June 2, 2025

Arizona Colorado River Update

Last year the Kyl Center for Water Policy introduced a new blog series featuring updates on Colorado River, groundwater and other water policy issues in Arizona.

The next two years will be pivotal as stakeholders negotiate the reservoir operating rules that dictate Colorado River shortages in our state, and these shortages will impact our groundwater. We will try to bring some clarity through light-hearted updates featuring a movie theme. This is our fourth segment in this series. We hope you enjoy it!

Sadly, this is not a picture of a volcano but rather the Western Slope of Colorado. From the Bureau’s May 2025 24-month study: “The May 2025 unregulated inflow forecast for Lake Powell is 1.10 maf or 53% of the 30-year average. The 2025 April through July unregulated inflow forecast for Lake Powell is 3.50 maf or 55% of average. The [Water Year] 2025 unregulated inflow forecast for Lake Powell is 5.91 maf or 62% of average.” Bummer. The May 24-month study projects that Lake Mead will fall to just under 1,060 feet in elevation by January 2026, which if true, means Arizona will remain in Tier 1 shortage. This seems optimistic given Mother Nature’s apparent anger.

Even as lava rather than snow melts off of the Western Slope, according to the latest Bureau estimates Arizona and California combined may use around 200,000 acre-feet more water in 2025  than in 2024. Um, guys?

At the Law of the Colorado River conference in Tucson this April, legal experts noted that litigation can, in fact, lead to agreement because discovery, fact finding and rulings on the law can provide incentives and political cover for compromise. We were reminded that the 1922 compact ultimately came together after another court decision favoring prior appropriation as the rule for the equitable division of interstate water, Wyoming v. Colorado, 259 US 419 (1922). Would litigation subject us to many years of extreme or even intolerable uncertainty?

Why, yes, it would but maybe there’s a bittersweet movie ending ahead. Assuming Arizona and Colorado are the dad and mom, we think Nevada might play a pretty good, dour Drew Barrymore.

Divorce be damned! Our brave negotiators are all still working diligently to come up with a Hail Mary, and the feds are fully engaged. According to the grapevine, the seven-state principals are continuing to meet on a near-constant basis and have even come up with some creative ideas we’re not sure we’re allowed to mention, so naturally we’ll just go with the flow and not say a peep. We’re down to the last play in the fourth quarter, the quarterback is hurt, the receiver is running around in weird circles, the running back has disappeared into the transfer portal and it’s too painful to watch, but miracles can and do happen so let’s all hope this is one of those plays.

In the same 1944 treaty in which the U.S. owes Mexico 1.5 million acre-feet each year from the Colorado River, Mexico owes the U.S. 1.75 million acre-feet every five years from the Rio Grande River. People who know are saying it will be impossible for Mexico to meet its treaty obligations on the Rio Grande in October when its five-year requirement is tallied. Recently, the U.S. fired a warning shot across the bow by refusing to deliver Colorado River water to Tijuana via a “special delivery channel” (which means sending Mexico’s water to Tijuana from Lake Havasu via an aqueduct in Southern California rather than from Morelos Dam via the Alamo Canal), but the big question is what comes next? Will the U.S. refuse deliveries to Mexico on the Colorado side in an amount equal to Mexico’s deficit and use it to prop up Lake Mead instead? Colorado River negotiations are bound up with the Rio Grande conflict, greatly complicating things. When it comes to binational water sharing agreements, water is susceptible to becoming one more negotiating point in a much larger scheme. We don’t know what comes next, but we have a hard time believing the answer is “nothing.”

This is a beautiful image, but we all know beauty can be illusory. In a world of differing views of the impacts of the Colorado Compact, either dreams of growth are shattered, or life as we know it becomes a distant dream. Perhaps the basis of a compromise is the development of “Floating Pools.” This is water in Lakes Mead and Powell that is intentionally held separate from the prior appropriation system and is operationally neutral, meaning that it doesn’t count in determining reservoir levels. In the Kyl Center’s new paper, we explain that this beautiful dream is possible, but only if the water in the Floating Pools meets three conditions: it actually makes its way to Lake Powell, it has a history of consumptive use, and it is assessed realistic evaporative losses. Otherwise, the beautiful dream might be a painful illusion, especially for central Arizona.

• Read our explainers on the Yavapai-Apache Indian Water Rights Settlement and the Northeastern Arizona Indian Water Rights Settlement.
• Explore our paper Enduring Solutions on the Colorado River.
• Try our Colorado River Story Map, that explains all things shortage in Arizona.
• Read our paper on Colorado River Shortage Impacts to Tap Water Deliveries in Central Arizona, that details where major water providers get their tap water and how they will continue to meet tap water needs under shortage conditions.
• Our Shortage Impact Calculators might also be helpful.