Arizona v. Navajo Nation

LII note: The U.S. Supreme Court has now decided Arizona v. Navajo Nation.


Is there a trust relationship between the Navajo Nation and the U.S. government and no jurisdictional prohibitions such that the Navajo Nation can compel the U.S. Government to assess and manage the Nation’s water interests in the Colorado River?

Note: The authors mirror the parties’ and courts’ use of the term “Indian” as a legal term in this Preview.

Oral argument: 
March 20, 2023

This case asks the Supreme Court to consider whether there is a trust relationship between the Navajo Nation (“the Nation) and the U.S. government regarding the Nation’s water rights. Arizona contends that the Nation’s claim infringes upon the Supreme Court’s retained and exclusive jurisdiction over the allocation of water from the Colorado River mainstream in Arizona v. California. Furthermore, Arizona argues that the Nation has failed to state a cognizable breach-of-trust claim because the Nation did not specify a source of law establishing the government’s fiduciary duty. The Nation counters that the claim does not fall under the Supreme Court’s reserved jurisdiction because the Nation did not seek a quantification of its rights to the Colorado River mainstream. The Nation further contends that it has identified provisions in treaties, statutes, and the Winters doctrine to establish the trust duty on the federal government to ensure an adequate water supply for the Navajo Reservation. The outcome of this case will have far-reaching implications for the Navajo Nation’s water resources, the stability of water rights, and the water allocation system.

Questions as Framed for the Court by the Parties 

(1) Whether the opinion of the U.S. Court of Appeals for the 9th Circuit, allowing the Navajo Nation to proceed with a claim to enjoin the secretary of the U.S. Department of the Interior to develop a plan to meet the Navajo Nation’s water needs and manage the mainstream of the Colorado River in the Lower Basin so as not to interfere with that plan, infringes upon the Supreme Court’s retained and exclusive jurisdiction over the allocation of water from the LBCR mainstream in Arizona v. California; and (2) whether the Navajo Nation can state a cognizable claim for breach of trust consistent with the Supreme Court’s holding in United States v. Jicarilla Apache Nation based solely on unquantified implied rights to water under the doctrine of Winters v. United States?


The Navajo Nation (“the Nation”) is a federally recognized Indian tribe that signed the 1849 Treaty and the 1868 Treaty with the United States. Navajo Nation v. USDOI at 8. The Nation’s Reservation sprawls across Arizona, New Mexico, and Utah, and lies almost entirely within the drainage basin of the Colorado River. Id. at 9. Since much of the land in the Colorado River drainage basin is arid, water competition is fierce. Id. The Nation's shortage of water has in part caused exacerbation of the risks from COVID-19. Id.

Winters v. United States is a landmark U.S. Supreme Court case that established Indian reserved water rights in the United States. Id. at 13. The Winters Court granted the tribe federally reserved rights to the Milk River, setting a precedent for subsequent decisions that reaffirmed the scope of Indian reserved water rights and established that tribal water rights may take priority over state water rights. Id.

In a previous jurisdiction action, Arizona v. California, the Court entered a decree that allocated water rights in the Colorado River. Id. at 11. The Arizona Court reaffirmed the Winters doctrine, which stated that water from the Colorado River was crucial for the survival of Indian people, animals, and crops on desert lands, and awarded five tribes federally reserved water rights. Id. at 14. While the United States had intervened in that action and made claims on behalf of several tribes, it did not assert any claims for the Nation regarding the river's mainstream, but only for a tributary. Id.

In 2003, the Nation filed an initial complaint in the United States District Court for the District of Arizona against the United States Department of the Interior, the Secretary of the Interior, the United States Bureau of Reclamation, and Bureau of Indian Affairs (collectively “Petitioners”). Id. at 7. The complaint alleged a violation of the National Environmental Policy Act (“NEPA”) and a breach of trust claim for failure to consider the Nation's undetermined water rights. Id. Several entities, including the State of Arizona (“Arizona”), intervened in the case as defendants. Id. In 2017, the United States Court of Appeals for the Ninth Circuit heard the case on appeal and ruled that the Nation lacked standing to bring NEPA claims but could proceed with its breach-of-trust claim, which was not barred by sovereign immunity. Id. The case was remanded to the district court. Id.

The district court determined that it lacked authority to rule on the breach-of-trust claim due to the claim falling within the Supreme Court's reserved jurisdiction as per the Arizona v. California decree. Id. The Ninth Circuit reversed. Id. at 36. First, the Ninth Circuit concluded that the Nation's claim did not seek a quantification of its rights to the Colorado River mainstream, which would fall within the Supreme Court's jurisdiction. Id. at 21. Second, the Ninth Circuit rejected the argument that the Nation could not assert a breach-of-trust claim due to a lack of specific treaty, statute, or regulation. Id. at 33. The Ninth Circuit held that the Nation had identified provisions in its treaties, statutes, executive orders, and the Winters doctrine that imposed fiduciary obligations on the federal government to ensure an adequate water supply for the Navajo Reservation. Id.

