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How will Arizona deal with Colorado River shortages? Cities need a 'Plan B,' expert says
BOULDER, Colo. — Kathryn Sorensen likes to compare the options for finding water rights in central Arizona with shopping for clothes. Some options, such as tearing out turf, are like thrifting: cheap but a little picked over. Others, like desalination, are like buying a tiny designer handbag, expensive and ultimately limited in its capacity. And then there are other options, which might involve buying or borrowing other people's clothes, and those options involve politics.
Sorensen, director of Arizona State University's Kyl Center for Water Policy, spoke June 5 to an audience of water managers, scientists and tribal leaders at the 45th annual Colorado Law Conference on Natural Resources in Boulder, Colorado. She laid out how cities and developers are struggling for more limited water resources in the area of the Colorado River Basin most vulnerable to water cuts: central Arizona.
'If cuts become deep enough, and there's clearly a chance that will happen, I want to say in no uncertain terms, I am extraordinarily concerned that we will hit critical levels,' Sorensen said in an interview. 'There are cities that rely on that (water) directly, and we need to make sure that those cities have a Plan B.'
The Colorado River, which provides 40% of water for Phoenix, along with most of Arizona's largest cities, is experiencing low flows unprecedented in U.S. history. The federal government declared the first official shortage on the river in 2021. Maricopa, Pima and Pinal counties were the first to take serious cuts under an agreement struck decades ago to secure support for the Central Arizona Project Canal.
So far, those cuts have dried up farms in Pinal County, but most cities and tribes have stayed wet, in part because the Gila River Indian Community volunteered to conserve some of its water in Lake Mead.
That arrangement does not guarantee water after 2025, and the Colorado River Basin states are stalled in negotiations to define guidelines for how to manage shortage on a larger scale after 2026.
A drier future: Worsening climate outlooks raise the stakes for an agreement on the Colorado River
In the long term, scientists expect climate change to continue drying the river basin, leading to low flows. Just this year, flows into Lake Powell, used to measure the river's natural water supply, are expected to be roughly half of normal, and even that 'normal' is lower than it once was in the 20th century.
'Our current climate trajectory is beyond awful,' said Brad Udall, a water and climate research scientist at Colorado State University, speaking at the same event on June 5.
As new water-using developments and industries move into the Phoenix area, water managers are examining their options for how to avoid sharp consequences, Sorensen said. Cities like Buckeye could lose the majority of their Colorado River water.
Some cities have immediate back-ups to fill holes left by Colorado River shortages. Phoenix has spent hundreds of thousands of dollars on a pipeline to bring water from the Salt and Verde rivers to parts of the city that rely entirely on the Colorado. Tucson can rely on groundwater in the short term to cover its losses, but those aquifers are limited in the long run and don't provide a lasting, sustainable solution. Sorensen worries about municipalities that don't have those kinds of options.
Water users in central Arizona are competing to find supplies that can provide them with assured water for a hundred years, a requirement in Arizona law, given diminished deliveries from the Colorado River, Sorensen said, and cities and developers are constantly scrambling to get entitlements to water to meet that requirement.
The first and cheapest option in stretching water supplies is conservation, Sorensen said. Since 1978, the portion of Phoenix single-family homes that use lush landscaping like lawns has plummeted from nearly 80% to around 20%, a result of intentionally increased water rates. Nonetheless, Sorensen said cities have already conserved a lot of water, and conserving more may see diminishing returns.
The next-easiest option is for cities to lease water from other entities in central Arizona. The Phoenix area hosts a busy informal market for water leases, where entities with water rent out it out to those in need. The Salt River Pima–Maricopa Indian Community, for instance, leased out all of its Colorado River water in 2021.
By contrast, Chandler leased half of its Colorado River water from other parties in that year, according to the Kyl Center (leases are not inherently more vulnerable to cuts in the short term, but need to be renewed or replaced in the long term). But, as Sorensen pointed out, leasing depends on how willing an entity, usually a tribe, is to lend its water for a long time.
'They are sovereign nations," she said. "It is their choice.'
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Cities and other water users can also rely on long-term storage credits, meaning they get to pump groundwater that other entities have saved underground. That option is a favorite for data centers, Sorensen said, which sometimes must purchase some of their own water supplies instead of relying on municipalities. Still, that option is usually a 'last resort,' Sorensen said, as the water is nonrenewable, so once entities pump it they need to go out and find another long-term water source.
