Think of it as a conversation piece.
That's how a Pima County official, Eric Wieduwilt, describes a new proposal for a $4.1 billion desalination project that would start with a plant to remove salt from seawater in the Sea of Cortez in Sonora, Mexico. Then, the water would be shipped 196 miles by underground pipeline to the Tucson area, says a county study of the project.
The cost could add up to $60 to $90 per month to the typical Tucson-area homeowner's water bill, said the County Regional Wastewater Reclamation Department's study.
The study looks at what it calls a worst-case scenario, assuming an outside water source would be needed if Pima County's population grows nearly 50% by 2100 to 1.5 million and climate change wipes out the Central Arizona Project's water supply from the Colorado River.
"It's theoretical at this point. It’s the idea of, 'If we have to import water where could that water come from?'" said study author Wieduwilt, the wastewater department's deputy director for technical services and engineering. "This is one of many potential options."
He likened this project to the CAP in its scale and its likely time frame for completion. CAP's construction cost was $4 billion in 1993 dollars, and it took its supporters more than four decades to get construction authorized in 1968.
Wieduwilt envisions the desalination project easily taking 20 to 40 years to get approved, financed and built.
"Now is the time to start the conversation of 'what might we have to do,'" he said.
The study has provoked mixed reactions, with environmentalists viewing it warily or very critically. One activist calls it a fantasy. Another views its high costs as an affront to principles of environmental and economic justice in this lower-income community.
Environmental impacts, particularly in disposing the remaining brine wastes after seawater is desalted, make desalination unacceptable to many conservationists.
Business leaders and some county supervisors are more receptive, saying projects like this need consideration because of increasing uncertainty about water availability.
Huge unknowns exist regarding its total cost and financing, particularly since the study assumes the federal government would pay half the project's construction tab.
In a memo this month to the Pima County Board of Supervisors, County Administrator Chuck Huckelberry said he's not recommending immediate action on this proposal.
He wants it tossed into the mix of ideas that will receive serious discussion in an ongoing Lower Santa Cruz River Basin study done by the U.S. Bureau of Reclamation as a way to help the Tucson area map solutions to its chronic water problems.
"The value of the option is primarily to have a high-level idea of what it would take to bring a truly sustainable, renewable source into the region," Huckelberry wrote in an email to the Star.
CAP shortages loom
That CAP shortages will occur is a certainty. The U.S. Bureau of Reclamation announced on Aug. 16 the first shortage for 2022, cutting about a third of the project's supply. Most of those cuts will fall upon Pinal County farmers.
A second round of cuts is very possible in 2023 if Lake Mead falls to the levels that the bureau is now forecasting. Those cuts will affect several tribes including the Tohono O'Odham and some Phoenix-area cities, but not Tucson.
Tucson wouldn't take any cuts until Lake Mead dropped below 1,025 feet, compared to levels in the 1,060s forecast by the end of 2021. That is considered unlikely to occur until 2025 or 2026 at the earliest.
Tucson Water has said that even in the worst case, it doesn't expect to lose more than half its annual CAP supply and can still deliver adequate supplies to customers with a 50% cut. Even with a 75% cut, utility officials say they believe they can deliver adequate supplies without having to return to the massive over-drafting of groundwater that occurred here from 1940 to 2000.
The new Pima County study charts an alternative course if such forecasts prove too optimistic.
Wieduwilt's "gut feeling" is that the state will always get some CAP water. And if the Tucson area can still get some water from CAP and reduce water demand significantly, "we may never need this project," he said.
But projects like this should be talked about "in case we can't manage the water resources that we have," he said.
"In the next couple of decades we have to really start planning. The projections of climate change don’t show things getting better. Can we adjust our water usage as the supply is reduced before we have to bring in additional outside water?" Wieduwilt asked.
"I think that’s the challenge to the community."
Envisioned for Gulf of California coast
The study proposes running the pipeline project six feet underground from Puerto Libertad, Sonora, on the Gulf of California coast, a town of about 2,800 people lying almost 100 driving miles south of Puerto Peñasco or Rocky Point. The Gulf of California is also known as the Sea of Cortez.
The project would rise from sea level at the coast to 3,853 feet at the U.S. border, putting the desalinated water into three pipelines because the study concluded that would be the most efficient way to get it uphill.
From there, the water would be channeled into one large pipeline, to take it downhill to 2,317 feet at Tucson Water's Southern Avra Valley Storage and Recovery Project recharge basins.
There, it would be recharged into the aquifer and pumped up for delivery into the urban area, just as the city does now with CAP water kept there.
The pipeline would avoid some environmentally sensitive areas such as the Buenos Aires National Wildlife Refuge and the Tohono O'Odham Nation, although it would pass through open space ranchland in the Altar Valley.
From northern Sonora to the Avra Valley, it would follow the path of an existing, 36-inch diameter natural-gas pipeline.
Energy would be the biggest cost
The project's highest costs would be for energy — to remove salts from the water and pump the water uphill. The report pegs those at 35% to 40% of the entire tab.
The county analysis didn't try to figure out where the power would come from.
It relied on energy use and cost estimates supplied by the International Boundary and Water Commission when it conducted a 2020 study of desalinating Sea of Cortez water and piping it north to Morelos Dam at the U.S. border, south of Yuma. That study looked at the possibility of the U.S. and Mexico agreeing that Mexico would get desalted water and the U.S. would get some of Mexico's share of Colorado River water in exchange.
The county study put the project's cost at sharply higher levels than for most desalination plants, but it said that's due to the additional cost of building the pipeline.
