(a) The requirements of sections 160 through 165 of the Clean Air Act are met, except for sources seeking permits to locate on Indian lands in the state of Iowa; and certain sources affected by the stack height rules described in a letter from Iowa dated April 22, 1987.

(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 Iowa for sources wishing to locate on Indian lands; and certain sources as identified in Iowa's April 22, 1987, letter.