Groundwater levels declining in cities despite rules
While groundwater is rapidly falling in rural farming communities across Arizona, Phoenix, Tucson and other cities haven’t reached that desperate situation.
That’s because in the urban areas of the state — where there are rules limiting groundwater pumping — underground water levels have stabilized or risen in many areas in the past four decades.
But there’s a catch: Water levels have risen in large part because of water imported from the Colorado River, which supplies cities and is also put into the ground to recharge groundwater. Water levels in some of the wells surrounding these recharge sites have jumped 150 to 200 feet since the early 1980s.
Starting next year, though, there will be much less of that river water available to prop up aquifers. Those cutbacks combined with weaknesses in regulations mean the water picture in Arizona’s urban core is not as secure as once thought.
Overall, the average water levels
measured in wells across all of the state’s “active management areas” in central Arizona have risen slightly since 1980. By contrast, average water levels in unregulated rural areas are threatening to surpass all-time lows reached in the mid-1980s.
But not every basin in active management areas — often referred to as AMAs — has seen gains. In more than half of the sub-basins in managed areas, average water levels have declined since the 1980s even with additional imported water and restrictions on groundwater pumping.
Average water levels have fallen more than 20 feet from the early 1980s to recent years in the northern Phoenix area, including the Carefree, Lake Pleasant and Fountain Hills sub-basins. Average water levels also dropped that much in managed areas covering west Phoenix and Tucson.
Overall, three of the five AMAs were down on average when comparing levels from the 1980s to levels in the last 10 years. Two of them were down fractionally, while the Phoenix and Pinal AMA averages increased.
For individual wells, 53 percent of wells inside AMAs increased when comparing the average water level in the past five years to averages from 19801985. In unregulated areas, only 30 percent of wells had higher water levels.
The Colorado River is under increasing pressures due to years of overuse and drought, compounded by the effects of climate change. Next near, Arizona will face its first mandatory cutbacks in Colorado River water under a deal that aims to keep enough water in Lake Mead to avert a crash.
The cuts will place greater strains on Arizona’s groundwater supplies by promoting more pumping in some areas, such as the farmlands of Pinal County, and by eliminating much of the water that’s available for replenishing aquifers.
Chuck Cullom, manager of Colorado River programs for the Central Arizona Project, has said the reductions will mean “eliminating the water that would have been available for underground storage, banking and replenishment.”
In 1980, Arizona became the first state in the nation to pass a comprehensive groundwater management law. It imposed limits on pumping and added new rules in urban areas intended to ensure long-term water supplies.
Even though the 1980 law set a goal of reaching “safe yield” in each AMA by 2025 — a long-term balance between the water that’s pumped out and the amount going back into aquifers — the latest data show that the managed areas are either not on track to achieve this target or struggling to get there.
Cracks are showing in the regulations inside AMAs as well. A recent Arizona State University report said there likely won’t be enough water available from the Central Arizona Project in the long term to replenish the groundwater used by all of the homes that are being planned.
Giant new subdivisions have been built in outlying suburbs that rely entirely on groundwater. In many cases, they’re located dozens of miles away from water being recharged to provide the “assured water supply” that allowed the homes to be built.
So much water is being pumped for development in some areas that cities and developers are looking at ways of importing water from rural Arizona.
“It’s certainly going better than it would have been without the groundwater management act,” said Kathleen Ferris, a former state water director who helped draft the 1980 law. “I can’t even imagine what the Phoenix area and the Tucson area and the Prescott area would have been like without the groundwater management act. It’s really hard for me to even think about it. It would have been pretty dire.”
But Ferris said much more needs to be done to ensure there’s enough water in the future for managed areas.
“We’re not going to achieve a balance between pumping and withdrawals,” Ferris said. “We’re coming into a drier future. We’re already into it.”
The rules or the water?
Arizona’s use of groundwater changed dramatically after the completion of the 336-mile CAP Canal, which carries water from Lake Havasu across the desert to Phoenix, the farmlands of Pinal County and Tucson.
The $4 billion project, mostly completed in the 1980s, brought central Arizona supplies to feed urban growth, and enabled cities and farms to pump less groundwater.
Tommy Hoover, a third generation well-driller, said construction of the CAP canal almost put his dad out of business and caused him to struggle for years. But the threat of CAP water being curtailed has breathed energy into his business.
When he’s drilling in rural Arizona, where there are no regulations, the groundwater level is dropping, he said. When he drills inside managed areas, he sees the water levels steady or rising over time. He attributes that to the arrival of CAP water.
“It’s the simple fact that they have CAP water and they’ve not been having to pump,” said Hoover, owner of Hoover Drilling Co. “When CAP water is gone, we’ll have to go back to old wells.”
Ferris said the combination of imported Colorado River water and regulation of groundwater pumping has helped stabilize aquifers in managed areas. Those rules included requiring a 100-year assured water supply to build houses, moving big cities toward the use of renewable water resources and efforts to “bank” unused CAP water and treated wastewater underground.
Katharine Jacobs, a professor at the University of Arizona and director of the Center for Climate Adaptation Science and Solutions, said changes in managed areas, such as requirements for metering wells and filing annual reports, have also made a difference.
