In looking over recent developments, I realized that we have never addressed Acting Assistant Administrator Anne Idsal's November 26, 2019 guidance entitled “Interpreting ‘Adjacent’ for New Source Review and Title V Source Determinations in All Industries Other than Oil and Gas” (hereinafter Adjacency Policy), in which EPA states that it will “apply the Agency’s original interpretation expressed in the 1980 development of the Prevention of Significant Deterioration (PSD) portion of the NSR program, where we focused exclusively on proximity when considering whether properties are adjacent.” In so doing, the EPA rejected its prior practice of looking at physical proximity and functional relationship or interrelatedness in determining adjacency. The EPA encourages, but does not require, EPA-approved NSR programs to use this definition and reiterates that “source determinations are made by permitting authorities on a case-by-case basis after consideration of the relevant administrative record.” Adjacency Policy, at 1-2.
