## Facts

- Arkansas, Louisiana, Oklahoma, and Texas entered the congressionally approved Red River Compact allocating surface water in the Red River basin.
- The dispute concerned Reach II, subbasin 5, where the Compact gives the States “equal rights” to certain runoff and undesignated upstream inflows when flows exceed 3,000 CFS, subject to a 25% per-State cap on the excess.
- The Compact also preserves each State’s authority to use and control water within its boundaries so long as consistent with Compact obligations.
- Tarrant Regional Water District, a Texas water-supply agency, sought to obtain water for Texas customers by diverting water from sources located in Oklahoma within Reach II, subbasin 5.
- Tarrant applied to the Oklahoma Water Resources Board for permits to divert water from within Oklahoma for use in Texas.
- Oklahoma statutes, as applied by the State, restricted or effectively barred out-of-state entities from exporting Oklahoma water.
- Tarrant sued Oklahoma officials seeking declaratory and injunctive relief, arguing the Compact preempted Oklahoma’s export restrictions and that the restrictions violated the Dormant Commerce Clause.

## Issues

1. Whether the Red River Compact grants signatory States cross-border rights to divert water located within another signatory State, thereby preempting Oklahoma’s export-restriction statutes.
2. Whether Oklahoma’s water-export restrictions violate the Dormant Commerce Clause as discriminatory regulation of interstate commerce in water.

## Decision

- The Supreme Court unanimously affirmed judgment for Oklahoma officials.
- The Court held the Compact does not grant cross-border diversion rights; therefore Oklahoma’s export restrictions were not preempted.
- The Court held there was no Dormant Commerce Clause violation because the Compact’s federal allocation scheme left no unallocated water in the relevant area for the state statutes to burden as interstate commerce.

## Legal Principles

- Congressionally approved interstate compacts are construed as contracts; interpretation begins with text and structure, and ambiguity may be informed by history and course of performance.
- A State’s surrender of sovereign authority will not be inferred; it requires clear and unmistakable language, particularly when the claimed surrender would allow another State to exercise authority within its territory.
- Compact language allocating “equal rights” among States can apportion a shared resource without authorizing physical access across state lines, especially where the compact preserves each State’s intrastate control consistent with compact obligations.
- Federal preemption requires a conflict between state law and federal law; absent a compact-created right to cross-border diversion, state permitting and export restrictions may operate within the State’s boundaries.
- When Congress approves a compact that allocates a resource among States, the federal allocation can foreclose Dormant Commerce Clause challenges premised on discrimination as to water governed by that allocation.

## Conclusion

The Court read the Red River Compact to apportion water among the signatory States while preserving state-territorial control absent explicit cross-border diversion authority, leaving Oklahoma free to apply its water-export restrictions and defeating both preemption and Dormant Commerce Clause claims.


Tarrant Reg'l Water Dist. v. Herrmann, 569 U.S. 614 (2013)