40 CFR § 52.343 - Significant deterioration of air quality.
(a) The requirements of sections 160 through 165 of the Clean Air Act are not met for the following categories of sources for preventing the significant deterioration of air quality:
(1) Sources locating on Indian lands.
(2) Sources locating on Indian Reservations.
(3) Sources which constructed prior to September 2, 1986 and which have not otherwise subjected themselves to Colorado's PSD permitting regulations after September 2, 1986, either through application to Colorado for a PSD permit (in the case of those sources which improperly constructed without obtaining a PSD permit) or through application to Colorado for a major modification to the source.
(b) Regulations for preventing significant deterioration of air quality. The provisions of § 52.21 except paragraph (a)(1) are hereby incorporated and made a part of the applicable State plan for the State of Colorado for the sources identified in paragraph (a) of this section as not meeting the requirements of sections 160-165 of the Clean Air Act.
(c) The State of Colorado has clarified the generalized language contained in the Colorado Air Quality Control Regulations on the use of “applicable air quality models.” In a letter to Douglas M. Skie, EPA, dated May 19, 1989, Bradley J. Beckham, Director of the Air Pollution Control Division stated:
* * * All PSD permits reviewed by the Division will use the revised modeling guideline mentioned above [Guideline on Air Quality Models (Revised), EPA 450/2-78-027R including Supplement A (July 1987)] for determining if the air quality models, data bases, and other requirements are generally approved by EPA. Any future revisions (including appendices or supplement) will be incorporated into the Division's protocol for reviewing modeling for PSD permits.