Arizona’s Tribal water strategy

The year 2026 looms large on Arizona’s horizon as the expiration date for the current Colorado River operating guidelines. Negotiations are underway to rewrite the “law of the river,” and Arizona could lose up to 100% of its share of CAP canal water from the River — including 40% of Phoenix’s water supply.

Thirty federally recognized tribes span the Colorado Basin, including many in Arizona, and together they have legal rights to roughly a quarter of the river’s flow. In theory, that’s more water than Nevada and New Mexico combined use.

But historically, these tribes were excluded from negotiations among River water users — no Tribal nation had a voice in the 1922 Colorado River Compact, and their “paper water” from the Colorado was often inaccessible and went unused while states grew.

In Arizona, numerous tribes only secured their water settlements in the past few decades, and some — like the Navajo Nation and Hopi Tribe — are still fighting for full recognition of their claims. For tribes, the River’s restructuring in 2026 is an opportunity to further assert their water sovereignty. For Arizona at large, it’s a chance to forge more partnerships with tribes — partnerships that could make or break the state’s water security.

The thing about Tribal water rights is they are some of the most secure, most “senior,” in the Basin. In contrast, Arizona’s CAP canal water rights are the most vulnerable, most “junior.”

So, Tribal leaders — historically sidelined and seen as a threat to Arizona’s water security — are now more welcome in negotiating rooms. Today, we’ll explain how it all works and how it went down.

Collectively, tribes hold rights to roughly one-quarter of the Colorado River’s annual water supply — a volume on par with some entire states’ allocations. In Arizona, Tribal nations collectively possess about half of the state’s 2.8-million acre-foot Colorado River allocation.

For many tribes, “paper water,” their legal entitlement, does not equal “wet water” delivered — much of that water remains unused without delivery infrastructure.

Arizona tribes also bank water in Lake Mead via “Intentionally Created Surplus” agreements — for example, the Gila River Indian Community stored 125,000 acre-feet in the reservoir in 2022, sometimes fallowing their agricultural fields in exchange for subsidies​. This conservation is allowing Central Arizona to grow and keeping Lake Mead from declining as rapidly as it otherwise would.

It wasn’t overnight that Arizona’s Tribal nations secured half of the state’s River water supplies — and the key to their ongoing efforts rests on a century-old Supreme Court decision. Here are some milestones in the saga.

1908 – Winters v. United States: Over a century ago, the U.S. Supreme Court held that when the federal government created an Indian reservation, it implicitly reserved sufficient water to fulfill the reservation’s purpose​. The “Winters doctrine” gave tribes enduring senior rights: a tribe’s water right dates to the reservation’s establishment (often making it senior to later users) and is not lost by non-use. The Winters case became the foundation for all subsequent Indian water claims, ensuring that tribes’ reserved rights must be recognized.

1964 – Arizona v. California: The Supreme Court settled the interstate fight over the Colorado River, confirming Arizona’s 2.8 million acre-foot annual share. The 1964 decree also decided that much of the River’s water must be allocated to five tribes in the Basin. Over subsequent decades, those rights were made more “perfect” or specific, and in some cases, expanded.

1978 – Ak-Chin Settlement: The first Tribal rights settlement for Basin water to be implemented was the Ak-Chin Indian Community Settlement Act. After negotiations, Congress promised the small O’odham community 85,000 acre-feet of groundwater, limited to agricultural use. In 1984, after the government failed to deliver the promised water, the Tribe threatened to sue for damages. In response, Congress resettled the rights, replacing the 80,000 acrefeet of groundwater rights with 75,000 acrefeet of CAP water from the Colorado, and expanding CRIT’s allowed usages of that water.

1982 – Tohono O’odham: In southern Arizona, the Tohono O’odham Nation’s River claims to 66,000 acrefeet of water were addressed by the 1982 Southern Arizona Water Rights Settlement Act, which provided the tribe with CAP water for its reservation lands near Tucson — later supplemented in 2004.

1988 - Salt River Pima-Maricopa Indian Community: In the Valley, this settlement awarded 122,400 acrefeet to the Tribe and established a complex and creative system of water exchanges, lease-backs and storage arrangements (including effluent exchange) between two Tribes, seven Phoenix area cities and three irrigation districts. The deal ensured a dependable supply from the Salt and Verde rivers (and some CAP water) through agreements with the Salt River Project and local cities​.

1990 – Fort McDowell Yavapai Nation: After contentious negotiations, this settlement awarded 36,350 acrefeet of Verde River water plus funding for water projects.

2004 – Gila River Indian Community: The GRIC Tribal settlement was one of the largest under the Arizona Water Settlements Act, providing a water budget of 653,500 acre-feet per year from the CAP, Gila River, Salt River and other sources. The settlement ended decades of bitter litigation over Gila River water rights. GRIC agreed to cap its claims in exchange for infrastructure funding and the ability to lease or bank unused water, making the community a key player in regional water management.

2006 – Colorado River Indian Tribes (CRIT): The CRIT reservation comprises Mohave, Chemehuevi, Hopi and Navajo peoples. They’ve been awarded 719,248 acre-feet of Colorado River water with an 1865 priority date. For decades, much of that entitlement went unused on CRIT’s reservation — effectively flowing to other users for free. In 2023, Congress passed a law allowing CRIT to lease or store its water within Arizona, turning the “paper” water into a marketable asset.

2010 – White Mountain Apache Tribe: In eastern Arizona, the WMAT reservation finalized a settlement securing 74,000 acrefeet of water from the Salt River, a tributary of the Colorado, and 25,000 acrefeet of leasable CAP water.

