Scottsdale is developing a regional approach to addressing the federal government’s looming supply cuts to Colorado River water.
In a memo to local leaders this week, city management outlined a proposal to trade some of Scottsdale’s advanced purified water — recycled wastewater that’s been treated and drinkable — for a portion of other communities’ water supplies from the Central Arizona Project.
That’s the 336-mile canal system that supplies the river’s water to major Arizona communities.
Under the conceptual plan, which city officials are still evaluating, Scottsdale would pump purified water into the canal system in exchange for other cities or tribes’ water.
Doing so “will strengthen regional supply while also demonstrating a new solution for
drought resilience for years to come,” City Manager Greg Caton and Interim Water Resources Director Thyra Ryden-Diaz stated.
Fascinated by the proposal, water experts from Arizona State University noted that it’s an unprecedented and creative effort that could strengthen the region’s water resiliency.
“The more types of creative exchanges that are available, the better,” said Sarah Porter, director of the Kyl Center for Water Policy within the Morrison Institute for Public Policy. She added that it could give water providers more flexibility to meet demand.
However, she and Cynthia Campbell, the director of policy innovation at the Arizona Water Innovation Initiative at ASU, also questioned whether the proposal makes financial sense for Scottsdale, as it’s already on the cusp of being able to deliver high-quality drinking water directly to its residents.
“It’s not a bad idea,” said Campbell. “It’s just an unusual idea.”
Scottsdale Water spokesperson Bryan Bouchard stressed the plan is far from being finalized as the city still "needs to determine whether the concept is technically, legally and financially feasible, and whether there is interest from potential partners."
The city had not yet formally presented the proposal to the Central Arizona Project as of Sept. 10, Bouchard stated.
A Central Arizona Project spokesperson wasn't immediately available to provide a statement on the concept.
Scottsdale braces for Colorado River cuts
Scottsdale’s proposal comes as Arizona’s allocation from the river will soon fall by roughly 25% over the next two years. That would amount to about 760,000 acre-feet of water, according to the federal plan that’s meant to protect the drought-stricken Lake Mead and Lake Powell.
An acre-foot is roughly equivalent to the amount of water used by three single-family homes in a year, according to the Arizona Department of Water Resources.
The affluent community of Scottsdale relies heavily on the Central Arizona Project, which supplies about 70% of the city’s drinking water — the most of all Valley cities.
It’s still unclear how much Colorado River water Scottsdale will lose under the new federal plan.
By Oct. 1, the city must submit its annual water order to the Central Arizona Project, which will then determine the available supplies and how to distribute the cuts across the communities it serves, Bouchard explained.
While such decisions are expected by mid-November, the Central Arizona Project still wants its communities to request their full allotment for 2027, which for Scottsdale will be 81,271 acre-feet, Bouchard stated.
In 2025, he said, Scottsdale was allotted 81,000 acre-feet of water. The city used about 80% of that and stored much of the rest into aquifers.
Over the years, the city has taken steps to set aside that water for the future and expand its resources. One of its most prominent endeavors to become self-sufficient is its Advanced Water Treatment facility near Loop 101 and Pima Road.
There, the north Scottsdale campus has been purifying recycled wastewater to provide residents with an indirect source of drinking water for about three decades. The city does this, in part, by running effluent water through reverse osmosis membranes and ultraviolet light.
That purified potable water is then recharged into aquifers, pumped out about a decade later for additional purification and then sent to residents’ taps.
Scottsdale’s plan to update the facility so it can deliver that water directly to customers is on hold amid uncertainties over construction costs, new environmental regulations from the state and political hesitancy.
Scottsdale 'reframes' use of purified water
According to the city’s memo, the water department is proposing to continue recharging the aquifers with purified water, as well as discharge some directly into the Central Arizona Project’s canal system.
In return, one or more cities, tribes or industry partners would provide Scottsdale with some of their water supply from the Central Arizona Project.
“As a national leader in advanced water purification, Scottsdale is stepping forward with an innovative approach that reframes how the city can contribute to managing its own water supply and collaborate with regional partners in Arizona,” Caton and Ryden-Diaz stated.
The officials said that the concept is “built around collaboration,” as they would intend to work with the Central Arizona Project, the U.S. Bureau of Reclamation and potential partners to see whether the exchange can benefit all the entities involved.
Scottsdale did not outline any cities or tribes with whom they’re looking to partner.
“Any outreach or discussions with potential partners would be part of the process of determining whether the concept is viable,” Bouchard stated in an email.
If the city can secure any partners, the officials said that Scottsdale would compensate downstream users because there’s still some political pushback surrounding advanced treatment technology and the efficacy of purified water.
It would also help pay for costs directly associated with introducing the purified water into the canal system. That includes water quality monitoring and testing, among other things. The memo did not provide any estimated price tag for the overall concept.
“The goal is simple,” Caton and Ryden-Diaz stated, “put an established Scottsdale water resource to work in a new way, creating value for Scottsdale, strengthening regional partnerships and helping Arizona make the most of every drop.”
Water experts outline pros, cons of concept
Should the Central Arizona Project agree to Scottsdale’s plan, it would be the first time to date that a city would get to discharge water into the canal system, Campbell from the Water Innovation Initiative, explained.
“That’s never been allowed before, mostly because CAP felt compelled to come up with water quality standards to do that,” she said, adding that the agency has been working for nearly a decade to draft those regulations.
Advanced purified water already meets high-quality standards, which would likely meet, it not exceed, any that the Central Arizona Project imposes, Campbell said. And any water that Scottsdale pulls out of the open-air canal must be treated before it gets sent to customers.
That means Scottsdale is “going to pay for water treatment, not once, but twice,” Campbell stressed.
Still, she noted, the plan could make sense for Scottsdale if it doesn’t believe it will be able to deliver purified water directly to customers any time soon.
The Arizona Department of Environmental Quality is still finalizing its revised rules and permitting process for advanced water treatment facilities.
The new rules, department officials previously explained, are meant to focus on chemical and source control, demonstration permits, operator certification and fees, as well as make the water purification program easier to implement without reducing safety standards.
“Until they get that permit from ADEQ,” Campbell said, “then they just kind of have to hold onto the water or put it into the ground.”
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Shawn Raymundo covers Scottsdale and Maricopa County. Reach him at sraymundo@gannett.com or follow him on X @ShawnzyTsunami.
This article originally appeared on Arizona Republic: Scottsdale's 'unusual' plan to help Arizona's water woes | Exclusive
