Phoenix spent decades storing water underground and hundreds of millions of dollars building pipelines, wells and treatment systems for a future in which the Colorado River could no longer supply all the water the city had come to expect.
That future is getting closer.
A sweeping federal decision issued Friday will substantially reduce Arizona’s Colorado River supply beginning next year, and Phoenix says it is preparing to operate its water system differently — potentially drawing more heavily on stored water and other backup supplies while accelerating development of new sources.
But the decision by the U.S. Department of the Interior and Bureau of Reclamation did not settle the much larger fight over the river’s future.
Instead, after years of negotiations failed to produce agreement among the seven Colorado River Basin states, Interior established firm operating rules for 2027 and 2028 and a broader framework under which it expects to make additional decisions through 2036.
For Arizona, the immediate numbers are substantial.
The new Bureau of Reclamation guidelines require Arizona, California and Nevada — the three Lower Basin states — to take a combined 1.25 million acre-feet reduction in Colorado River deliveries in both 2027 and 2028.
Under a proposed sharing agreement developed by the three states and incorporated into the federal guidelines, Arizona would absorb 760,000 acre-feet of that annual reduction. California would give up 440,000 acre-feet and Nevada 50,000.
The Lower Basin states also are expected to voluntarily conserve and store at least another 700,000 acre-feet during the two-year period.
An acre-foot is about 326,000 gallons, roughly enough to supply three average households for a year.
For Phoenix, where approximately 40% of the drinking-water supply comes from the Colorado River through the Central Arizona Project, the decision does not mean customers are about to find their taps running dry.
Nor does it immediately impose mandatory water-use restrictions.
But city officials said it means Phoenix must begin preparing for significantly less Colorado River water.
“The federal government’s decision does not provide the fair, basin-wide leadership the Colorado River crisis demands,” Mayor Kate Gallego said Friday after the Interior Department released its decision.
“Though Phoenix is prepared for this moment because of decades of planning and conservation,” she continued, “we will push for new federal support to mitigate the rising cost of water that will result from this federal decision.”
Noting “Phoenix has prepared extensively for reduced Colorado River supplies, and our customers can continue to expect reliable water service,” Phoenix Water Services Director Brandy Kelso warned:
“But preparation does not mean we can be complacent. Balancing supply and demand will require us to carefully manage our reserves, invest in future supplies, and work with residents and businesses to use water as efficiently as possible.”
Phoenix’s preparations include water stored underground for future shortages, groundwater-recovery infrastructure, the Drought Pipeline that allows Salt and Verde River water to be moved to north Phoenix, conservation investments, and the development of Pure Water Phoenix and other future renewable supplies.
“The water we stored underground was developed for conditions like these,” Phoenix Water Resources Management Advisor Dr. Max Wilson said in the wake of the federal decision .
“Those reserves provide a critical bridge, but that bridge must lead to the next generation of renewable water supplies. Phoenix will use this moment to accelerate the projects and partnerships needed to strengthen reliability for decades to come.”
The federal action comes amid conditions that have moved well beyond the drought scenarios envisioned when many of the rules governing the Colorado River were written.
Lake Powell and Lake Mead combined now contain less water than at any time since before Powell began filling following completion of Glen Canyon Dam in 1963, according to the Bureau of Reclamation.
Both reservoirs reached record-low elevations in August, the result of a record-low snowpack that only exacerbated a 26-year drought in the Colorado River Basin.
Federal officials increasingly are concerned about keeping Powell and Mead high enough to protect the dams and other infrastructure that control and deliver the river.
The new rules call for Lake Powell releases to be adjusted according to actual hydrology with the objective of keeping the reservoir at or above elevation 3,510 feet to support reliable operation of Glen Canyon Dam. Last week, Lake Powell’s level was listed as only 149 feet above Deadpool and less than 22% filled.
A two-year answer
The federal government adopted what it calls a “Decision Framework” running from 2027 through 2036.
That framework establishes operating principles, reservoir thresholds and upper and lower limits within which future operating rules can be written.
The actual operating guidelines adopted last week cover only 2027 and 2028.
Interior has not determined how much water Arizona or Phoenix will receive every year through 2036.
The structure deliberately leaves room for negotiations among the Basin states, tribes and other water users to continue.
The Bureau acknowledged Friday that consensus on long-term operations “did not materialize.”
Arizona officials characterized the immediate agreement more favorably than Phoenix.
Arizona Department of Water Resources Director Tom Buschatzke called the two-year outcome a short-term victory because it avoided substantially larger reductions the federal government had been considering.
The broader federal framework allows considerably deeper Lower Basin cuts if reservoir conditions continue deteriorating.
But Arizona has not abandoned its objections to how future shortages might be divided.
Buschatzke said Friday that the state continues to reserve its legal options as negotiations proceed.
Arizona, California and Nevada themselves proposed the 1.25 million-acre-foot Lower Basin reduction in May as a bridge while the seven Basin states continued negotiating.
The proposal was intended in part to avoid an immediate federal decision imposing even greater reductions while buying additional time to reach a Basin-wide agreement.
