Last week, EPA issued guidance to its Regional Administrators that addresses some of the questions raised by the decision in Utility Air Regulatory Group  v. United States Environmental Protection Agency, 134 S.Ct. 2427 (U.S. June 23, 2014) (“UARG”).   As discussed in our post of June 23rd, that decision raised several issues that must be clarified, including how to treat requirements in states that have adopted the Tailoring Rule approach and how to apply the prevention of significant deterioration (“PSD”) permitting provisions to modifications of major sources of emissions. 

For example, several states have adopted EPA’s Tailoring Rule approach into their state implementation plans (“SIPS’) and EPA has approved many of those SIP provisions.  Although EPA notes that it will no longer apply or enforce federal provisions, including EPA approved SIP provisions, that require a source to obtain permits if GHGs are the only pollutant involved.  Many state level requirements, however, remain in effect until further actions are taken and may trigger permitting requirements under state law despite the UARG decision.