## Facts

- Congress ratified an 1888 agreement setting apart the Fort Belknap Indian Reservation as a permanent home for the Gros Ventre and Assiniboine tribes.
- The Milk River, a non-navigable stream, formed the reservation’s northern boundary; the region was arid and farming required irrigation.
- The tribes and the United States maintained livestock and sought to support agriculture on reservation lands bordering the Milk River.
- After the reservation was created and after Montana achieved statehood, non-Indian settlers upstream acquired lands and diverted Milk River water through dams and reservoirs under state prior-appropriation principles.
- The diversions reduced water reaching the reservation, threatening irrigation and the reservation’s intended agricultural use.
- The United States sued to enjoin upstream diversions, asserting that sufficient water was reserved by implication when the reservation was established, even though the 1888 agreement did not expressly mention water rights.
- A federal court issued an interlocutory injunction protecting a specified amount of water for reservation use and later entered a permanent injunction; the Ninth Circuit affirmed.
- Some defendants defaulted and did not appeal; Winters and others appealed to the Supreme Court, raising both appellate-jurisdiction and merits issues.

## Issues

1. Whether the Supreme Court had jurisdiction to hear an appeal when only some of multiple defendants appealed from an injunction decree.
2. Whether the 1888 reservation agreement impliedly reserved sufficient Milk River water for reservation purposes, limiting later upstream appropriations under state law.

## Decision

- The Supreme Court affirmed the decree.
- The Court held it had jurisdiction because the decree operated against defendants as separate wrongdoers; non-appealing or defaulting defendants did not bar the appeal by others.
- On the merits, the Court held that establishing the reservation impliedly reserved enough Milk River water to fulfill the reservation’s purposes, including irrigation, and later state-law appropriations could not diminish that federal right.
- The Court rejected the claim that Montana’s statehood displaced or subordinated the federally reserved right.

## Legal Principles

- When the United States sets aside land for an Indian reservation, it impliedly reserves sufficient water to accomplish the reservation’s purposes, even absent express water-rights language.
- Federally reserved water rights are not defeated by later state-law prior appropriations and are protected against upstream diversions that would impair the reserved use.
- Federal power may reserve and exempt territorial waters from later state appropriation regimes after statehood.
- In construing agreements with Indians, ambiguous terms and implications are read from the standpoint of the Indians and in favor of the interpretation that best fits the reservation’s intended use.
- The joinder requirement for appeals applies to truly joint decrees; where defendants are separately responsible, some may appeal without others.

## Conclusion

The Court upheld an injunction protecting water necessary for the Fort Belknap Reservation, recognizing that the reservation’s creation carried an implied, federally protected right to sufficient Milk River water for its intended agricultural and related uses, senior to later upstream diversions under state law.


Winters v. United States, 207 U.S. 564 (1908)