Arizona v. Navajo Nation: The 2023 Ruling That Moved the Fight Over Colorado River Water From the Courthouse to Congress

The case name matters, and so does what the Court did not decide

The case is Arizona v. Navajo Nation, not Navajo Nation v. Arizona. That inversion is not pedantry. Arizona, Nevada, and Colorado intervened against the Tribe to protect their Colorado River interests; the United States was a petitioner in a companion case, Department of the Interior v. Navajo Nation. The caption tells you who had to defend a water supply and who had to defend a water right.

On June 22, 2023, the Supreme Court reversed the Ninth Circuit and held that the 1868 treaty establishing the Navajo Reservation reserved necessary water but did not require the United States to take affirmative steps to secure it. The vote was 5–4. Justice Kavanaugh wrote the majority, joined by Chief Justice Roberts and Justices Thomas, Alito, and Barrett. Justice Gorsuch dissented, joined by Justices Sotomayor, Kagan, and Jackson. Justice Thomas filed a separate concurrence questioning the constitutional underpinnings of the federal-tribal trust relationship.

The ruling did not extinguish Navajo water rights. It did something narrower and, for that reason, more consequential: it closed one litigation pathway and redirected the dispute into forums where the Navajo Nation has less procedural leverage and where the timeline is measured in congressional sessions and state-court dockets rather than in a single appeal.

What the Court actually held

The Navajo Nation sued the Department of the Interior, the Secretary of the Interior, the Bureau of Reclamation, and the Bureau of Indian Affairs, alleging that the United States had breached its trust obligations under the 1868 treaty by failing to assess the Tribe’s water needs, develop a plan to secure water, and potentially build pipelines, pumps, wells, or other infrastructure. The Tribe did not claim that the United States had interfered with its existing water access. It claimed the treaty compelled the federal government to act.

The Court disagreed. Writing for the majority, Justice Kavanaugh reasoned that to sustain a breach-of-trust claim, the Tribe had to identify specific rights-creating or duty-imposing language in a treaty, statute, or regulation. The 1868 treaty imposed several affirmative duties on the United States—building schools, a chapel, and other structures; providing teachers for at least ten years; supplying seeds and agricultural implements for up to three years; funding the purchase of sheep, goats, cattle, and corn. It said nothing about an affirmative duty to secure water. That silence, the Court held, was dispositive.

The majority acknowledged that the United States maintains a general trust relationship with Indian tribes, including the Navajos. But it declined to infer a conventional trust relationship with respect to water absent express language. “Indian treaties cannot be rewritten or expanded beyond their clear terms,” the Court wrote, quoting Choctaw Nation v. United States. And it noted that “it is not the Judiciary’s role to rewrite and update this 155-year-old treaty.” Congress and the President, the Court said, “may enact—and often have enacted—laws to assist the citizens of the western United States, including the Navajos, with their water needs.”

The Court also rejected three alternative arguments. First, the treaty’s establishment of the reservation as a “permanent home” did not imply a federal duty to secure water. Second, the treaty’s express provision of seeds and implements for three years demonstrated that the parties knew how to impose specific affirmative duties—and chose not to impose one regarding water. Third, the federal government’s purported control over reserved water rights could not, by itself, support a breach-of-trust claim; “the Federal Government’s liability” on such a claim “cannot be premised on control alone.”

The Winters doctrine survives—but it is not self-executing

Nothing in the majority opinion disturbed the reserved water rights doctrine established in Winters v. United States (1908). The Court reaffirmed that the federal government’s reservation of land for an Indian tribe implicitly reserves the right to use needed water from sources that arise on, border, cross, underlie, or are encompassed within the reservation. The Navajo Reservation lies almost entirely within the Colorado River Basin, and the Colorado, Little Colorado, and San Juan rivers border it. Under Winters, the Tribe has a right to water from those sources.

But a right is not a delivery schedule. The Winters doctrine establishes that reserved water rights exist; it does not establish their quantity, their priority date relative to state-law appropriators, or the infrastructure required to make them usable. Those questions require quantification—and quantification requires a forum.

The 2023 ruling did not answer those questions. It held that the federal government cannot be compelled, through a breach-of-trust suit, to answer them on the Tribe’s behalf. The Native American Rights Fund summarized the holding this way: the Court “agreed tribal nations indeed have water rights under the Winters doctrine” but “concluded there was no obligation to take steps to secure, or even identify, the water needed for the reservation.” That distinction—between the existence of a right and the existence of a duty to vindicate it—is the hinge on which the case turns.

