Wyoming v. EPA, et al., No. 14-9529 (10th Cir. 2023)
Annotate this CaseThis case involved Wyoming’s plan to regulate emissions from powerplants within its borders that produce pollutants that contribute to regional haze, reducing visibility in and the aesthetics to national parks and wilderness areas. Wyoming produced a state implementation plan (SIP) in 2011. In a 2014 final rule, the EPA approved the SIP in part (as to Naughton) and disapproved it in part (as to Wyodak). Through a federal implementation plan (FIP), the EPA also substituted its determination of the proper technology to install at Wyodak, replacing Wyoming’s SIP. Wyoming and PacifiCorp petitioned for review, arguing the SIP should be entirely approved and claiming the EPA failed to grant Wyoming the deference required by federal law when it disapproved the Wyodak portion. Several conservation groups also challenged the rule, arguing the Naughton 1 and 2 portion should have been disapproved because the EPA failed to require the best available technology to reduce regional haze in a timely manner. The Tenth Circuit Court of Appeals granted the petition as to Wyodak and vacated that portion of the final rule. The Court found the EPA erred in evaluating the Wyodak portion of the SIP because it treated non-binding agency guidelines as mandatory in violation of the Clean Air Act. The Court remanded that part of the final rule to the agency for further review. But because the EPA properly approved Wyoming’s determination of the best technology for Naughton, the Court denied the petition as to those units and upheld that portion of the final rule.
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