## Facts

- The U.S. Army Corps of Engineers operated the Missouri River Mainstem Reservoir System under the Flood Control Act of 1944 and a governing Master Water Control Manual.
- A 2000 U.S. Fish and Wildlife Service biological opinion under ESA § 7 concluded the Corps’ then-proposed operations were likely to jeopardize three listed species and recommended flow changes to mimic natural seasonal variation.
- Drought and competing demands (navigation, flood control, hydropower, recreation, and species protection) produced extensive litigation and conflicting district court orders concerning reservoir releases.
- The Judicial Panel on Multidistrict Litigation consolidated related cases in the District of Minnesota.
- In 2004, the Corps issued a revised Master Manual and related operating plans, relying on updated ESA consultation that moved from mandatory flow modifications toward habitat-creation measures.
- Environmental groups, navigation interests, states, and tribal entities challenged the 2004 Master Manual and the revised biological opinion under the ESA, NEPA, the Flood Control Act, and the APA.
- The district court granted summary judgment for the Corps and Fish and Wildlife Service on all claims.

## Issues

1. Whether the Flood Control Act of 1944 required the Corps to prioritize downstream navigation (and flood control) over other authorized purposes when operating the system.
2. Whether the Corps and Fish and Wildlife Service violated the ESA by adopting and relying on the revised biological opinion concluding operations would avoid jeopardy through modified measures.
3. Whether the Corps’ adoption of the 2004 Master Manual and related plans violated NEPA or was arbitrary and capricious under the APA.

## Decision

- The Eighth Circuit affirmed summary judgment for the Corps and Fish and Wildlife Service.
- The Flood Control Act was held to authorize the Corps to balance multiple congressionally identified purposes; it did not impose an absolute priority for navigation.
- The revised biological opinion and the Corps’ reliance on it were upheld as reasonable under deferential APA review, including the agency’s explained change from flow-focused measures to habitat-based measures.
- NEPA and APA challenges were rejected because the agencies considered relevant factors, evaluated alternatives, and articulated a rational basis for the 2004 Master Manual and operating approach.

## Legal Principles

- When a statute authorizes multiple project purposes, an agency generally retains operational discretion to balance those purposes absent a clear statutory command imposing a rigid priority.
- ESA § 7 consultation determinations reflected in a biological opinion are reviewed under the APA; courts uphold the agency’s scientific judgments if the agency reasonably explains its conclusions and connects them to the administrative record.
- Under arbitrary-and-capricious review, courts set aside agency action only when the agency relied on improper factors, failed to consider an important aspect of the problem, or offered an explanation contrary to the record or otherwise irrational.
- NEPA requires a reasoned evaluation of environmental consequences and alternatives; it does not require selection of a particular alternative if the agency’s analysis and explanation are adequate.

## Conclusion

The court upheld the 2004 Missouri River operating framework, ruling that the Corps could balance competing authorized purposes and that the agencies’ ESA and NEPA processes and conclusions were adequately explained and not arbitrary or capricious under the APA.


In re Operation of the Missouri River System Litig., 421 F.3d 618 (8th Cir. 2005)