EPA Approves Colorado's Smog-Fighting 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. These changes kick in on May 11, 2026, helping keep the air cleaner and healthier without extra costs for most businesses. Some parts still need fixing, but overall, Colorado’s on track to meet air quality goals.
Analyzed Economic Effects
3 provisions identified: 1 benefits, 0 costs, 2 mixed.
Cleaner air for Denver Metro area
The EPA approved Colorado's contingency measures for the Denver Metro/North Front Range (DMNFR) Serious ozone area, including a motor vehicle coating contingency measure. These approvals become federally effective on May 11, 2026 and are intended to help keep the air in the DMNFR area cleaner and healthier.
Emissions rules become federally enforceable
The EPA incorporated Colorado Regulations 7, 25, and 26 (as listed in Table 1) into the State Implementation Plan, making the adopted RACT requirements for landfill/biogas fired engines, refinery fuel process heaters (except heater H-1717), a cold rolling mill, and surface coating contingency measures federally enforceable as of May 11, 2026. The EPA did not finalize action for one process heater (H-1717) because of an identified error in Colorado's submitted regulatory language.
Prior EPA sanctions mostly lifted; one pending
Because the EPA is approving the relevant SIP revisions, the sanctions associated with the EPA's November 7, 2023 action are fully relieved and the EPA's December 8, 2023 disapproval is resolved for landfill/biogas engines and the cold rolling mill. However, EPA is not finalizing approval for the process heater H-1717 (identified error), so the RACT disapproval and associated sanctions regarding that heater are not yet fully resolved and remain deferred pending a corrected submission.
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Key Dates
Department and Agencies
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