Phoenix supported the collaboration among the three Lower Basin states and specifically thanked California and Nevada for sharing the near-term reduction.
Its criticism is aimed more broadly at what it regards as an imbalance between the Lower and Upper basins since there are no reductions in supply for Colorado, Wyoming, Utah and New Mexico.
Lower Basin interests have argued that declining river flows require measurable reductions throughout the Basin while Upper Basin representatives have countered that their states already live with variable water supplies because much of their use depends directly on annual snowpack and runoff.
The legal framework governing the Upper and Lower basins also differs, limiting Interior’s ability simply to impose identical reductions everywhere.
Phoenix nevertheless said Friday that the federal approach “places a disproportionate share of the responsibility for balancing the Colorado River on Arizona and other Lower Basin states without requiring sufficient action throughout the Colorado River Basin.”
The city said a lasting agreement must spread responsibility across the Basin, account for current hydrology, protect critical reservoir elevations and recognize conservation and water-storage investments already made by cities, tribes and agricultural users.
One number is not yet known:
How much of Arizona’s 760,000-acre-foot reduction ultimately will come from Phoenix.
City officials said they are still evaluating how the reductions will be implemented through the Central Arizona Project and what they will mean for Phoenix’s individual Colorado River supplies.
That matters because Arizona’s statewide reduction cannot simply be applied proportionately to every CAP customer.
Colorado River rights in Arizona are governed by a complicated hierarchy of priorities, contracts and entitlements.
Phoenix also historically has not used all of the Colorado River water to which it is entitled.
Approximately 40% of the city’s current drinking-water supply comes from the Colorado River, while about 58% comes from the Salt and Verde rivers and roughly 2% from groundwater.
Whatever the eventual impact on Phoenix, city officials say they have multiple layers of protection before reduced Colorado River deliveries become reduced water service to customers.
One of Phoenix’s largest defenses is underground. Over decades, the city has stored approximately 700,000 acre-feet of water underground for future shortages.
Phoenix has approximately 20 groundwater recovery wells capable of accessing stored and other groundwater supplies and expects to add about 10 more over the next several years.
City officials now say they are prepared to increase use of that stored water and other backup supplies if necessary.
Wilson stressed that the reserves are not a permanent substitute for the Colorado River.
“Those reserves provide a critical bridge, but that bridge must lead to the next generation of renewable water supplies,” he said.
Stored water allows the city to absorb shortages while new supplies are developed. Continually pumping those reserves without replacing them would merely postpone the problem.
Phoenix also has completed one of the biggest pieces of infrastructure in its shortage strategy.
The roughly $300 million Drought Pipeline allows water from the Salt and Verde river system to be moved into portions of north Phoenix that historically have depended more heavily on Colorado River water.
Phoenix also has agreements and infrastructure intended to provide additional flexibility with Tucson and the Salt River Project during Colorado River shortages.
Together, the stored water, recovery wells, Drought Pipeline and regional arrangements give Phoenix options that did not exist during earlier periods of Colorado River development.
The city’s longer-term strategy increasingly involves developing supplies that do not depend on the Colorado River.
Pure Water Phoenix eventually is expected to produce more than 50,000 acre-feet of drinking water annually by using advanced treatment technology to purify wastewater.
Phoenix already secured $179 million in federal funding for the planned North Gateway Advanced Water Purification Facility.
The city also is pursuing expansion of Bartlett Reservoir to increase storage on the Verde River and working with Tucson on the Secure Water Arizona Program, a system of water-sharing and infrastructure arrangements intended to improve both cities’ ability to withstand Colorado River shortages.
Gallego said Phoenix will seek additional federal assistance to offset the higher costs of securing and developing replacement supplies.
In April, Interior Secretary Doug Burgum asked the seven Basin states to identify potential water-supply and conservation projects.
The department said Friday it continues reviewing those proposals and will work with states and tribes to identify opportunities for federal cost-sharing involving water storage, infrastructure expansion, desalination, advanced water treatment, water exchanges and other projects.
The city has not publicly detailed how much additional federal money it intends to seek or precisely which projects it will ask Washington to support.
Another unresolved issue predates Friday’s decision: the role of the Colorado River Basin’s 30 federally recognized tribes.
Tribes hold substantial rights to Colorado River water, including some of the most senior rights in the system.
During development of the post-2026 rules, tribal leaders repeatedly argued that consultation with the federal government was not the same thing as having a direct role in negotiations over how the river would be managed.
Those concerns continued in the weeks leading to Friday’s final action.
The Colorado River Indian Tribes, whose reservation stretches along the Arizona-California border, called for Interior to delay its final decision while raising concerns about tribal participation.
CRIT also successfully opposed a potential approach that could have imposed proportional cuts across water users regardless of existing priority, an outcome important to tribes holding senior rights.
Interior, for its part, says it engaged extensively with tribes throughout the three-year environmental-review process and said Friday that concepts submitted by Basin tribes were incorporated into the new guidelines.