This story was published in partnership with High Country News.

In early November, the U.S. Supreme Court agreed to hear a case brought by the Navajo Nation that could have far-reaching impacts on tribal water rights in the Colorado River Basin. In its suit, the Navajo Nation argues that the Department of Interior has a responsibility, grounded in treaty law, to protect future access to water from the Colorado River. Several states and water districts have filed petitions opposing the tribe, stating that the river is “already fully allocated.” 

The case highlights a growing tension in the region: As water levels fall and states face cuts amid a two-decade-long megadrought, tribes are working to ensure their water rights are fully recognized and accessible.

On average, 15 million acre-feet of water used to flow through the Colorado River every year. For scale, one acre-foot of water could supply one to three households annually. A century ago, states reached an agreement to divide that water among themselves. But in recent decades, the river has supplied closer to 12 million acre-feet. Scientists say water managers in the basin need to plan for closer to 9 million acre-feet per year, a 40 percent decrease in a water source that supports 40 million people, due to climate change and aridification.

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No states have made plans to accommodate this drop. Meanwhile, tribal nations are legally entitled to between 3.2 and 3.8 million acre-feet of ground and surface water from the Colorado River system.

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There are 30 federally recognized tribes in the river’s basin, and 12 of them, including Navajo Nation, still have at least some “unresolved” rights, meaning the extent of their rightful claims to water have yet to be agreed upon.

Map showing federally recognized tribal lands in the Colorado River Basin
Grist / Jessie Blaeser / Amelia Bates

Ultimately, Indigenous nations in the Colorado River Basin could be serious power brokers in crucial water negotiations to come — but they face historical, legal and practical obstacles. The Navajo Nation, for example, has rights to almost 700,000 acre-feet of water annually across New Mexico and Utah, along with unresolved claims in Arizona. But, because of a lack of infrastructure, up to 40 percent of Navajo households don’t have running water. For the Navajo Nation and other tribes with allocations in the basin, building and improving infrastructure means providing citizens with access to a fundamental human right: water.

But tribal water use is taken out of state allocations, meaning the more water tribes use, the less states have. It also means that states have less incentive to work with tribal leaders or recognize pending water rights claims. This conflict is not new. It has been built into a century of policies that have excluded and divested from Indigenous nations.

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Tribes often hold senior water rights, meaning their allocations are the last to be cut in a shortage, and states in the basin are beginning to reckon with this fact. A fundamental shift in how the river is governed — to a system that acknowledges tribes’ sovereignty and gives them greater say — will be key to sustainably and equitably distributing water in the years to come.

Tribes “need to be included in every one of those conversations and considered just like a state or the federal government,” Southern Ute Tribal Council Member Lorelei Cloud said at the annual Colorado River District Seminar in September. “You cannot discount us.”

Vertical stacked bar chart showing the proportion of water allocated to tribes under state allocations from the Colorado River Basin.
Grist / Jessie Blaeser / Amelia Bates

One barrier to equitable distribution is a glaring information gap: There is no definitive source of data on water usage among tribes in the Colorado River Basin. Historically, federal surveys have ignored tribal water use, and though tribal-led studies have begun to fill these gaps, the lack of data makes planning for a future river with shrinking flows impossible. 

“If you know how much water everyone has or is allocated, then you can come up with a comprehensive solution — not just management of the river but responses to climate change,” Heather Tanana (Diné), a professor of law at the University of Utah, said in an interview.

In Arizona, for example, nearly 70 percent of the state’s water allocation belongs to tribes, and nearly all the tribal nations with unresolved water rights in the basin have at least some territory in the state. According to a joint study by tribal nations and the federal government, 10 tribes in the basin, which hold the bulk of the recognized tribal water rights, are diverting just over half of what they’re entitled to — most of which is used for agriculture. It’s unclear what water availability would look like if these tribes had basic infrastructure to get water to their citizens, or if all tribes with unresolved rights settled their cases.

Horizontal stacked bar chart showing water diversions among one third of the tribes in the Colorado River Basin.
Grist / Jessie Blaeser / Amelia Bates

“My experience of negotiating water rights settlements in Arizona is that the state of Arizona very much approaches them as a zero-sum game,” said Jay Weiner, water counsel for the Quechan Indian Tribe and the Tonto Apache Tribe, which has been in settlement negotiations since at least 2014. That combative approach, he said, has persisted regardless of governor or political party. “It is something that seems to be deeply embedded in the fabric of Arizona and how it approaches Indian water rights settlements.”

In February, the federal government announced $1.7 billion for tribes to use for water settlements. That means more tribal citizens and communities could have access to water. It also means that states will have to work with tribes to plan for the future and adapt to climate change.

In some places, tribes and communities have already been moving in that direction, working together to find place-based solutions that use the resources and infrastructure at hand. The Pascua Yaqui Tribe and the city of Tucson, Arizona, have an intergovernmental agreement for Tucson to store and deliver potable water for the tribe, which doesn’t have the infrastructure to do so on its own. Such partnerships will only become more essential as drought and aridification continue to stress the region.

“If folks work together and partner together, the opportunity to solve the problem, I think, is enhanced,” said Robyn Interpreter, an attorney who represents the Pascua Yaqui Tribe and the Yavapai-Apache Nation in their water rights claims.

Timeline from 1908 to 2022 showing different historical events related to Indigenous water rights
Grist / Amelia Bates / Jessie Blaeser / Joseph Lee / Anna Smith

The federal Navajo-Gallup Water Supply Project, which is building $123 million in infrastructure, is another promising example. The goal of the project is to construct water plants and a system of pipes and pumps that will deliver water to the Navajo Nation, the Jicarilla Apache Nation, and the city of Gallup, New Mexico. Crystal Tulley-Cordova, a principal hydrologist for the water management branch of the Navajo Nation Department of Water Resources, said in an interview there is a new willingness to collaborate, owing to both the severity of the situation and non-tribal water users’ realization that they must work with tribes. “Now there’s a greater desire to be able to work together. So I’m encouraged by that,” she said.

Meanwhile, tribal nations are also making progress in securing their access to water. In May, the Navajo Utah Water Rights Settlement Act was finalized, granting the Navajo Nation 81,500 acre-feet of water in Utah and authorized $220 million in federal funds for water infrastructure projects. “Our families celebrate this moment in history after decades of fighting for the Navajo Utah Water Rights Settlement,” Navajo Nation Council Delegate Charlaine Tso said in a statement at the time. “It is clear drought conditions are affecting water levels across the country. Many of our elders haul drinking water from miles away while we work to get proper water infrastructure projects completed. This settlement allows us to begin connecting our water lines to the most rural areas.”

However, tribes still have no direct means of governance over the river, and, as seen in the Navajo water rights case headed to the Supreme Court, states continue to fight tribal communities seeking access to water.

Last fall, more than 20 tribes signed a letter to Interior Secretary Deb Haaland in which they pressed for direct, sustained involvement in re-negotiating the guidelines that manage the river, which are set to expire in 2026. In Albuquerque, New Mexico, last March, Haaland and Bureau of Reclamation leadership met with tribal leaders and “committed to transparency and inclusivity for the Tribes when work begins on the post-2026 operational rules,” according to a spokesperson for the Department of the Interior.

“It’s the job of political imagination to see what’s possible,” Andrew Curley (Diné), an assistant professor of geography at University of Arizona, said in an interview. “That’s something that we collectively, not just Native nations but led by Native nations, can start to articulate. What is a different vision of the river than what has been put into law and these congressional acts and Supreme Court decisions over the years?”