How the Wind Blows

In State of Texas v. EPA, the Fifth Circuit upheld the EPA’s authority to substantively evaluate and disapprove a State Implementation Plan under the Clean Air Act’s Good Neighbor Provision. The court confirmed that EPA may require SIPs to address both “significant[] contribut[ion] to nonattainment” and independent “interfere[nce] with maintenance” in other states, including areas not formally designated nonattainment, and emphasized that “The text puts EPA in the driver’s seat for evaluating a SIP’s compliance with the CAA.”

The court also approved EPA’s reliance on up-to-date interstate transport modeling and a 2017 projection year as reasonable, reiterating that “nothing in the statute places the EPA under an obligation to provide specific metrics to States before they undertake to fulfill their good neighbor obligations.” Because Texas’s SIP lacked analysis quantifying downwind impacts and ignored maintenance receptors, EPA’s disapproval was neither arbitrary nor capricious. 16-60670; Sept. 22, 2025. A dissent would vacate the EPA’s action for missing the 12-month deadline established by a statute.