The decision pathway: from Fort Sumner to the Supreme Court

The 1868 treaty was concluded at Fort Sumner, New Mexico, on June 1, 1868, ratified on July 25, and proclaimed on August 12. Article II set apart a reservation for the “use and occupation of the Navajo tribe.” Article XIII committed the Tribe to make the reservation its “permanent home.” Article VII provided seeds and agricultural implements for the first year, and for each succeeding year in which the head of a family continued to farm, up to two additional years, with values capped at one hundred dollars and twenty-five dollars respectively. The treaty contains no reference to water rights, the Colorado River, or the quantification of reserved water.

That silence is the textual foundation of the 2023 ruling. But the pathway to the ruling runs through a longer institutional history.

In 1952, Arizona sued California in the Supreme Court, invoking original jurisdiction over Colorado River water. The United States intervened and asserted claims on behalf of twenty-five tribes. It asserted claims to the Colorado River mainstream on behalf of only five tribes. The Navajo Nation was not among them; the United States limited the Navajo claim to the Little Colorado River, a tributary. The Navajo Nation sought to intervene in the proceedings before the Special Master. Its motion was denied at the United States’ urging. The Supreme Court’s 1964 decree in Arizona v. California excluded the Little Colorado River—and therefore the Navajo claim—from the adjudication, along with other tributaries.

In 2003, the Navajo Nation sued the Department of the Interior, the Secretary of the Interior, the Bureau of Reclamation, and the Bureau of Indian Affairs, bringing claims under the National Environmental Policy Act and a breach-of-trust claim for failure to consider the Tribe’s as-yet-undetermined water rights in managing the Colorado River. Arizona, Nevada, and various state water, irrigation, and agricultural districts and authorities intervened to protect their interests. The district court dismissed the complaint. The Ninth Circuit reversed in 2021, holding that the Tribe had stated a breach-of-trust claim premised on its treaties and its federally reserved Winters rights, especially when considered alongside the federal government’s pervasive control over the Colorado River.

The Supreme Court granted certiorari and reversed. The reversal was not a finding that the Navajo Nation lacks water rights. It was a finding that the 1868 treaty does not impose on the United States an affirmative duty to secure them.

Who gains, who loses, who decides

The ruling redistributes decision-making authority. That is its practical significance, and it is the question a political ecology lens should press hardest.

Who gains. The states that intervened against the Tribe—Arizona, Nevada, and Colorado—and the water districts and authorities that joined them gained procedural certainty. By foreclosing a federal breach-of-trust claim that could have compelled the Secretary of the Interior to assess Navajo water needs and develop a plan to meet them, the ruling reduces the risk that a federal court would order changes to Colorado River operations that affect existing state-law appropriators. The Court’s language about the “zero-sum situation” of allocating water in the arid West, and its instruction that courts “must stay in their proper constitutional lane,” signals deference to Congress and the executive—forums where state delegations and organized water interests have longstanding influence.

Who loses. The Navajo Nation loses a litigation pathway, not a water right. But the distinction matters less than it might appear. A right that cannot be quantified, scheduled, or delivered is a right that does not yet secure water for the roughly 170,000 people living on the reservation, many of whom lack running water. The Ninth Circuit’s 2021 opinion noted news reports that the Nation’s water shortage exacerbated COVID-19 risks because many homes lacked running water, making regular handwashing difficult. That is the human stakes of the procedural question.

Who decides. After 2023, the answer is: Congress, the executive branch, and—critically—the state court presiding over Arizona’s general stream adjudication. Arizona statute defines a “general adjudication” as an action for the judicial determination or establishment of the extent and priority of the rights of all persons to use water in any river system and source. The statute defines “person” to include an Indian tribe. That definition matters: it means the Navajo Nation can participate in the adjudication as a claimant. But participation is not the same as control. State general stream adjudications are notoriously slow, resource-intensive, and procedurally complex. The Tribe must litigate its Winters rights in a forum shaped by state water law, even though federal law determines the existence and scope of those rights.

The federal government, meanwhile, holds title to Navajo water rights in trust. The 2023 ruling confirms that it cannot be compelled to act affirmatively to secure them. That gap between title and duty is the structural feature the ruling entrenches. The Tribe depends on congressional willingness to fund water infrastructure and on executive willingness to assert its claims—neither of which is judicially enforceable under the majority’s reasoning.

What the ruling means for treaty rights on the Colorado River

The ruling does not weaken the Winters doctrine. It weakens the procedural mechanism by which tribes have sought to force the federal government to act on Winters rights. For other tribes in the Colorado River Basin, the implications are twofold.

