(a) On January 7, 2008, James B. Martin, Executive Director of the Colorado Department of Public Health and Environment for the state of Colorado, submitted a certification letter which provides the state of Colorado's SIP provisions for meeting the requirements of CAA Section 110(a)(1) and (2) relevant to the 1997 8-hour ozone NAAQS. The State's 1997 Ozone Infrastructure SIP is approved with respect to the requirements of the following elements of section 110(a)(2) of the CAA for the 1997 8-hour ozone NAAQS: (A), (B), (C), (D)(ii), (E), (F), (G), (H), (J), (K), (L), and (M).

(b) On April 4, 2008 James B. Martin, Executive Director, Colorado Department of Public Health and Environment, provided a submission to meet the infrastructure requirements for the State of Colorado for the 1997 PM2.5 NAAQS. On June 4, 2010, Martha E. Rudolph, Executive Director, Colorado Department of Public Health and Environment, provided a submission to meet the infrastructure requirements for the State of Colorado for the 2006 PM2.5 NAAQS. The State's Infrastructure SIP is approved with respect to the 1997 and 2006 PM2.5 NAAQS with respect to section (110)(a)(1) and the following elements of section (110)(a)(2): (A), (B), (C) with respect to PSD and minor NSR requirements, (E), (F), (G), (H), (J) with respect to PSD requirements and the requirements of sections 121 and 127 of the Act, (K), (L), and (M).

(c) The Colorado Department of Public Health and Environment provided submissions to meet infrastructure requirements for the State of Colorado for the 2008 ozone, 2008 lead, and 2010 NO2 NAAQS were received on December 31, 2012, July 26, 2012, and March 7, 2013, respectively. The State's Infrastructure SIP is approved with respect to the 2008 ozone, 2008 lead, and 2010 NO2 NAAQS with respect to section (110)(a)(1) and the following elements of section (110)(a)(2): (A), (C) with respect to minor NSR and PSD requirements, (D)(i)(II) elements 3 and 4, (D)(ii), (E), (F), (G), (H), (J), (K), (L), and (M); (B) for the 2008 Pb and 2008 ozone NAAQS and conditional approval of (B) for the 2010 NO2 NAAQS; and D(i)(I) elements 1 and 2 for the 2008 Pb and 2010 NO2 NAAQS.

(d) The Colorado Department of Public Health and Environment provided submissions to meet infrastructure requirements for the State of Colorado for the 2010 SO2 and 2012 PM2.5 NAAQS were received on July 10, 2013 and December 1, 2015, respectively. The State's Infrastructure SIP for the 2010 SO2 and 2012 PM2.5 NAAQS is approved with respect to section (110)(a)(1) and the following elements of section (110)(a)(2): (A), (B), (C) with respect to minor NSR and PSD requirements, (D)(i)(II), (D)(ii), (E), (F), (G), (H), (J), (K), (L), and (M).

(e) The Colorado Department of Environmental Quality submitted certification of Colorado's infrastructure SIP for the 2015 O3 NAAQS on September 17, 2018. Colorado's infrastructure certification demonstrates how the State, where applicable, has plans in place that meet the requirements of section 110 for the 2015 O3 NAAQS. The State's Infrastructure SIP for 2015 O3 NAAQS is approved with respect to CAA section 110(a)(1) and (2).

[77 FR 21452, Apr. 10, 2012, as amended at 78 FR 58188, Sept. 23, 2013; 80 FR 50206, Aug. 19, 2015; 82 FR 39031, Aug. 17, 2017; 85 FR 20178, Apr. 10, 2020]