A bipartisan group of U.S. senators are urging the Environmental Protection Agency (EPA) to withdraw a proposed rule that they said could “lead to the undoing” of the Obama administration’s Mercury and Air Toxics Standards (MATS). 

In a March 18 letter to newly appointed EPA administrator Andrew Wheeler, the group led by Sens. Lamar Alexander (R-Tenn.) and Tom Carper (D-Del.) asked that the agency withdraw its December 2018 proposed rule that finds it is no longer “appropriate and necessary” to regulate mercury and air toxic emissions from coal and oil power plants. 

Alexander and Carper were joined by Sens. Susan Collins (R-Maine), Joe Manchin (D-W.Va.), Thom Tillis (R-N.C.), and Sherrod Brown (D-Ohio). The lawmakers’ letter was made public the same day the EPA held a public hearing on the proposed rule in Washington D.C. 

In its proposed rule, the EPA refrained from removing coal- and oil-fired power plants from the list of source categories regulated under that section of the Clean Air Act, which means the EPA intends for the 2012-finalized MATS to remain in place. Crucially, however, the proposal outlined a revision in the agency’s final supplemental cost finding for MATS, which was required by a U.S. Supreme Court decision in June 2015, concluding it is not “appropriate and necessary” to regulate hazardous air pollutant emissions from power plants under the CAA’s Section 112. 

In their letter, the senators said they agree with the EPA’s decision to keep MATS in place. “However, if EPA finds that it is no longer ‘appropriate and necessary’ to regulate mercury emissions from coal and oil fired power plants, it could lead to the undoing, or weakening, of the Mercury Rule. This could result in installed mercury and air toxic control technology to be turned off, erasing all the benefits we have seen from the Mercury Rule,” they wrote. 

The senators’ position aligns with major trade groups, like the Edison Electric Institute, which claim owners and operators of coal and oil units have invested more than $18 billion to comply with the rule since it became effective in 2012. In their letter, the senators noted the last compliance deadline for MATS “passed more than two years ago and the utility industry has repeatedly stated that they support the Mercury Rule and that no changes are necessary.” 

The group added: “Mercury is a deadly toxin that harms the development of fetuses and children. It makes no sense to take any action that could lead to the weakening of mercury emission standards.” 

Among Republican senators urging EPA action to withdraw the proposed rule is Sen. Alexander, who has served in the Senate since 2003 and is not running for re-election in 2020. In a meeting on January 28 leading up to Wheeler’s confirmation hearing, Alexander told Wheeler that he would “not support any efforts that might jeopardize” MATS. Sens. Collins and Tillis will be on the ballot in 2020, and both will run in battleground states. Collins has been vocal about her opposition to EPA’s rollback of power plant rules, including for MATS and greenhouse gases. 

Manchin—a centrist Democrat from coal-rich West Virginia who now serves as the ranking member of the Senate Energy and Natural Resources Committee—voted against Wheeler’s confirmation, noting that changes to MATS are “inappropriate and will only serve to further undermine the status of our coal based utilities.” Carper serves as ranking member of the Environment and Public Works Committee. Tillis has been vocal about supporting the solar energy market, and he has opposed the Trump administration’s tariffs, which he says are hurting investment in solar projects in the state. 

On March 18, 30 health, business, environmental, and social justice groups also submitted a letter to the EPA urging the agency to withdraw the rule. “There is no defensible reason to continue to pursue this proposal to upend one of the most cost-effective and widely supported public health protections and we urge you to immediately withdraw it,” they wrote.

—Sonal Patel is a POWER associate editor (@sonalcpatel, @POWERmagazine).