First, the decision is potentially informative whenever a tribe seeks equitable relief based on the federal government’s breach of trust obligations. The Court’s requirement that a tribe identify specific rights-creating or duty-imposing language in a treaty, statute, or regulation will apply beyond water. Tribes seeking to compel federal action on any trust asset will need to point to express language, not general trust principles.

Second, the ruling leaves intact the pathways the Court itself identified. The majority noted that the Navajo Nation could assert its interests in water rights litigation, including by seeking to intervene in cases affecting those interests. The dissent, too, suggested that the Tribe could bring claims based on direct interference with its water rights and that principles of estoppel might preclude the United States from opposing future intervention requests. Those pathways are narrow, but they are not closed.

The broader lesson is about where water policy is made. The Supreme Court has said, in effect, that the allocation of water in the arid West is a political question in the constitutional sense—not because the Constitution commits it to the political branches, but because the judiciary will not infer duties the political branches have not expressly accepted. That is a choice about institutional competence. It is also a choice about who bears the burden of legislative inaction.

Practical implications for tribal water advocacy

For advocates and researchers tracking the aftermath of the ruling, several practical questions follow.

Document the quantification gap. The ruling did not quantify Navajo water rights. The general stream adjudication is the forum where quantification will occur. Tracking the docket, the parties’ claims, and the court’s scheduling decisions is essential to understanding when—and whether—the Tribe’s rights will be defined.

Track congressional appropriations. The Court noted that Congress and the President “may enact—and often have enacted—laws to assist the citizens of the western United States, including the Navajos, with their water needs.” The majority cited the Consolidated Appropriations Act, 2021; the Northwestern New Mexico Rural Water Projects Act; the Central Arizona Project Settlement Act of 2004; the Colorado Ute Settlement Act Amendments of 2000; and earlier statutes. Whether those laws are funded and implemented is now the central question for water delivery on the reservation.

Monitor federal assertion of Navajo claims. The United States holds Navajo water rights in trust. Whether the Secretary of the Interior asserts those rights in the general stream adjudication, and how vigorously, is a decision within executive discretion. The 2023 ruling confirms that the Tribe cannot compel that assertion through a breach-of-trust suit. It does not prevent the Tribe from advocating for it.

Watch for direct-interference claims. The dissent’s suggestion that the Tribe could bring claims based on direct interference with its water rights remains untested. Any federal or state action that physically diminishes Navajo water access could provide a vehicle for such a claim. The evidentiary burden would be high, but the pathway exists.

Frequently asked questions

Did the Supreme Court eliminate the Navajo Nation’s water rights? No. The Court reaffirmed that the 1868 treaty reserved necessary water under the Winters doctrine. It held that the treaty did not impose an affirmative duty on the United States to secure that water. The rights exist; the federal duty to vindicate them does not, at least not through the breach-of-trust claim the Tribe brought.

What is the correct case name? Arizona v. Navajo Nation, No. 21-1484, decided June 22, 2023, together with Department of the Interior v. Navajo Nation, No. 22-51. The case is not Navajo Nation v. Arizona.

Was the decision unanimous? No. The vote was 5–4. Justice Kavanaugh wrote the majority, joined by Chief Justice Roberts and Justices Thomas, Alito, and Barrett. Justice Gorsuch dissented, joined by Justices Sotomayor, Kagan, and Jackson. Justice Thomas filed a concurring opinion.

Does the ruling apply only to the Navajo Nation? The holding is specific to the 1868 treaty and the breach-of-trust claim the Tribe brought. But the reasoning—requiring express rights-creating or duty-imposing language—is potentially informative whenever a tribe seeks equitable relief based on the federal government’s breach of trust obligations.

Where will Navajo water rights be quantified now? The most likely forum is Arizona’s general stream adjudication, where the Navajo Nation can participate as a “person” under state law. Congressional action and executive-branch decisions are the other pathways the Court identified.

What to watch

The 2023 ruling is not the end of the Navajo water story. It is a change in venue. The questions that mattered before the ruling—how much water the Navajo Nation is entitled to, when it will receive it, and who will pay for the infrastructure to deliver it—remain unanswered. What changed is who has the power to answer them.

The Court’s majority placed that power in Congress and the executive. The dissent would have kept it in the courts. The practical consequence is that the Navajo Nation’s water future now depends on legislative appropriations, executive assertion of trust rights, and a state-court adjudication that will likely take years. For a political ecology of water, that is the finding that matters: the ruling did not resolve the allocation of risk. It redistributed the authority to decide who bears it.