temporary emissions,” paired with its exclusion of “secondary emissions” and certain fugitive emissions from the potential-to-emit calculation, demonstrated that EPA did not intend to exclude all temporary emissions from the calculation. The Court noted that “[h]ad the EPA originally intended to exclude all temporary emissions under § 51.165, it would have said so.” Order at 15. The Court held that EPA acted contrary to law when it approved the SIP revision, and thus vacated EPA’s final rule approving the SIP revision “insofar as it allowed Colorado to exclude all temporary emissions under its NNSR permit program” and remanded to EPA for further proceedings.CBD also challenged Colorado’s exclusion of “emissions from internal combustion engines on any vehicle” from major source determination, but the Court found that such an exclusion was permitted under the CAA as nonroad engines are specifically excluded from the federal definition of a stationary source. See 42 U.S.C. §§ 7502(c)(5), 7602(z) (Defining a “stationary source” as “any source of an air pollutant except those emissions resulting directly from . . . a nonroad engine.”).Implications for the IndustryInclusion of temporary emissions in the potential-to-emit calculation is a substantial shift from the current regulation of air emissions in the Denver Metro North Front Range (DMNFR) area. There are now several potential impacts to the permitting of oil and gas facilities. For instance, under Colorado’s existing rules, air emissions from the construction and exploration of oil and gas production facilities have not included a facility’s potential to emit. As a result of the Tenth Circuit’s ruling, new or modified oil and gas facilities in the DMNFR area may be required to account for temporary sources of emissions unless those emissions can be classified as “secondary emissions,” under § 51.165, or originate from nonroad engines. Including temporary emissions may push some stationary sources over the threshold from a

Although the approach has not been widely used, it is supported by case law developed in connection with acid rain and its use is consistent with the legislative history of the 1977 Amendments to the Clean Air Act, where Congress added “climate” to the definition of “effects on welfare” due to concerns about global cooling caused by sulfur dioxide emissions. 42 U.S.C. § 7602(h). Third, it would be based on a science-based goal adopted under the UNFCCC, a treaty that has been ratified with the advice and consent of the Senate.

Utah Physicians,supra.In re Volkswagen “Clean Diesel” Marketing, Sales Practices, and Products Liability Litigation., 894 F.3d 1030, 1043 (9th Circuit 2018).Utah Physicians for a Healthy Environment v. Diesel Power Gear LLC, et al., 374 F. Supp.3d 1124, 1137 (D. Utah 2019). 42 U.S.C. § 7602(k).Utah Physicians, 374 F. Supp.3d at 1137-1138.

Prot. Agency, No. 16-9556, 2018 WL 3543036, at *1 (10th Cir. July 24, 2018) citing 42 U.S.C. § 7602(t). Colorado submitted an attainment plan to the EPA in 2002 to bring the Lamar area into attainment.

The Rosebush plant emits slightly less than 100 tons per year of sulfur dioxides (SO2) and nitrous oxides (NOx). Because the Rosebush plant's emissions are under the 100 tons per year threshold, the facility would not need to obtain a Title V operating permit unless the emissions from some or all of the wells were aggregated with the emissions from the plant.See 42 U.S.C. § 7602(j). EPA regulations allow aggregation of multiple pollutant-emitting activities such that they are considered a single stationary source only if all of the emission units (1) are under common control, (2) "are located on one or more contiguous or adjacent properties," and (3) belong to the same major industrial grouping (i.e., have the same SIC code).