John Paul Stevens

“ The EPA took particular note of the two then-recent Court of Appeals decisions, which had created the bright-line rule that the “bubble concept” should be employed in a program designed to maintain air quality but not in one designed to enhance air quality. Relying heavily on those cases, [29] EPA adopted a dual definition of “source” for nonattainment areas that required a permit whenever a change in either the entire plant, or one of its components, would result in a significant increase in emissions even if the increase was completely offset by reductions elsewhere in the plant. ”

“ Policy The arguments over policy that are advanced in the parties' briefs create the impression that respondents are now waging in a judicial forum a specific policy battle which they ultimately lost in the agency and in the 32 jurisdictions opting for the “bubble concept,” but one which was never waged in the Congress. Such policy arguments are more properly addressed to legislators or administrators, not to judges. ”

“ Judges are not experts in the field, and are not part of either political branch of the Government. Courts must, in some cases, reconcile competing political interests, but not on the basis of the judges' personal policy preferences. In contrast, an agency to which Congress has delegated policy-making responsibilities may, within the limits of that delegation, properly rely upon the incumbent administration's views of wise policy to inform its judgments. ”

“ Significantly, the EPA expressly noted that the word “source” might be given a plantwide definition for some purposes and a narrower definition for other purposes. It wrote:
“Source means any building structure, facility, or installation which emits or may emit any regulated pollutant. ‘Building, structure, facility or installation’ means plant in PSD areas and in nonattainment areas except where the growth prohibitions would apply or where no adequate SIP exists or is being carried out.” ”

“ The term ‘lowest achievable emission rate’ means for any source, that rate of emissions which reflects-“ (A) the most stringent emission limitation which is contained in the implementation plan of any State for such class or category of source, unless the owner or operator of the proposed source demonstrates that such limitations are not achievable, or“ (B) the most stringent emission limitation which is achieved in practice by such class or category of source, whichever is more stringent. ”

“ Use of only a plant-wide definition of source will permit plant-wide offsets for avoiding NSR of new or modified pieces of equipment. However, this is only appropriate once a SIP is adopted that will assure the reductions in existing emissions necessary for attainment. See 44 FR 3276 col. 3 (January 16, 1979) . If the level of emissions allowed in the SIP is low enough to assure reasonable further progress and attainment, new construction or modifications with enough offset credit to prevent an emission increase should not jeopardize attainment. ”

“ Respondents argue if an old plant containing several large emitting units is to be modernized by the replacement of one or more units emitting over 100 tons of pollutant with a new unit emitting less-but still more than 100 tons-the result should be no different simply because “it happens to be built not at a new site, but within a pre-existing plant.” ”

“ We hold that the EPA's definition of the term “source” is a permissible construction of the statute which seeks to accommodate progress in reducing air pollution with economic growth. “The Regulations which the Administrator has adopted provide what the agency could allowably view as ... [an] effective reconciliation of these twofold ends....” United States v. Shimer, 367 U.S., at 383, 81 S.Ct., at 1560.
The judgment of the Court of Appeals is reversed. ”

“ The term ‘reasonable further progress' means annual incremental reductions in emissions of the applicable air pollutant (including substantial reductions in the early years following approval or promulgation of plan provisions under this part and section 110 (a) (2) (I) and regular reductions thereafter) which are sufficient in the judgment of the Administrator, to provide for attainment of the applicable national ambient air quality standard by the date required in section 172 (a) . ”

“ New Source Performance Standards (NSPS) will continue to apply to many new or modified facilities and will assure use of the most up-to-date pollution control techniques regardless of the applicability of nonattainment area new source review.“7. In order to avoid nonattainment area new source review, a major plant undergoing modification must show that it will not experience a significant net increase in emissions. Where overall emissions increase significantly, review will continue to be required.” ”

“ In general, the Ruling provided that “a major new source may locate in an area with air quality worse than a national standard only if stringent conditions can be met.” Id., at 55525. The Ruling gave primary emphasis to the rapid attainment of the statute's environmental goals. [20] Consistent with that emphasis, the construction of every new source in nonattainment areas had to meet the “lowest achievable emission rate” under the current state of the art for that type of facility. See Ibid. The 1976 Ruling did not, however, explicitly adopt or reject the “bubble concept.” ”

“ By giving a plant manager flexibility to find the places and processes within a plant that control emissions most cheaply, pollution control can be achieved more quickly and cheaply.” L. Lave & G. Omenn, Cleaning Air: Reforming the Clean Air Act 28 (1981) (footnote omitted) .↑ Respondents point out if a brand new factory that will emit over 100 tons of pollutants is constructed in a nonattainment area, that plant must obtain a permit pursuant to § 172 (b) (6) and in order to do so, it must satisfy the § 173 conditions, including the LAER requirement. ”

“ It interpreted the policies of the statute, however, to mandate the plantwide definition in programs designed to maintain clean air and to forbid it in programs designed to improve air quality. Respondents place a fundamentally different construction on the statute. They contend that the text of the Act requires the EPA to use a dual definition-if either a component of a plant, or the plant as a whole, emits over 100 tons of pollutant, it is a major stationary source. ”

“ If, however, the court determines Congress has not directly addressed the precise question at issue, the court does not simply impose its own construction on the statute, [10] as would be necessary in the absence of an administrative interpretation. Rather, if the statute is silent or ambiguous with respect to the specific issue, the question for the court is whether the agency's answer is based on a permissible construction of the statute. [11]
“The power of an administrative agency to administer a congressionally created ... ”

“ The section has two main purposes: (1) to allow reasonable economic growth to continue in an area while making reasonable further progress to assure attainment of the standards by a fixed date; and (2) to allow [p852] States greater flexibility for the former purpose than EPA's present interpretative regulations afford.
“The new provision allows States with nonattainment areas to pursue one of two options. First, the State may proceed under EPA's present ‘tradeoff’ or ‘offset’ ruling. ”

“ On the other hand, the meaning of a word must be ascertained in the context of achieving particular objectives, and the words associated with it may indicate that the true meaning of the series is to convey a common idea. ”

“ Also, Congress intended under Section 173 of the Act that States would have some latitude to depart from the strict requirements of this Ruling when the State plan is revised and is being carried out in accordance with Part D. Under a Part D plan, therefore, there is less need to subject a modification of an existing facility to LAER and other stringent requirements if the modification is accompanied by sufficient intrasource offsets so that there is no net increase in emissions. ”

“ Different definitions of ‘source’ can therefore be used for different sections of the statute....“Moreover, Alabama Power and ASARCO taken together suggest that there is a distinction between Clean Air Act programs designed to enhance air quality and those designed only to maintain air quality......... ”