The Petitioners then appealed to the Supreme Court. On November 4, 2022, the Court granted Petitioners’ certiorari petition. The case was consolidated with Dep’t of Interior v. Navajo Nation.



The States of Arizona, Nevada, Colorado, The Metropolitan Water District Of Southern California, and other entities (collectively “Arizona”) contend that the Navajo Nation (“the Nation”) has failed to establish a violation of a trust relationship between the Nation and the U.S. Government (“Government”). Brief for Petitioner, Arizona et al. at 35. Although Arizona acknowledges that the Government has had a general trust relationship with Indian nations since the country’s inception, Arizona contends that the Nation’s water claims do not require affirmative action on the Government’s part. Id. at 34. Arizona contends that the Government has no responsibility to actively assess the Nation’s water needs or to develop a plan to meet such needs. Id. at 26. Rather, Arizona argues that neither Congress nor the Executive has specifically adopted a relevant measure to establish such a relationship. Id. Arizona further argues that, at most, the Nation and the Government might have a “bare” or “limited” trust relationship, which does not impose a stringent fiduciary burden on the Government. Id at 34.

Arizona further argues that the Nation has not stated a cognizable claim because the Nation failed to point to a substantive legal basis for the Government’s alleged fiduciary duty. United States v. Navajo Nation; Brief for Petitioner at 27. Arizona also contends that the Nation must identify a specific trust relationship even where the Nation is trying to claim non-monetary relief. Brief for Petitioner at 29. Arizona notes that, in cases such as United States v. Jicarilla Apache Nation, the parties did not seek monetary damages, yet the Court nonetheless understood the trust relationship to require the Government’s explicit acceptance of particular duties. Id. at 28.

The Navajo Nation argues that it has stated a valid claim based on broken treaty obligations and the Nation’s trust relationship with the Government. Brief for Respondent, Navajo Nation et al. at 16. The Nation argues that several treaties with the Government require the Government to provide sufficient waters for the reservation. Id. For example, the Nation asserts that the 1868 Treaty language guaranteeing the Navajo people a “permanent home” on the reservation implies that the permanent home has sufficient water. Id. at 22. The Nation also notes that treaty language requires that the Navajo people give up all external claims to land outside the reservation–further implying the need for a water guarantee by the Government so that the Nation can pursue agriculture on the reservation. Id.

The Nation further emphasizes that the treaties must be read according to the way that the Navajo people would have understood them. Brief for Respondent at 17. The Nation argues that such an interpretation would favor tribal interests. Id. at 18. Any ambiguities, the Nation contends, should be resolved in favor of the Nation. Id. at 20. Further, the Nation also asserts that the trust relationship would not result in vague judicially-created obligations to Indian nations. Id. at 37. Rather, the Nation contends that the judicial analysis would consider each case individually and analyze the specific Indian nation and treaty situation. Id. at 37. In short, the Nation argues that if the Navajo people understood the treaties to be a promise of water as well as land, and if the United States knew that the Nation needed said water, that water on the Reservation was “what the parties bargained for” when they entered into the treaties. Id. at 35.


Arizona denies that the Winters doctrine guarantees the Nation water. Brief for Petitioners at 30. The Winters doctrine comes from the case, Winters v. United States, and states that federal reservations of Indian land include an implied amount of water necessary for the reservation’s wellbeing. Id. Arizona, however, refutes that the Winters doctrine guarantees water to the Navajo Nation because an implied water right is only a “limited” or “bare” trust. Id. at 34. Such implied rights, argues Arizona, cannot create the kind of affirmative duty required to mandate the Government’s assessment of the Nation’s water rights. Id. at 35. Further, Arizona argues that the Winters doctrine is common law, and that Supreme Court precedent has not recognized that common law can impose fiduciary duties on the Government. Id. at 26.

Arizona also refutes the Nation’s argument that the 1868 Treaty imposes duties on the Government. Brief for Petitioner at 35. The Federal Parties, also petitioners in this case, argue that just because the 1868 Treaty encourages agriculture and the cultivation of land does not mean that the 1868 Treaty imposes a duty on the Government regarding the Nation’s water supply. Brief for Petitioner, Federal Parties at 38–39. Arizona posits that the Treaty’s silence regarding water-related rights prevents the Nation from asserting the present claims for equitable relief. Id. at 39.

The Nation disagrees with Arizona and argues that the Winters doctrine should apply. Brief for Respondent at 20. The Nation contends that Supreme Court precedent has long understood treaty guarantees of a permanent Native homeland as guaranteeing sufficient waters for the reservation. Id. The Nation also notes that other treaties between Indian nations and the Government have established an implied duty for the Government to ensure Indian water interests, even where the treaty did not explicitly mention water. Id. Further, the Nation points to the historical record which reveals that the Navajo people were forced by the Government off fertile lands and into the arid, unsuitable living conditions of the contemporary Reservation in the Bosque Redondo region. Id. at 23. The Nation argues that the Government knew that the Nation needed appropriate water resources to survive, and that the Treaties were written with such concerns in mind. Id.

