John Paul Stevens

“ Yet, even if both documents had given rise to prompt expressions of concern, there are good reasons for concluding that they did not convey significant new information requiring supplementation of the FEISS.
The Court of Appeals attached special ignificance to two concerns discussed in the Cramer Memorandum: the danger that an increase in water temperature downstream during fall and early winter will cause an early emergence and thus reduce survival of spring chinook fry and the danger that the dam will cause high fish mortality from an epizootic disease. ”

“ Respondents contend that the determination of whether the new information suffices to establish a "significant" effect is either a question of law or, at a minimum, a question of ultimate fact and, as such, "deserves no deference" on review. Brief for Respondents 29. Apparently, respondents maintain that the question for review centers on the legal meaning of the term "significant" or, in the alternative, the predominantly legal question whether established and uncontested historical facts presented by the administrative record satisfy this standard. ”

“ In its chapter on the environmental effects of the proposed project, the FEISS explained that water quality studies were prepared in 1974 and in 1979 and that " [w] ater temperature and turbidity have received the most attention." FEISS 33. Using computer simulation models, the 1974 study predicted that the Elk Creek Dam might, at times, increase the temperature of the Rogue River by one to two degrees Fahrenheit and its turbidity by one to three JTU's. ”

“ In his decision, he identified the mitigation measures that had already been taken with respect to the loss of anadromous fish spawning habitat, as well as those that would "most likely" be taken to compensate for the loss of other wildlife habitat. ”

“ If there remains "major Federal actio [n] " to occur, and if the new information is sufficient to show that the remaining action will "affec [t] the quality of the human environment" in a significant manner or to a significant extent not already considered, a supplemental EIS must be prepared. [20] Cf. 42 U.S.C. § 4332 (2) (C) .
The parties disagree, however, on the standard that should be applied by a court that is asked to review the agency's decision. ”

“ This inquiry must "be searching and careful," but "the ultimate standard of review is a narrow one." Ibid. When specialists express conflicting views, an agency must have discretion to rely on the reasonable opinions of its own qualified experts even if, as an original matter, a court might find contrary views more persuasive. ”

“ The parties are in essential agreement concerning the standard that governs an agency's decision whether to prepare a supplemental EIS. They agree that an agency should apply a "rule of reason," and the cases they cite in support of this st ndard explicate this rule in the same basic terms. These cases make clear that an agency need not supplement an EIS every time new information comes to light after the EIS is finalized. ”

“ The Role of Executive Oversight in the Implementation of Environmental Policy, 64 Ind.L.J. 205, 247-248 (1989) (Supplementation is at times necessary because " [t] he entire efficacy of the EIS process is called into question when changes are made to a project after the publication of a final impact statement") .↑ In support of this latter proposition, we cited Environmental Defense Fund v. ”