitted a certification letter which provides the State of Montana's SIP provisions which meet the requirements of CAA Section 110(a)(1) and (2) relevant to the 1997 Ozone NAAQS.

(b) On February 10, 2010, Brian Schweitzer, Governor, State of Montana, submitted a certification letter which provides the State of Montana's SIP provisions which meet the requirements of CAA section 110(a)(1) and (2), elements (A), (B), (C) with respect to the requirement to have a minor NSR program that addresses PM2.5; (E)(i), (E)(iii), (F), (G), (H), (J) with respect to the requirements of sections 121 and 127, (K), (L), and (M).

(c) On September 26, 2018, Steve Bullock, Governor, State of Montana, submitted a certification letter which provides the State of Montana's SIP provisions which meet the requirements of CAA section 110(a)(1) and (2) relevant to the 2015 8-hour Ozone NAAQS.