## Facts

- The Coeur d’Alene Tribe originally lived on about three million acres in what is now northern Idaho, including Lake Coeur d’Alene and the St. Joe River, and relied on these waters for food, travel, and recreation.
- During westward expansion, the United States set aside a reservation for the Tribe in exchange for the Tribe’s cession of most of its aboriginal lands.
- In 1873, President Grant issued an executive order establishing reservation boundaries, but Congress did not immediately ratify it due to increasing non-Indian interest in parts of the area.
- The Tribe later ceded the northern two-thirds of Lake Coeur d’Alene while retaining the lower third of the lake and the St. Joe River area; Congress ratified the reservation boundaries in 1891.
- More than a century later, Idaho conducted the Coeur d’Alene–Spokane River Basin Adjudication (CSRBA), a general stream adjudication in state court.
- Acting as trustee, the United States filed 353 claims seeking recognition of federal reserved water rights to satisfy the purposes of the reservation; the Tribe joined the litigation.
- The CSRBA court bifurcated the matter into an entitlement phase (existence and scope of reserved rights) and a later quantification phase (amount of water).
- The Tribe presented evidence, including from a fisheries witness, that certain fish the Tribe used could migrate long distances (up to roughly 100 miles) to spawn, and that habitat conditions outside the reservation could affect on-reservation fisheries.
- The district court recognized reserved rights for agricultural use, domestic use, and for hunting and fishing; it also allowed reserved instream flow rights within the reservation, including in waterways crossing lands inside the reservation that were not owned by the Tribe or its members.
- The district court rejected claims for reserved instream flows outside reservation boundaries and rejected a theory framed as necessary to maintain the level of Lake Coeur d’Alene.
- On priority, the district court generally assigned the reservation-creation date for consumptive uses and “time immemorial” for nonconsumptive uses, but treated lands that had been patented to non-Indians and later reacquired by the Tribe differently—tying priority to a perfected state-law right, or if none existed (or it was lost), to the date of reacquisition.
- Idaho appealed the recognition of instream flows within the reservation on nontribal lands, and the United States and Tribe appealed the denial of off-reservation instream flows and related rulings; the appeals were consolidated in the Idaho Supreme Court.

## Issues

1. Whether the district court erred by applying the *United States v. New Mexico* “primary/secondary purposes” test, rather than evaluating the reservation as a tribal homeland when identifying purposes that support federal reserved water rights.
2. Whether, under a homeland-purpose analysis, the reservation’s purposes include aboriginal uses such as plant gathering and cultural uses in addition to hunting and fishing.
3. Whether the district court correctly denied federal reserved water rights for instream flows outside the reservation and for maintaining Lake Coeur d’Alene’s level.
4. Whether nonconsumptive reserved rights on lands that left tribal ownership and were later reacquired are entitled to a “time immemorial” priority date rather than a state-law priority date or the date of reacquisition.

## Decision

- The Idaho Supreme Court affirmed in part, reversed in part, and remanded.
- The Court held the district court improperly relied on *New Mexico*’s primary/secondary-purpose distinction and directed that entitlement be analyzed based on what water is needed for the reservation to function as a tribal homeland.
- Applying the homeland-purpose approach, the Court held the district court should have recognized additional aboriginal purposes—specifically plant gathering and cultural uses—when determining entitlement.
- The Court held the district court erred in assigning nonconsumptive reserved rights on reacquired lands a priority tied to state-law rights or reacquisition; those nonconsumptive rights carry a “time immemorial” priority.
- The Court otherwise affirmed the district court’s entitlement rulings, including recognition of instream flow rights within the reservation and the denial of instream flow rights outside the reservation and the denial of a reserved right to maintain the lake level.
- The case was remanded for further proceedings consistent with the homeland-purpose analysis and the corrected priority-date ruling.

## Legal Principles

- For Indian reservations, reserved water rights are determined by the purposes for which the reservation was set aside; for many reservations, those purposes are evaluated as providing a permanent tribal homeland rather than being limited by a primary/secondary-purpose split.
- Under a homeland-purpose analysis, reserved-rights purposes can include aboriginal subsistence and cultural practices (including plant gathering and cultural uses), not only agriculture or other consumptive uses.
- Federal reserved water rights may include instream flows within reservation boundaries when needed to meet reservation purposes.
- Reserved rights generally do not extend to instream flows outside reservation boundaries absent a valid legal basis; denial of off-reservation instream flow claims and lake-level maintenance claims may be upheld where such a basis is not shown.
- Nonconsumptive reserved water rights tied to aboriginal uses may have a “time immemorial” priority date, including on lands within the reservation that were alienated and later reacquired by the Tribe.

## Conclusion

In *In re CSRBA (Case No. 49576)*, the Idaho Supreme Court largely upheld the CSRBA court’s recognition of the Coeur d’Alene Tribe’s reserved rights for domestic, agricultural, and hunting-and-fishing purposes and instream flows within the reservation, and it affirmed the denial of off-reservation instream flows and lake-level maintenance claims; however, it reversed because the district court used the *New Mexico* primary/secondary-purpose test instead of analyzing the reservation as a tribal homeland (requiring recognition of aboriginal plant-gathering and cultural uses) and because it failed to give “time immemorial” priority to nonconsumptive reserved rights on reacquired lands, and it remanded for further proceedings.


In re CSRBA (Case No. 49576), United States of America and Coeur d'Alene Tribe, 448 P.3d 322 (2019)