In 2023, the Hualapai Tribe won 4,000 acrefeet of CAP water in a settlement, and the Northeastern Arizona Indian Water Rights Settlement Act of 2025 would ratify water rights for the Navajo Nation, Hopi Tribe and the San Juan Southern Paiute Tribe. Other tribes, like the Cocopah, still don’t have delivery infrastructure for their settled water rights.

The 1922 Colorado River Compact was negotiated by seven states with no Tribal input. In subsequent decades, state leaders often resisted Tribal claims.

In November 1953, U.S. Attorney General Herbert Brownell and the DOJ filed a petition in the case of Arizona v. California — a decades-long case forming much of the “law of the river” — asserting that Tribal water rights were “prior and superior” to all other users in the Colorado River Basin.

Arizona Gov. John Howard Pyle and all of the Colorado Basin states were indignant. Pyle held a meeting with Brownell, other regional politicians put pressure on D.C., and the petition was removed four days later. After eliminating the “prior and superior” language from the petition, the feds refiled it a month later.

After being snubbed by the federal government, it was the Tribes’ turn to feel indignant. The largest tribe in the Colorado Basin — the Navajo Nation — sent a stark warning to then–Attorney General Robert F. Kennedy in 1961, saying that denying the Nation water would cripple its future, and the Nation would begin the slow work of clawing back what was theirs all along — guaranteed by treaties older than Arizona’s statehood.

The Nation and other Tribes started making good on that threat. The lawsuits got filed, and the states were on the defensive. Knowing that Brownell’s “prior and superior” claims were grounded in case law, Western politicians came to the negotiation table.

Phoenix’s law department created an adjudication office in 1988 to work with the GRIC and other tribes in the state. And former Arizona U.S. Sen. Jon Kyl helped pass settlements for at least seven tribes.

In recent years, Arizona’s leaders have actively supported Tribal water rights. Gov. Katie Hobbs praised CRIT as “a vital partner… in water conservation,” calling its water supply “invaluable”.

Today, Tribal water fuels farms, homes, and riparian habitat restoration across Arizona. But disparities persist — around 40% of Navajo Nation households still lack running water.

So the Basin’s tribes are angling to make sure their voices are heard, officially, at Colorado River negotiations. As it is, the federal government acts as the official representative of Tribes, but Tribal leaders say meaningful representation “just hasn’t happened historically.”

But the Tribes also have more political power to leverage today.

In recent drought deals, for instance, the GRIC conserved 125,000 acre-feet in Lake Mead in 2022, earning $50 million in federal compensation, and forestalling cutbacks to Phoenix’s CAP water supply. Other tribes, like the San Carlos Apache and Quechan, have struck similar agreements. Some also lease water to cities or farms — and with Congress now allowing the Colorado River Indian Tribes to lease water off-reservation, Arizona’s water market is entering a new era.

The tribes of Arizona, with their historic senior water rights, might be the most powerful players in keeping Colorado River water flowing into Arizona’s future.

Water SNAFU: The phrase of the day at Valley Partnership’s 2025 Water Summit Luncheon was, “We are running out of water. We have all the water we need.” And that pretty much sums up the mixed messages we constantly hear from Arizona. It’s an emergency and something must be done. But don’t worry — we’ve got plenty of water.

Make America Flow Again: A bipartisan bill, the Advancing Water Reuse Act, has been introduced in Congress by Reps. Darin LaHood (R-IL), Claudia Tenney (R-NY), Linda Sanchez (D-CA), and Brad Schneider (D-IL), aiming to create tax incentives for industrial water users to adopt water recycling for operations.

No time to waste: With new “advanced water purification" standards for potable water now set in rule, the Arizona Department of Environmental Quality envisions that Arizona could produce 112,000 acrefeet of drinkable recycled wastewater every year, the Capitol Times’ Kiera Riley reports. For scale, that’s about one-third of Phoenix’s annual water demands, and Phoenix has already begun rehabilitating the Cave Creek Water Reclamation Plant for advanced water purification. Scottsdale wants to implement the new rules as early as 2029, 12News’ Jen Wahl reports.

More crop per drop: A shrub native to Mexico’s Chihuahuan Desert, guayule (“why-yoo-lee”), might be one of Arizona’s crops of the future due to its drought tolerance. The plant can be processed into a kind of rubber that creates less toxicity in its production, Naomi DuBovis and Eleri Mosier write for the Republic. And it’s one of potentially many Mexican agricultural crops that might be studied and adopted by the U.S. under an international agreement.

Farm-to-tabled: Chair of the state senate Natural Resources Committee, T.J. Shope, didn’t get a floor vote for his ag-to-urban bill this year, but he says1 he still expects the bills to go up for a vote when the stakeholder process finishes. Meanwhile, Gov. Katie Hobbs’ Department of Water Resources is continuing to explore the concept with agency rule-making. The idea is to create a pathway for farmers to sell their land and water rights to urban or industrial developers. Knowing that, one day, agriculture will have to limit its water use in the state, many farmers would welcome the opportunity to sell their water while they still can.

Fighting the water war: Hobbs’ water policy advisor, Patrick Adams, spoke with the Capitol Times’ Reagan Priest about his job and why every morning he has to “strap on [his] armor to drive into the office.”

If Arizona’s imperiled water supplies are secured, it's not just new housing and growing food that’s at stake. Without water, we can’t continue to build taller water park slides, meditate on paddleboards at night, enjoy water lantern festivals, and send speedboats flying into the air and crashing while trying to break speed records.