The 10th United States Court of Appeals upheld Wyoming’s plan for controlling emissions of sulfur dioxide (SO2) under the Clean Air Act’s regional haze program.  Environmental groups, including the Sierra Club and WildEarth Guardians, challenged the EPA’s approval of Wyoming’s plan on the ground that the plan failed to guarantee progress toward the goal of natural visibility conditions in national parks and wilderness areas.

In a unanimous three-judge opinion, the Court of Appeals agreed with Wyoming and the EPA that Wyoming’s plan fulfills the requirements of the regional haze program. The Court found that many of the environmental groups’ arguments were wrong as a matter of law and denied their remaining claims as untimely. The court instead adopted arguments Wyoming presented in defense of its plan. Governor Mead applauded the Court’s decision.

Still pending before the Tenth Circuit Court of Appeals is Wyoming’s challenge to the EPA’s partial disapproval of the State’s related plan for reducing emissions of haze-causing nitrogen dioxide (NOx). Last month, the Court granted Wyoming’s request to stay the EPA’s disapproval while the Court reviews Wyoming’s appeal.

This means Wyoming’s current plan to mitigate (NOx) will continue during the appeal. A final decision in the case likely will not come until late 2015 or early 2016.