## Facts

- Multiple comprehensive stream-system water-rights adjudications were initiated in Arizona state courts by the State and other water users; the United States was joined both on its own behalf and as trustee for several tribes.
- Several tribes, including the San Carlos Apache Tribe, filed parallel federal actions seeking determinations of their reserved water rights while the state proceedings were pending.
- In Montana, the United States and tribes first filed federal actions seeking adjudication of rights in certain streams; the State later initiated state-court adjudications covering the same waters and additional streams.
- Federal district courts dismissed or stayed the federal actions in both Arizona and Montana, relying on the McCarran Amendment and the approach taken in Colorado River.
- The Ninth Circuit reversed in both sets of cases, questioning Montana’s state-court jurisdiction and concluding that the federal actions should proceed notwithstanding the state adjudications.
- The Supreme Court consolidated review of the Arizona and Montana appeals.

## Issues

1. Whether state courts conducting comprehensive general stream adjudications have jurisdiction to determine federal and tribal reserved water rights, including rights held in trust by the United States.
2. Whether federal courts should dismiss or stay parallel federal suits brought by tribes and/or the United States in favor of ongoing, comprehensive state water adjudications.
3. Whether Montana’s enabling act and constitutional disclaimer provisions barred Montana courts from adjudicating Indian water rights in such proceedings.

## Decision

- The Supreme Court reversed the Ninth Circuit.
- The Court held that the McCarran Amendment permits and reflects congressional approval of state-court adjudication of federal and tribal water rights as part of comprehensive stream adjudications.
- The Court rejected the argument that Montana’s enabling act and constitutional disclaimer deprived Montana courts of authority to adjudicate Indian water rights in McCarran-type proceedings, in light of subsequent congressional actions (including Public Law 280).
- The Court held that, when a state general stream adjudication is comprehensive and the state court has jurisdiction, federal district courts should generally dismiss or stay parallel federal suits to avoid fragmented litigation and to respect the policy of unified adjudication.

## Legal Principles

- The McCarran Amendment waives federal sovereign immunity and supports state-court jurisdiction to adjudicate federal water rights, including tribal reserved rights held in trust by the United States, within comprehensive stream adjudications.
- Federal-law issues implicated by Indian reserved water rights do not create exclusive federal jurisdiction; state courts may apply federal law, with federal review available through appellate channels.
- Under the Colorado River doctrine, “wise judicial administration” can justify dismissal or stay of federal actions in favor of concurrent, comprehensive state water adjudications, provided the state forum has jurisdiction and is capable of resolving the claims.
- Deference to state proceedings is improper if the state court lacks jurisdiction over the claims at issue; it may also be inappropriate if the state proceeding is not actually moving forward such that no effective forum exists.

## Conclusion

The Court required deference to comprehensive state general stream adjudications that include federal and tribal water claims, holding that the McCarran Amendment authorizes state-court adjudication of Indian reserved water rights and that federal courts should ordinarily stay or dismiss parallel federal litigation when the state forum has jurisdiction and is proceeding.


Arizona v. San Carlos Apache Tribe, 463 U.S. 545 (1983)