chevron-down Created with Sketch Beta.


November/December 2023

The Supreme Court’s decision in Arizona v. Navajo Nation: A tale of scarce water and treaty rights in the Southwest

Rita P Maguire and Nicole D Klobas


  • Addresses how the case Arizona v. Navajo Nation reaffirms that the federal government can only incur a fiduciary obligation to a tribe if it expressly accepts that fiduciary duty by treaty, statute, or regulation.
  • Provides background to the current litigation, spanning two decades.
  • Elaborates on how this case was about the Navajo Nation’s desire to obtain a federal reserved right to Lower Colorado River water.
The Supreme Court’s decision in Arizona v. Navajo Nation: A tale of scarce water and treaty rights in the Southwest
Anjelika Gretskaia via Getty Images

Jump to:

On June 22, 2023, the high court issued a 5-4 ruling in the consolidated cases of Arizona v. Navajo Nation and Navajo Nation v. U.S. Department of the Interior. The Court denied the Navajo Nation’s effort to enjoin certain federal actions involving the operation of the Lower Colorado River (LCR), which begins at Lee Ferry, Arizona, between Lake Powell in the Upper Basin of the Colorado River and Lake Mead in the Lower Basin of the Colorado River. The Court’s ruling is important because it reaffirms that the federal government (government) can only incur a fiduciary obligation to a tribe if it expressly accepts that fiduciary duty by treaty, statute, or regulation.

The Navajo Nation filed suit in 2003 seeking to compel the secretary of the interior (secretary) to assess the Nation’s water needs on its reservation in Arizona, develop a plan to secure the water needed, and manage the LCR to avoid harm to the Nation’s unquantified water rights. Three states and multiple water providers intervened due to the threat these claims presented to the security and stability of the allocations awarded by the Supreme Court in a prior landmark case, Arizona v. California, 373 U.S. 546 (1963), which allocated water from the mainstream of the LCR among the states of Arizona, California, and Nevada, and five Indian tribes

The Navajo Nation was among 25 tribes represented by the government in the Arizona v. California proceedings but ultimately, was not awarded rights to the mainstream of the LCR. The Supreme Court limited allocations to the river’s mainstream (excluding its tributaries) because the Boulder Canyon Project Act (45 Stat. 1057 codified at 43 U.S.C. §§ 617–619b (1928)), on which the opinion relied, dealt exclusively with mainstream water. Arizona v. California, 373 U.S. 546, 567–75. Instead, the government brought claims on behalf of the Navajo Nation to the Little Colorado River, a tributary of the Colorado River that crosses the portion of the reservation in Arizona.

The current litigation spanned two decades starting with a complaint by the Navajo Nation against the secretary in her role as water master (or manager) of the LCR, alleging a single count for breach of trust duties based on two treaties between the Navajo Nation and the United States and six allegations of violation of the National Environmental Policy Act (NEPA). Twice, the complaint was dismissed by the U.S. District Court of Arizona for lack of subject matter jurisdiction, and twice the Ninth Circuit Court of Appeals remanded the case with instructions. In 2017, the Ninth Circuit affirmed the lower court’s dismissal of the NEPA claims, but held that the Navajo Nation’s complaint properly stated a breach of trust claim premised on its: 1. federal reserved rights pursuant to a prior Supreme Court case, Winters v. United States, 207 U.S. 564 (1908), 2. treaties with the United States, and 3.the secretary’s “pervasive control” over the LCR. Navajo v. U.S. Department of Interior, 876 F.4th 1144, 1173 (9th Cir. 2017).

In 2022, the Court of Appeals again remanded the case back to the District Court with instructions to “fully consider the [breach of trust] claim on its merits. . . .” Navajo Nation v. USDOI, 26 F.4th 794 (9th Cir. 2022). A group of nonfederal intervenor states including the state of Arizona and various water districts, the state of Nevada and various water districts, various water districts in California, and the state of Colorado filed a petition for certiorari challenging the lower court’s jurisdiction over the Navajo Nation’s complaint and the tribe’s claim that the government has a fiduciary duty to secure water for its reservation. The federal defendants filed a separate petition for certiorari limiting its challenge to the Ninth Circuit’s holding that a “fiduciary duty exists.” The Court granted both petitions and consolidated the cases for argument heard in March 2023.

