EPA Approves Colorado's Smog Cleanup Plan for Denver Area
Published Date: 4/9/2026
Rule
Summary
The EPA is giving a thumbs-up to Colorado’s plan to clean up smog in the Denver Metro/North Front Range area by approving new rules for controlling pollution from vehicles and certain factories. Some parts, like controls on pneumatic devices and one refinery heater, need more work, but most changes kick in by May 11, 2026. This means cleaner air for locals without big new costs, thanks to smart, targeted fixes.
Analyzed Economic Effects
5 provisions identified: 1 benefits, 2 costs, 2 mixed.
Refinery Heater H-1717 RACT Pending Correction
The EPA did not finalize approval of the RACT determination for refinery process heater H-1717 because the State submitted an incorrect entry for that unit; EPA will act on a corrected submission in the future. The June 18, 2025 interim final determination remains in effect with sanctions deferred pending EPA action on the anticipated correction for H-1717.
Prior EPA Sanctions Fully Relieved
Because EPA is approving the portions of Colorado's SIP submittals identified in this final rule, the sanctions associated with EPA's November 7, 2023 action are now fully relieved for the approved elements as of May 11, 2026. However, sanctions related to the remaining unapproved portion for heater H-1717 are not yet fully resolved and remain subject to the June 18, 2025 interim final determination with sanctions deferred pending correction.
Motor Vehicle Coating Rule Approved
The EPA approved Colorado's motor vehicle coating contingency measure as part of the State Implementation Plan, and that approval becomes effective May 11, 2026. This means the regulatory text implementing the submitted automotive coating contingency measure is incorporated into the federally enforceable SIP as of that date.
RACT Rules Approved for Select Sources
The EPA approved Colorado's RACT (Reasonably Available Control Technology) regulatory revisions for landfill/biogas fired engines and a cold rolling mill, and approved most refinery fuel process heater RACT revisions, effective May 11, 2026. Those regulatory revisions are now incorporated into the federally enforceable SIP for the Denver Metro/North Front Range Serious ozone area.
Pneumatic Controller Contingency Not Acted On
The EPA is not taking action on one contingency measure in Colorado's submission that concerns pneumatic controllers. That specific contingency measure remains unapproved in this final rule (effective May 11, 2026) and is not incorporated into the SIP by this action.
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