The Navajo Nation further contends that both the 1849 and 1868 Treaties impose affirmative duties on the Government regarding the Nation’s water interests. Brief for Respondent at 24. The Nation argues that both treaties support the provision of sufficient water for the Nation. Id. at 21. The Nation interprets the language of the 1849 treaty, stating that the Government should secure the “permanent prosperity and happiness” of the Nation, as a guarantee of water as well as land. Id. The Nation also argues that the language of the 1868 Treaty was meant to encourage agriculture, which is not possible without proper water supply. Id. at 22.


Arizona contends that compelling the Government to provide the Nation water from the Colorado Basin would violate the Consolidation Decree (“the Decree”) established in Arizona v. California. Brief for Petitioner at 20. Arizona contends that the Decree generally forbids the Government from releasing waters in its control from the Colorado River absent a valid contract or designation as a rights holder. Id. at 36, 42. Arizona notes that the Nation lacks the relevant contracts and was not a named a relevant rights holder. Id. Further, Arizona contends that Article IX of the Decree reserves exclusive jurisdiction over this matter to the Supreme Court, and that lower courts cannot intrude by adjudicating water rights. Id. at 21–23. Arizona concludes that allowing such cross-jurisdictional action would result in chaos. Id. at 23.

The Nation disagrees and argues that the Government should be allowed to assess the Nation’s water needs without violating the Decree or trespassing on the Supreme Court’s jurisdiction. Brief for Respondents at 44. The Nation contends that they are not seeking the mere quantification of their water rights. Id. Rather, the Nation contends that they are simply asking the Government to determine the scope of their water needs, regardless of where that water originates. Id. at 44–45. Thus, the Nation argues that their claim does not pertain to the subject matter of the Decree and does not trigger the provisions therein. Id. at 44.



Western Water Users and Trade Associations (“WWUTA”), in support of Arizona, argue that if the Nation’s lawsuit is allowed to proceed, it will lead to a reduction in the available water for other users. Brief of Amici Curiae Western Water Users and Trade Associations, in Support of Petitioners at 15. The WWUTA note that this reduction will come at the expense of existing allocation holders, including those who receive water from the Central Arizona Project. Id. The WWUTA point out that this project supplies water to over 5 million people, which is more than 80% of Arizona’s population and is critical for a number of industrial and agricultural purposes that are vital to the state's economy. Id.

The DigDeep Right to Water Project and Utah Tribal Relief Foundation (“DigDeep”), in support of the Nation, points out that the reduction of water can be justified by the significant difference in water availability and use between the Nation and the states that surround it. Brief of Amici Curiae DigDeep Right to Water Project and Utah Tribal Relief Foundation, in Support of Respondents at 10. DigDeep notes that residents of the Nation use an average of only 7 gallons of water per day for basic needs such as drinking and cleaning, which is significantly less than the average American who uses around 88 to 100 gallons of water per day at home. Id. at 9. DigDeep states that this lack of water access has had a disproportionate and devastating impact on the Nation, contributing to negative health outcomes and dire economic conditions. Id. at 22, 23, 29.


The WWUTA argue that allowing the Nation’s lawsuit to proceed will have serious negative consequences for the stability of water rights, not just in Arizona but across the western United States. Brief of Western Water Users and Trade Associations at 12. The WWUTA contend that water is a scarce resource in much of the region, and the development of the West has always required extensive and careful water management, both in terms of physical infrastructure and legal regimes. Id. at 8. Therefore, WWUTA assert that it is crucial for states and private water users in water-scarce areas to have confidence in their water rights on a prospective basis, or else it could jeopardize existing investments. Id. at 3.

Tribal Nations and Indian Organizations, in support of the Nation, argue that certainty can only be achieved by upholding tribal water rights, rather than weakening them. Brief of Amici Curiae Tribal Nations and Indian Organizations, in Support of Respondents, at 31. The Tribal Nations and Indian Organizations note that when states recognize and take steps to assess and enforce tribal water rights, it enables them to manage water resources more accurately and determine the availability of water for all users. Id. The Tribal Nations and Indian Organizations point to Montana as an example of successful resolution of water rights issues. Id. at 31-32. The Tribal Nations and Indian Organizations note that the Reserved Water Rights Compact Commission was able to settle the water rights of every Tribal Nation in the state in compliance with the Montana Supreme Court's recognition of tribal reserved rights, and all but one of those settlements have been ratified by Congress and decreed by the Montana Water Court. Id.


Written by:

Carolyn Click

Ruihao Lin

Edited by:

Tori Staley

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