All of these options involve shuffling the amount of Colorado River water already being delivered to the Phoenix and Tucson areas, but what about other sources? Cities in central Arizona are looking there too. A coalition of local governments is looking to build new storage on the Salt and Verde rivers, which could bring more water to the Phoenix area, but that project may not be completed until 2040.
There is one option that may not require any infrastructure and could provide access to a massive chunk of Arizona's Colorado River water: leasing or buying agricultural water from the farms in the Colorado River Valley in the western part of the state. Together, the tribes of the Colorado River Valley and farmers in Yuma County hold rights to hundreds of thousands of acre feet of water that, unlike central Arizona's current water supply, is much safer from water cuts administered by the federal government.
The idea is controversial, politically fraught, and potentially so lucrative that it has drawn the attention of private equity firms.
'You see private equity purchasing farms for the purchase of selling that water,' Sorensen said.
Only one of these transfers has occurred to date, in which a private equity firm called Greenstone bought farmland in La Paz County and sold the farms' water entitlements to Queen Creek for $24 million in 2023. Local officials in western Arizona fumed about the sale, which dried almost 500 acres of farmland, worrying that it would lead to weaker local agricultural communities.
Since then, the Colorado River Indian Tribes, which hold Arizona's largest and highest-priority Colorado River entitlements, have received congressional approval to lease some of their water to off-reservation users, though they haven't moved to do so.
Rural shortages: It's not just big alfalfa farms. La Paz residents fear groundwater grab by big cities
In a May interview, CAP board president Terry Goddard said he had recently visited Yuma and wanted to open discussions about farmers there sharing water with central Arizona users. Goddard said cuts in central Arizona were getting down to the bone, and it was unacceptable to dry out the tribes and critical industries in the state's most populous region. So far, he said those discussions haven't happened.
Presenting a slide titled, 'The future of Ag to Urban Transfers,' Sorensen wondered aloud whether those arrangements would happen in the future, calling them a 'big maybe.'
Farms account for at least three quarters of human water consumption in the lower Colorado River Basin, according to Brian Richter, a researcher and president of Sustainable Water. As cities look to sustain themselves on a diminishing piece of the Colorado River, Phoenix-based water consultant and attorney Peter Culp said in another presentation, conversations about the river often pit the two sectors against one another.
Culp runs a nonprofit bank, Blue Commons, that provides low-interest loans to farmers and tribes to build water conservation infrastructure. The bank is designed to give farmers an alternative to selling their farms to private equity firms like Greenstone by making farming more financially feasible and providing financing that doesn't ultimately lead back to Wall Street investors.
Having grown up in a farming community, Culp said he sees the transfer of water and money from farms to cities as a symptom of a deeper, larger economic shift in the United States and the West.
'We have spent the last hundred years engaged in an extremely effective project of resource extraction and wealth extraction that has systematically moved wealth from the rural parts of this country … into a core,' Culp said. 'Rural America is not doing great, folks.'
Moving forward, Culp said farmers and cities can change their view on ag-to-urban water transfers as an opportunity for mutual benefit. Cities can invest in rural economies, and in return, farmers can conserve water and support cities.
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Though not responding to Culp's remarks, Sorensen viewed the movement in economic activity as more natural.
'People move towards economic opportunity, and some people may wish that were different," she said. "It's not, and it never has been."
Regardless of what happens, Sorensen said in her presentation, water is bound to get more expensive. Sorensen compared Arizona's water to Bitcoin:
'If you didn't buy it already, it's probably too late,' Sorensen said. 'But on the other hand, maybe it's like Bitcoin in that the price just keeps going up and up, and you've got to buy now.'
With values like that, the desalination of brackish groundwater of Pacific Ocean water in neighboring entities — the tiny designer purse in Sorensen's shopping metaphor — could become realistic, Sorensen said.
'The market is tough, especially in the face of Colorado River shortages, so (the tiny purse) might be what we have to turn to,' Sorensen said.
Austin Corona covers environmental issues for The Arizona Republic and azcentral. Send tips or questions to
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This article originally appeared on Arizona Republic: Colorado River cuts push central Arizona to seek water alternatives
