40 CFR § 52.1387
Visibility protection
June 9, 2020
(a) The requirements of section 169A of the Clean Air Act are not met because the plan does not include approvable procedures for protection of visibility in mandatory Class I Federal areas.
(b) [Reserved]
(c) Montana's November 7, 2017 Progress Report meets the applicable regional haze requirements set forth in §51.308(g) and (h).
[52 FR 45138, Nov. 24, 1987, as amended at 82 FR 3129, Jan. 10 2017; 84 FR 53061, Oct. 4, 2019]