## Facts

- The U.S. Army Corps of Engineers managed the Missouri River Mainstem Reservoir System under the Flood Control Act of 1944, which assigns multiple purposes in diminishing order of priority, including flood control, irrigation, navigation, power, domestic and sanitary uses, wildlife, and recreation.
- The Corps used a publicly available operating framework (the “Master Manual”) describing how it planned to balance these competing purposes while retaining operational flexibility.
- During drought conditions, the Corps implemented a preestablished approach to support downstream navigation by drawing releases primarily from one of six reservoirs on an annual rotating basis.
- For the 2002 navigation season, the Corps selected Lake Oahe (South Dakota) as the principal source of releases.
- South Dakota sued federal Corps officials, alleging the Lake Oahe decision was arbitrary and capricious and would cause irreparable harm to a planned fish-spawning operation, and obtained a preliminary injunction restricting the Corps’ planned releases.
- Downstream navigation interests and related commercial entities, as well as Nebraska, sought to intervene in the South Dakota action; the district court denied intervention.
- After operational adjustments prompted by the South Dakota injunction, Nebraska filed a separate action and obtained an injunction directing the Corps to proceed with the original 2002 operating plan to release water for navigation consistent with the Master Manual.
- North Dakota obtained injunctive relief in its own action concerning impacts on its reservoirs.
- The Corps appealed the preliminary injunctions; proposed intervenors appealed the denials of intervention. The Eighth Circuit consolidated the appeals.

## Issues

1. Whether, and to what extent, Corps reservoir-operation decisions under the Flood Control Act were judicially reviewable under the APA and federal-question jurisdiction, or instead committed to agency discretion.
2. Whether the preliminary injunctions entered in multiple districts improperly dictated system-wide reservoir operations and created conflicting obligations for the Corps.
3. Whether proposed intervenors (states and private navigation/commercial entities) were entitled to intervene as of right under Federal Rule of Civil Procedure 24(a)(2), or permissively, in the South Dakota action.

## Decision

- The Eighth Circuit reversed or vacated substantial portions of the preliminary injunctions that effectively compelled specific reservoir-operation outcomes and placed the Corps under inconsistent judicial commands.
- The court held that the district courts exceeded the permissible scope of preliminary equitable relief by substituting judicial direction for the Corps’ system-wide operational judgment in managing an interstate river system.
- The court treated the Master Manual as guidance rather than a rigid, judicially enforceable mandate requiring particular operational choices in changing hydrologic conditions.
- The court affirmed the denial of intervention as of right for various proposed intervenors in the South Dakota case, concluding that Rule 24(a)(2) requirements were not met, including inadequate representation by existing parties.

## Legal Principles

- Courts may review agency action for legal error, including arbitrary-and-capricious decision-making where applicable, but should not use preliminary injunctions to assume day-to-day operational control of complex, technical, multi-purpose federal water projects.
- Injunctive relief must be narrowly tailored and must account for the multi-state and system-wide consequences of orders affecting integrated reservoir operations, including the risk of conflicting injunctions.
- Planning and operational manuals that describe agency approaches to balancing statutory purposes do not necessarily eliminate agency discretion or convert flexible management tools into binding judicial commands.
- Intervention as of right under Rule 24(a)(2) requires a significantly protectable interest, practical impairment of that interest, and inadequate representation by existing parties; overlapping interests with federal defendants that are already defending the challenged operations generally defeat inadequate-representation showings.

## Conclusion

The Eighth Circuit limited the use of preliminary injunctions to direct Missouri River reservoir operations, emphasizing deference to the Corps’ system-wide technical management under the Flood Control Act and the need to avoid conflicting district-court control, while largely upholding denials of intervention as of right for navigation-related and other proposed intervenors.


South Dakota v. Ubbelohde, 330 F.3d 1014 (8th Cir. 2003)