US SUPREME COURT DECISIONS

The Elk Creek Dam is part of a three-dam project designed to control the water supply in Oregon's Rogue River Basin. The Army Corps of Engineers (Corps) completed an Environmental Impact Statement (EIS) for the Elk Creek project in 1971, and, in 1980, released its final Environmental Impact Statement, Supplement No. 1 (FEISS). Since the Rogue River is a premier fishing ground, the FEISS paid special heed to water quality, fish production, and angling, and predicted that the Elk Creek Dam would have no major effect on fish production, but that the effect of the Lost Creek and Elk Creek Dams on turbidity might, on occasion, impair fishing. After reviewing the FEISS, the Corps' Division Engineer decided to proceed with the project and, in 1985, Congress appropriated funds for construction of the dam, now one-third completed. Respondents, four Oregon nonprofit corporations, filed an action in the District Court to enjoin construction of the Elk Creek Dam, claiming that the Corps had violated the National Environmental Policy Act of 1969 (NEPA) by failing, among other things, to describe adequately the environmental consequences of the project; to include a "worst case analysis"; and to prepare a second supplemental EIS to review information in two documents developed after 1980. The first -- the Cramer Memorandum -- is an internal memorandum, prepared by two Oregon Department of Fish and Wildlife (ODFW) biologists based on a draft ODFW study on the effects of the Lost Creek Dam, suggesting that the Elk Creek Dam will adversely affect downstream fishing; and the second is a United States Soil Conservation Service (SCS) soil survey containing information that might be taken to indicate greater downstream turbidity than did the FEISS. The District Court denied relief on all claims and held, inter alia, that the Corps' decision not to prepare a second supplemental EIS to address the new information was reasonable. The Court of Appeals reversed, holding, among other things, that the FEISS was defective because it did not include a complete mitigation plan and "worst case analysis," and, with regard to the failure to prepare a supplemental EIS, that the ODFW and SCS documents brought to light significant new information chanrobles.com-red

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that was probably accurate, and that the Corps' experts failed to evaluate with sufficient care.

Held:

1. The Court of Appeals' conclusions that the FEISS was defective because it did not include a complete mitigation plan and a "worst case analysis" are erroneous for the reasons stated in Robertson v. Methow Valley Citizens Council, ante p. 490 U. S. 332. Pp. 490 U. S. 369-370.

2. The Corps' decision that the FEISS need not be supplemented is not arbitrary and capricious, and should not be set aside. Pp. 490 U. S. 370-385.

(a) An agency must apply a "rule of reason" and prepare a supplemental EIS if there remains "major Federal actio[n]" to occur, and if the new information will affect the quality of the human environment in a significant manner or to a significant extent not already considered. Although not expressly addressed in NEPA, such a duty is supported by NEPA's approach to environmental protection and its manifest concern with preventing uninformed action, as well as by Council on Environmental Quality and Corps regulations, both of which make plain that, at times, supplementation is required. Pp. 490 U. S. 370-374.

(b) Court review of the Corps' decision is controlled by the "arbitrary and capricious" standard of the Administrative Procedure Act, 5 U.S.C. § 706(2)(a). Respondents' supposition that the determination that new information is "significant" is either a question of law or of ultimate fact and, thus, "deserves no deference" on review is incorrect, since the resolution of this dispute involves primarily issues of fact concerning contentions that the new information is accurate and undermines the FEISS' conclusions, and that the Corps' review was incomplete, inconclusive, or inaccurate. Because analysis of the documents requires a high degree of technical expertise, this Court must defer to the informed discretion of the responsible agency. However, courts should not defer to an agency without carefully reviewing the record and satisfying themselves that the agency has made a reasoned decision based on its evaluation of the new information. Pp. 490 U. S. 375-378.

(c) The Corps conducted a reasoned evaluation of the relevant information in a formal Supplemental Information Report (SIR) and reached a decision that was not arbitrary and capricious. The Corps carefully scrutinized the Cramer Memorandum -- which did not reflect the neutral stand of ODFW's official position -- and, in disputing its accuracy and significance, hired two independent experts who found significant fault in the methodology and conclusions of the underlying draft ODFW study. Although the SIR did not expressly comment on the SCS survey, in light of in-depth studies conducted in 1974 and 1979, its chanrobles.com-red

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conclusion that "turbidity effects are not expected to differ from those described in the 1980 EISS" provided a legitimate reason for not preparing a supplemental FEISS to discuss turbidity. Pp. 490 U. S. 378-385.

832 F.2d 1489, reversed and remanded.

STEVENS, J., delivered the opinion for a unanimous Court. chanrobles.com-red

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