PHOENIX—The nation’s fifth-largest city and surrounding metropolitan area is officially tapped out of groundwater, Arizona Gov. Katie Hobbs announced Thursday, adding another item to the state’s long list of water woes.

By 2121, the Phoenix metro area will be short of nearly 5 million acre feet of water—enough water for around 17 million homes—under a new groundwater model released Thursday by the Arizona Department of Water Resources. 

That means any new development in the region that hasn’t had its water guaranteed will have to rely on another source of water, such as the Colorado River and other local rivers, or on yet-to-be developed sources like desalinated ocean water, recycled wastewater or groundwater pumped from other basins in the state, to ensure existing homes and developments have the water they need in the future. 

Since 1957, Arizona’s population has surged 555 percent while water usage has decreased 3 percent. Much of the state’s growth has come in the form of sprawling suburbs built on cheap land in the desert, which often relies solely on groundwater. 

Sarah Porter, the director of Arizona State University’s Kyl Center for Water Policy, said Thursday’s announcement means developers will now have to weigh the cost of building on more expensive land that has an assured water supply, or find new water sources on land that can no longer rely on groundwater, as climate change produces intensifying droughts.

State officials cautioned the model shows the state’s groundwater laws are working and that Arizona’s water supply is secure and would only largely impact certain areas in the region. 

When Arizona passed its Groundwater Management Act in 1980, the state decided it would keep track of groundwater in the most populated parts of the state, Porter said. With the modeling showing the Phoenix metro area is not adequately replenishing the groundwater it is taking out of its aquifer, the state is stopping growth on that finite resource.

“The regulations are working to prevent homes from being sold and then having no water,” Porter said. 

The cause of the unmet demand, officials said, is decades of overdrafting groundwater in the region and heavy reliance on the resource as the area has grown. Hobbs also announced $40 million in funding from the COVID-19 stimulus act passed in 2021 to be administered by the Arizona Department of Water Resources for water conservation, new water infrastructure and efforts to promote sustainable groundwater use throughout the state. The money comes on top of millions of dollars in additional funding announced last year for conservation and efficiency efforts.

Water issues are nothing new in Arizona. 

Its share of the Colorado River has been cut nearly 25 percent in recent years, with even further reductions on the horizon, forcing the state and its cities to limit water use and search for new supplies. 

On the outskirts of the Phoenix metro area, cities like Buckeye have been forced to spend millions finding new sources of water after the state water department found the area didn’t have enough groundwater for all the development planned in the region. A community on unincorporated county land outside of Scottsdale had its main water supply cutoff at the start of the year as part of the city’s drought management plan.

Outside of Arizona’s major metropolitan areas, groundwater remains largely unregulated and used for water intensive agriculture. 

Under Hobbs, a Democrat who took office in January, the state has made a string of major announcements regarding water in the state. 

Hobbs quickly released a similar report that had been withheld for years that found that a portion of the West Valley outside of Phoenix could no longer grow on just groundwater and would need to find new resources to receive assured water certificates from the state. 

Last month she announced the members of the newly formed Governor’s Water Policy Council, which will help modernize the state’s existing groundwater law. The state also reached a voluntary agreement with California and Nevada to cut back its use of Colorado River water until 2026 to help preserve the nation’s largest reservoirs and respective dams from reaching a point where electricity can no longer be generated or where the river no longer flows past them. 

“We are not out of water and we will not be running out of water,” Hobbs said.

That’s largely true for cities like Phoenix, which have a robust water portfolio, with secure water rights from the Colorado River and the Salt River Project, a state utility that provides water from the Salt and Verde Rivers and from 250 groundwater wells. Arizona law requires developers in the most populated parts of the state to obtain a certificate from the Department of Water Resources ensuring adequate water supply for 100 years and major water providers with those certificates will not be impacted. 

But a reckoning is coming for fast-growing communities on the outskirts of the Phoenix metro area that have largely grown on groundwater and have few other existing resources to tap into.

New sources are proving costly for communities like Buckeye and Queen Creek, which have seen huge surges in population in recent years and expect to grow even more in the coming decades.

In January, Buckeye spent $80 million for just under 6,000 acre feet, a small amount given what the new groundwater model shows the region needs to find—and the amount of future growth the city is anticipating. 

It also means subdivisions outside of a water provider’s service area can no longer rely on the water beneath them. 

The announcement won’t stop growth in the region, but water policy experts have long cautioned that the state’s recent growth rate  may no longer be sustainable, meaning outward sprawl into the desert won’t remain a viable option.

“It’s not about stopping growth,” said Haley Paul, Arizona policy director for the National Audubon Society. “It’s about where and how we grow.”