But the biggest change, Jacobs said, has occurred through the focus on using Colorado River water to stem groundwater overdraft in managed areas. Unregulated areas never had that.
“Essentially, the places that are regulated are definitely doing better than the places that aren’t,” she said.
More houses than water
The state’s groundwater law requires that new housing subdivisions in regulated areas need to show an “assured water supply” will be available for 100 years in order to be built.
In practice, this concept has proven slippery and evolved in a way that has cleared the way for rapid growth, even as concerns have emerged that in some areas water supplies may be insufficient in the long run.
Rules adopted by the Legislature in 1995 allowed developers to get certificates of assured water supplies by relying on groundwater, provided that the groundwater would be replenished with surface water obtained subsequently by the Central Arizona Groundwater Replenishment District.
In a report released in October, Ferris and fellow ASU researcher Sarah Porter, who leads the Kyl Center for Water Policy, detailed how the district has been riddled with a host of problems as enrollment of new subdivisions has grown far beyond expectations, creating “serious challenges for prudent water management.”
They said a key assumption — that there would be sufficient CAP water to meet replenishment obligations through 2046 — proved incorrect “as enrollment radically outpaced this supply and other entities with long-term CAP contracts used more and more of their rights.”
Impending cuts in deliveries of Colorado River water will further reduce the amount of CAP water that’s available for replenishment, the report said. With competition for water on the rise, they said the district will have a harder time acquiring additional supplies to replenish groundwater.
“This grim reality leads to a crucial question: Who will provide water to homeowners and businesses ... if their wells run dry?” they asked.
The recharge district is not required to replenish the water where its members pump it, which means there is a huge disconnect between where the water is pumped for houses and where the replacement water is located, Ferris said.
“We could have a situation where we have lots of development on lands that really don’t have access to a real secure water supply down the road,” she said.
State water officials released new studies in October on the Pinal AMA, saying that looking out 100 years, there isn’t sufficient groundwater for the existing water uses and the projected needs of planned subdivisions.
The researchers said a similar problem could emerge west of Phoenix, where state officials have issued and extended several initial water analyses for large master-planned communities. They cited Buckeye, which depends entirely on groundwater and is planning to more than triple in size by 2040. They also noted that according to one projection, the population of the West Valley could grow to more than 2 million by 2050.
Available water for new growth and development is already scarce enough within AMAs that urban areas have looked to get water from unregulated rural Arizona, which is in the midst of a water crisis.
Recently, these efforts have been met with opposition. A proposal for a 25year lease of water from the town of Quartzsite was rejected, as was a proposed deal in which the Central Arizona Project considered buying farmland in Mohave County to use the rights to Colorado River water.
But the urban water suppliers have been looking to rural areas to supply water for new subdivisions for a long time. That’s why loopholes were written into the law that would allow for piping in water from places like McMullen and Harquahala valleys in western Arizona.
No ‘safe yield’ in sight
Paul Hirt, a professor and environmental historian at Arizona State University, has been critical of Arizona’s approach to groundwater. In a 2017 article on water consumption and sustainability, Hirt and other researchers wrote that “the structural deficit in Arizona’s water supply has been partially masked by unsustainable pumping of groundwater.”
“Arizona continues to extract far more water from its ancient aquifers than is recharged, despite more than three decades of concerted effort to reduce groundwater overdraft beginning with the passage of the Arizona Groundwater Management Act in 1980,” the researchers wrote. “The act mandated that Arizona’s major municipal and agricultural regions achieve ‘safe yield’ of groundwater by 2025, yet hardly anyone expects this goal will be met.”
Ferris said it’s clear from the latest state reports that the Phoenix AMA isn’t on track to achieve safe yield by 2025.
Arizona has more experience than most states with using surface water to replenish groundwater. State figures show Arizona has banked about 11 million acre-feet of surface water in aquifers since the mid-1990s. An acre-foot is enough water to supply three average Phoenix households for a year.
But Hirt and his co-authors pointed out that annual consumption in Arizona from all sources ranges from 7 million to 9 million acre-feet.
“So, 20 years of storage effort resulted in a little over a year of stored water,” the researchers wrote.
In 1996, the Central Arizona Project started sending Colorado River water to groundwater replenishment ponds to boost aquifer levels. Water poured into ponds that were carved into the permeable desert soil in places along the CAP Canal, from Tonopah to the Pima Mine Road recharge facility south of Tucson.
In the areas surrounding more than 10 recharge sites, groundwater levels have risen with water pouring in over two decades, The Arizona Republic found.
“If you look carefully at the geography of those areas where the water has come up, it’s almost invariably in places where CAP water is available or where water banking is taking place,” Hirt said.
Hirt said even with the years of banking water underground, “it’s going to come back out as soon as we start having shortages again.”
Managed areas of the state are doing better than rural areas without regulation, but AMAs still face major challenges.
“Outside the AMAs, there is almost no progress at all and things are getting much worse,” he said. “In areas within the AMAs, there’s been limited progress. It’s not enough, and it’s qualified progress, and it’s probably not going to be sustained much longer.”
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.