Proposed rule · 2025-13342

Air Plan Partial Approval and Partial Disapproval; Colorado; Regional Haze Plan for the Second Implementation Period

The Environmental Protection Agency (EPA) is proposing to partially approve and partially disapprove a regional haze state implementation plan (SIP) submission submitted by the State of Colorado under the Clean Air Act (CAA) and the EPA's Regional Haze Rule (RHR) for the program's second implementation period. Colorado's 2022 SIP submission addresses the requirement that states revise their long-term strategies every implementation period to make reasonable progress towards the national goal of preventing any future, and remedying any existing, anthropogenic impairment of visibility, including regional haze, in mandatory Class I Federal areas. We propose to base our partial disapproval of Colorado's long-term strategy on its inclusion of insufficiently justified enforceable source closures that are not consistent with statutory requirements. Colorado's 2022 SIP submission also addresses other applicable requirements for the second implementation period of the regional haze program. Concurrently, the EPA is proposing to approve a revision to Colorado's SIP consolidating existing regional haze provisions into the same regulation where the State's new, second planning period provisions are located.