MITCHELL, SD (Mitchell Now) — Environmental groups say they are weighing legal action after the U.S. Environmental Protection Agency finalized its repeal of the 2009 “Endangerment Finding,” a key determination that greenhouse gases pose a threat to public health and welfare and can be regulated under the Clean Air Act.

EPA Administrator Lee Zeldin and President Donald Trump announced the repeal Feb. 12, describing it as the “single largest deregulatory action in U.S. history,” and arguing it will reduce compliance costs for industry and consumers.

Environmental advocates and public-interest groups, including organizations that have previously defended climate regulations in court, say they are exploring litigation and other responses, contending the repeal undermines long-standing climate protections.

The Endangerment Finding has served as a central legal basis for federal rules aimed at reducing greenhouse gas pollution from vehicles and other sources. Analysts say the rollback could have sweeping implications for federal climate policy, though court challenges are expected to shape what happens next.

Susanne Skyrm, treasurer of the Sierra Club’s South Dakota chapter, said she is concerned about the potential impacts of weaker federal greenhouse gas oversight