UW News

March 16, 2023

Q&A: Navajo Nation water rights case an opportunity to reaffirm treaty obligations, UW law professor says

UW News


Against the backdrop of a longtime conflict among Western states over water in the Colorado River Basin, the U.S. Supreme Court on March 20 will take up the case of another significant – but often overlooked – claimant: the Navajo Nation.

The case, Arizona v. Navajo Nation, pits the treaty rights of the largest Native American reservation in the United States against water-rights claims by the state in which much of the reservation is located.

Monte Mills, professor of law at the University of Washington and director of the UW’s Native American Law Center, co-authored an amicus brief on behalf of 37 tribal nations, the Affiliated Tribes of the Northwest, the San Luis Rey Indian Water Authority and the National Congress of American Indians.

The brief, which Mills co-wrote with attorneys for the Native American Rights Fund and faculty from the University of Arizona and the University of Idaho, hinges on the Winters Doctrine, a 1908 decision by the U.S. Supreme Court that recognized that the establishment of a tribal reservation also reserved water necessary to fulfill the purposes of that reservation – even if water rights were not explicitly mentioned in the treaty.

Monte Mills

“Based on Winters, tribal nations have legal rights to water for their homelands, with a priority date of the creation of the reservation, which often means that tribal rights are quite senior compared to those of other water users,” Mills said. “Although the development of water resources and infrastructure across the West throughout the 1900s often overlooked or ignored tribal rights, the assertion of Winters rights by tribes (and the U.S. on tribes’ behalf) over the last half-century has helped resolve uncertainties based on the existence of those rights while ensuring many tribes could secure water for actual use, so-called ‘wet’ water rights, in addition the ‘paper’ rights guaranteed by the Winters Doctrine.”

Mills discussed the current case with UW News.


Q: States in the Colorado River Basin have been grappling with water supply and their own competing demands. How does this case fit into that context?

Monte Mills: The current conflict over water in the Colorado River Basin is the result of dwindling supply and the historical establishment of rights to water that overestimated the amount of water that might be available. Like the many other tribal nations in the Basin, the water rights of the Navajo Nation were largely overlooked in those negotiations and, therefore, rights were allocated among the Basin states with little thought given to the rights that the tribes would need. While other tribal rights in the Basin have been identified and resolved, the Navajo Nation continues to seek protection for its legal rights to water, particularly in the current era of scarcity. This case is part of those efforts.


Q: While this case specifically involves the Navajo Nation, there are implications for other tribes, as well. Please explain.

MM: The core of the Nation’s claim is that the United States has a duty to identify and protect the Nation’s as-yet unquantified and unadjudicated rights to water in the Colorado River Basin. That claim is rooted in the centuries-old recognition that – based on treaties, rulings of the U.S. Supreme Court, and acts of Congress – the United States has a trust relationship with tribal nations. Over the course of the evolution of federal Indian law, that trust relationship has come to define the federal-tribal relationship and is a critical component of the modern era of tribal self-determination. Here, the Navajo Nation is seeking to enforce those trust duties by asking a court to order the United States to take certain steps to protect the Nation’s rights to water.

Listen to UW Law’s Discovery podcast interview with Monte Mills

While the facts and context of this case are unique to the Navajo Nation, a decision by the Supreme Court in this case could help inform the scope and enforceability of the Indian trust doctrine.  


Q: A series of court rulings, as well as statements and policies by presidential administrations of both parties, have referenced the importance of treaty obligations. Is there reason to believe this time is different?

MM: It is hard to overstate the importance of treaties and the promises made therein, both to tribal nations and the United States. Those time-honored agreements are the backbone of federal Indian law and have been the basis on which the federal government has identified and fulfilled its duties to tribes. In addition, treaties provide a critical, quasi-constitutional connection between tribal sovereigns and their federal and state counterparts by providing a consensual basis on which tribal governments can base their intergovernmental relationships. It is no wonder, therefore, that the U.S. Constitution confirms that treaties are the “supreme law of the land,” and that the U.S. Supreme Court has established specific rules guiding the interpretation and enforcement of treaty promises.

Like many other tribal claimants before them, the Navajo Nation is asking the federal judiciary to interpret and enforce the terms of its historical agreements with the United States in accordance with those rules and standards. But, notwithstanding their importance, treaty obligations have often been set aside, ignored, overlooked, or outright abrogated by the United States, often in deference to other, non-tribal interests.

This case presents yet another opportunity for the United States Supreme Court to weigh the word and bond of the United States, pledged in treaties with the Navajo Nation, along with the rights and duties that flow from those guarantees, in light of their place in the Constitution, the Court’s precedent, and the competing claims and interpretations offered by those countering the Navajo Nation’s position.

For more information, contact Mills at mtmills@uw.edu.