The county assumed that going forward, the technology of desalination would require less energy than it does now, "and we are already seeing studies to that effect," Wieduwult said.
"We've been looking at publications of cutting edge technology, of improving membranes used to remove the salts, and more efficiency in operations," he said. "How far off are they? I don't know."
Many costs not yet factored in
But the report acknowledged a long list of "excluded costs." They included the management of the brine; expenses in getting permits; protection against earthquakes; and the costs of building power generation, transmission and electric substation facilities for the plant.
Other excluded costs were land acquisition for the pipeline and the cost to build larger facilities to treat and deliver additional water if Mexico demands it.
Cost aside, simply managing the brine is the desalination project's biggest challenge, said Wieduwilt, adding the study didn't analyze that issue.
"It's a huge impact. Whether you are discharging it or drying it, every method has an Achilles heel. Some places dry the brine to recover salt from it, but you're then talking about a large area that becomes unusable, toxic to birds and wildlife, and then management of it. It’s not a perfect solution."
To figure out the effects and possible mitigation tools would take a full-scale environmental assessment, he said.
As for getting federal money to build this project, U.S. House Natural Resources Committee Chairman Raúl Grijalva said that for now, Congress first needs "a deep and expensive study as to what this pipeline means, what environmental impacts will occur? Are we diverting water from the environment, hurting fish and wildlife? What will we do with salt discharges and the waste?
"I think the idea of desalination and this pipeline is not going to go away," The Tucson Democrat added. "As this mega drought continues to affect the basin states, including Arizona, there is going to be a look beyond recycling, conservation, beyond 'making do with what we have' strategies.
"But I don’t want to jump in and say I would support a $2 billion line item at this point. There has to be a real study done."
Such a project would best be implemented in partnership with the State of Arizona, the CAP and, most importantly, water users including farmers, tribes and municipalities that currently rely on "the existing, built infrastructure of the Central Arizona Project," Tucson Water added in a statement. It noted that desalination is also being evaluated by many Arizona water providers.
Opposition from environmentalists
To Conner Everts, a longtime desalination critic in Southern California, the brine issue is one of many of the aforementioned Achilles heels for this "fantasy" project.
He's concerned about taking water from the Sea of Cortez when it's already been impacted by the historic draining of the Colorado River upstream to serve human needs.
Plus, the proposal ignores that desalination is the most energy intensive source of water, he said. The energy needed to treat and pump this water only continues a "cycle of insanity" of energy use contributing to global heating, said Everts, the Southern California Watershed Alliance's executive director.
He unsuccessfully fought a California desalination plant that was built in 2015 in Carlsbad near San Diego, after years of environmental conflicts, and is now fighting a similar proposal for a plant in Orange County that's been in the works for 22 years. It's expected to get a final vote reasonably soon from the state's Coastal Commission, whose 2008 vote in favor of the Carlsbad plant cleared the way for that project's construction.
"It has taken over 20 years to go through the process just to produce California desal in Carlsbad, and it has been vastly more expensive and more impactful than imagined," he said. "What would be it to do a bi-national long pipeline with multiple treatment and pump facilities? Just too complex and expensive."
In Tucson, the Watershed Management Group's Catlow Shipek blasted the proposal on economic grounds.
"To incur this new debt of $60 a month is outrageous, especially from an economic and environmental justice perspective when a significant portion of our community is limited income and the majority of ratepayers are single family residential customers," said Shipek. He is policy and technical director of the group, which helps people practice water conservation and rainwater harvesting.
Building this pipeline next to a gas pipeline could be "an environmental disaster waiting to happen" if the gas line burst or exploded, he said. That could create a massive water shortage if Tucson were relying on an outside water source like that, he said.
His view is that smarter land use policies, widespread rainwater capture and decreased groundwater pumping could bring Pima County enough water from its own watershed to meet its needs.
Sunnier political, business reception
But County Board of Supervisors Chairwoman Sharon Bronson, Supervisor Matt Heinz and Southern Arizona Leadership Council CEO Ted Maxwell said projects like this need serious consideration to try to insure that the region has a sustainable water supply.
"We're in a water crisis," Bronson said. "We have to evaluate our options for a sustainable future and do it with our regional partners, including the Bureau of Reclamation and the Central Arizona Water Conservation District," an agency that runs CAP. "I imagine there are other options. We need to develop a comprehensive approach to water reclamation and to surface water recharge."
She couldn't speculate how long it would take to bring a project like this online — "there are too many variables for me to have an intelligent response. I think we need to evaluate all of our options, and look at the costs and benefits."
Heinz, like Bronson a Democrat, called this project "a pretty interesting concept" and said the county needs to embrace big ideas and new concepts about water management.
"This could very well be one of the viable ones, depending on conditions at the time it’s being considered, the costs, the environmental impacts, everything else," Heinz said.
"I’m pleased to see the county is engaging in very long term planning which I think is especially relevant given the 20-plus year drought we are in," he said.
The leadership council's Maxwell calls desalination "the conversation of the future," adding the community needs to start exploring plans for future water, energy and roads projects, even though they're not needed right now.
"As water becomes not more scarce, but less available, we need to make some good decisions for water. We will start looking more heavily for alternatives even if it comes at increased costs," said Maxwell, who sits on Republican Gov. Doug Ducey's Water Augmentation Innovation and Conservation Council.
"The cost is not matched by the benefits yet," he said, "but we've got a lot of opportunity with improving technology that at some point, we may be able to do it cheaper."