The final week of October brought another escalation in the legal fight over Colorado River cuts, while Tribal leaders continued pushing for a major Arizona water rights settlement and new research showed that groundwater reserves across the Basin are also declining.
The Central Arizona Project moved to join Nevada’s lawsuit challenging the federal government’s new Colorado River operating plan.
KJZZ reported that CAP filed to join the lawsuit after the Arizona Department of Water Resources made a similar move earlier in October. The lawsuit argues that the federal plan places too much of the burden on Arizona, California, and Nevada while requiring no comparable mandatory reductions from Colorado, New Mexico, Utah, and Wyoming.
CAP operates the 336-mile canal that delivers Colorado River water to central and southern Arizona. Under the federal framework, CAP could face some of the deepest reductions because of its junior priority within Arizona’s Colorado River allocation.
CAP General Manager Brenda Burman said the agency had spent years trying to avoid litigation but ultimately decided it needed to defend its water rights and its interpretation of the laws governing the river.
The lawsuit also raises questions about the 1922 Colorado River Compact. CAP and other Lower Basin interests argue that the Upper Basin has obligations to deliver sufficient water downstream and that the new federal plan does not adequately enforce those requirements.
Interior Secretary Doug Burgum pushed back on Arizona’s legal challenge during a visit to the state.
ABC15 reported that Burgum warned that taking the issue before a judge could create additional risk for Arizona because of the state’s relatively junior priority compared with other Colorado River users. He said the federal government developed the operating plan after the seven Basin states failed to reach their own agreement.
Despite the legal disagreement, both federal and Arizona officials acknowledged that the central problem remains the same: the Colorado River is producing less water, and the Basin still needs a longer-term solution.
While those legal questions continue, Tribal leaders in northeastern Arizona are asking Congress to finalize one of the largest Tribal water settlements in the state.
The Arizona Capitol Times reported that leaders from the Navajo Nation, Hopi Tribe, and San Juan Southern Paiute Tribe urged Congress to approve the Northeastern Arizona Indian Water Rights Settlement Act.
The legislation would resolve outstanding water claims for the three Tribes, fund a pipeline from Lake Powell, and establish trust funds to help build water infrastructure.
For the San Juan Southern Paiute Tribe, the legislation would also establish a reservation the Tribe has sought for decades.
The settlement would allow the Navajo Nation and Hopi Tribe to lease portions of their Upper Basin Colorado River water to other Arizona users. Tribal and water leaders said the agreement could provide greater certainty for both Tribal communities and other Colorado River users.
The discussion again highlighted a recurring issue with Tribal water rights: having a legal right to water does not necessarily mean a community has the infrastructure needed to use it.
Groundwater is facing its own challenges.
The University of Arizona Water Resources Research Center highlighted a new study documenting sustained groundwater losses throughout the Colorado River Basin over the past two decades.
Researchers found that groundwater depletion accelerated after 2019, particularly during the 2020–2022 drought. Higher temperatures, reduced precipitation, and increased water consumption all contributed to the losses.
The study found that groundwater storage in the Lower Basin is especially vulnerable because natural recharge is limited. Researchers examining Arizona’s Active Management Areas found that groundwater declines were linked largely to increased pumping during drought and reductions in Colorado River supplies.
The study also concluded that groundwater losses across the Colorado River Basin have exceeded losses from the system’s major surface reservoirs.
That finding is significant because groundwater is often treated as a backup when surface water supplies decline. If both systems are losing water at the same time, communities have fewer options during extended drought.
October storms did provide some short-term relief.
Arizona’s Family reported that Lake Powell gained about 12 feet in two weeks following recent storms. Despite the increase, the reservoir remained at approximately 25% capacity. Lake Mead remained even lower, at about 23% capacity.
Water experts cautioned that rain in Arizona and other desert areas does not replace the Rocky Mountain snowpack that supplies most Colorado River runoff.
More than 80% of the river’s flow originates from snowpack in the Upper Basin, making the upcoming winter an important factor in determining reservoir conditions next year.
Together, the final week of October showed how several pressures are building at the same time. Arizona and CAP are challenging the federal shortage framework in court. Tribal Nations are seeking congressional approval for long-standing water rights and infrastructure. Groundwater reserves are declining alongside surface supplies. And temporary storm relief has not changed the long-term condition of Lake Powell and Lake Mead.
What does this mean for CRIT?
The CAP lawsuit is relevant to CRIT because it could influence how federal Colorado River rules are interpreted and how future shortages are divided between the Upper and Lower basins.
CRIT’s senior rights place the Tribe in a different legal position from CAP, which holds a much more junior priority. However, court decisions affecting reservoir operations, interstate obligations, and federal authority can still shape the larger system where CRIT exercises its rights.
The northeastern Arizona settlement is also important from a Tribal water perspective. It demonstrates again that water rights are only part of the issue. Tribal Nations also need infrastructure, funding, and legal certainty to put those rights to use.
For CRIT, that distinction is especially relevant because the Tribe already holds senior, quantified Colorado River rights and has extensive agricultural use of those supplies.
The groundwater study adds another concern. As cities and other water users turn toward groundwater to compensate for reduced Colorado River deliveries, Basin-wide groundwater losses show that it cannot be treated as an unlimited replacement supply.
Finally, the recent rise at Lake Powell is welcome, but it does not represent a recovery of the Colorado River system. Reservoir levels remain low, and the amount of snow that falls in the Upper Basin this winter will play a much larger role in determining future river conditions.
For CRIT, the week reinforces the importance of protecting senior rights while continuing to monitor federal operations, Tribal water settlements, groundwater conditions, and the physical health of the Colorado River itself.
Sources
KJZZ: “Central Arizona Project moves to join Colorado River water lawsuit against the federal government”
https://www.kjzz.org/politics/2026-10-27/central-arizona-project-moves-to-join-colorado-river-water-lawsuit-against-the-federal-government
ABC15 Arizona: “Interior secretary warns Arizona over Colorado River lawsuit”
https://www.abc15.com/news/local-news/interior-secretary-warns-arizona-over-colorado-river-lawsuit
Arizona Capitol Times: “Water settlement would be game-changer for northeastern Arizona tribes, experts argue”
https://azcapitoltimes.com/news/2026/10/28/water-settlement-would-be-game-changer-for-northeastern-arizona-tribes-experts-argue/
University of Arizona Water Resources Research Center: “Study Charts Drought Impacts on CRB Groundwater”
https://wrrc.arizona.edu/news/study-charts-drought-impacts-crb-groundwater
Arizona’s Family: “Recent storms boost Arizona reservoir levels, but Colorado River crisis persists”
https://www.azfamily.com/2026/10/30/recent-storms-boost-arizona-reservoir-levels-colorado-river-crisis-persists/