The Navajo Nation’s breach of trust claim was primarily based upon its 1868 Treaty with the United States and the common law reserved water rights doctrine established by the Supreme Court in Winters, 207 U.S. at 576–57. The Navajo Nation cited the 1868 Treaty, which returned the tribe to their original homeland, as a source of positive law sufficient to impose a fiduciary duty on the government to secure water for the reservation. In its response to the opening briefs filed by the federal defendant and the intervenors, the Navajo dropped two of its claims for secretarial management of the LCR that takes into consideration the Navajo’s unqualified rights; and also mitigation of any harm to such rights as a result of secretarial management of the LCR. Because the Ninth Circuit decision and each of the previous judicial rulings were based upon a four-part claim, there was significant confusion among the justices as to what was before the Court. This confusion is reflected in both the Court’s majority and dissenting opinions.

In Arizona v. Navajo Nation, 599 U.S. 555 (2023), Justice Kavanaugh, writing for the Court’s majority, disagreed with the breach of trust claim, pointing out that the 1868 Treaty “set apart” a reservation for the Navajo Nation for its “use and occupation” but contained no “rights-creating or duty-imposing” language that imposed a duty on the United States to “take affirmative steps to secure water for the Tribe.” 599 U.S. at 564____ (citing United States v. Navajo Nation, 537 U.S. 488, 506 (2003) (secretarial approval of a coal lease between the Navajo and third party under the Indian Mineral Leasing Act did not create fiduciary obligations on the government to the tribe)). To impose such a duty, the text of a treaty, statute, or regulation must expressly impose it. Id. (citing United States v. Jicarilla Apache Nation, 546 U.S. 162, 173–74, 177–78 (2011)). A long line of decisions from the Supreme Court and the Ninth Circuit clearly establishes that the government owes judicially enforceable duties to a tribe “only to the extent it expressly accepts those responsibilities.” But as the Court noted, the Navajo Nation’s treaty contains no language requiring the Government to secure water for the reservation. Quoting Choctaw Nation v. United States,318 U.S. 423, 432 (1943), the majority concluded that “Indian treaties cannot be rewritten or expanded beyond their clear terms.” 599 U.S. at 565.

Alternatively, the Navajo Nation argued that the common law Winters Doctrine, establishing federally reserved water rights, was sufficient to impose a duty on the government to supply water from the LCR to the reservation. But the majority pointed out that Winters only recognized the government’s implicit reservation of water “from various sources––such as groundwater, rivers, [etc.] that border, cross, underlie, or are encompassed within the reservation.” Winters v. United States, 207 U.S. at 576–57. The Treaty of 1868 did not reference an affirmative duty on the government to provide water to the tribe. 599 U.S. at 567.

The Navajo Nation also asserted that secretarial control over federal reserved water rights was sufficient to impose a duty to secure water for its reservation. The Court disagreed, holding that the government’s liability on a breach-of-trust claim “cannot be premised on control alone.”

In a dissent authored by Justice Gorsuch, four members of the Court argued that the tribe’s complaint sought simply to “compel the Federal Defendants to determine the water required to. . . . fulfill the promise[s] made to them under the Treaty of 1868.” 599 U.S. 594 (citing the Navajo’s Response Brief to the Court). However, this description ignored the larger scope of the Navajo Nation’s complaint as it proceeded through the lower courts. In striking down the Ninth Circuit’s opinion in its entirety, the Court majority recognized that the Navajo Nation “may be able to assert the interest they claim in water rights litigation . . . by seeking to intervene in cases that affect their claimed interests.” Id. at 568–69.

Although the Court’s ruling was limited to a breach of trust claim, the intervenors argued that at bottom, this case was about the Navajo Nation’s desire to obtain a federal reserved right to Lower Colorado River water. The intervenors argued that any such claim can only be heard pursuant to a motion to reopen the Consolidated Decree in Arizona v. California due to the Court’s retained and exclusive jurisdiction over the allocation of water from the LCR.

Many see this case as a preservation of the status quo. If the Navajo Nation wishes to pursue a federal reserved right claim to the flows of the LCR, then it must ask the Supreme Court to revisit its long-standing decision in Arizona v. California or, as the majority suggested, ask Congress to find a legislative solution “in light of the competing contemporary needs for water.” 599 U.S. at 567.