EPA repeals 2024 mercury and toxic emissions updates for coal plants, highlighting Louisville’s Mill Creek facility
Federal rollback centers on Mercury and Air Toxics Standards revisions
The U.S. Environmental Protection Agency on Feb. 20, 2026 finalized a repeal of amendments adopted in 2024 to the federal Mercury and Air Toxics Standards (MATS) for coal- and oil-fired electric generating units. The announcement was made during an event in Kentucky that referenced Louisville’s Mill Creek power plant, a major coal-fired facility serving the region.
The action does not eliminate MATS altogether. Instead, it removes the 2024 updates and returns compliance obligations to the baseline national standards originally finalized in 2012, which regulate hazardous air pollutants including mercury, acid gases and certain toxic metals emitted by power plants.
What the repeal changes and what remains in place
MATS sets limits on hazardous air pollutants from coal- and oil-fired power plants under the Clean Air Act framework for toxic emissions. EPA’s Feb. 2026 final action targets specific elements added in 2024, including revised requirements related to filterable particulate matter, an updated mercury standard for lignite-fired units, and requirements tied to continuous monitoring for particulate matter.
EPA characterized the pre-2024 framework as protective of public health, while describing the 2024 amendments as imposing additional compliance burdens. Environmental law groups and public-health advocates criticized the repeal, arguing it would weaken protections against mercury and other hazardous pollutants and reduce transparency tools designed to track emissions.
Louisville context: Mill Creek’s role in the regional power system
Mill Creek Generating Station, located in southwest Jefferson County along the Ohio River, is the largest coal-fired power plant operated by Louisville Gas & Electric. The facility consists of four coal-fired units that entered service between 1972 and 1982 and has been a central part of the area’s electricity supply for decades.
As a coal-fired unit subject to national air standards, Mill Creek’s compliance obligations are governed by the federal framework for hazardous air pollutants as well as other applicable state and federal requirements. Changes to federal standards can influence monitoring approaches and the compliance pathways utilities select, although the facility remains subject to the underlying 2012 MATS requirements following the repeal of the 2024 amendments.
Timeline of key milestones
2012: Federal MATS finalized, establishing nationwide limits for hazardous air pollutants from coal- and oil-fired power plants.
May 7, 2024: EPA finalized amendments updating parts of the MATS program.
June 17, 2025: EPA proposed repealing certain 2024 amendments and opened a public comment process.
Feb. 19–20, 2026: EPA finalized the repeal and announced the action in Kentucky while referencing Louisville’s Mill Creek plant.
The regulatory outcome preserves the original nationwide hazardous air pollutant limits for power plants while removing the most recent round of updates adopted in 2024.
What to watch next
The repeal is expected to draw continued scrutiny from states, utilities, public-health researchers and environmental litigators. The practical effects will depend on implementation details, any subsequent federal or court actions, and how individual power-plant operators adjust compliance strategies under the restored pre-2024 requirements.