Legislators consider desalination as solution to Arizona water shortage

At its most basic, desalination is the process of removing salt from water.

But for Arizona, it will be much more complicated because it's not just about the water.

Lawmakers from Arizona to Washington D.C. to Mexico will need to come to a consensus about how to get it done.

The Binational Study of Water Desalination Opportunities in the Sea of Cortez released in 2020 looked at various scenarios to determine if a joint desalination project is feasible.

Commissioned by Central Arizona Project (CAP), Southern Nevada Water Authority, Salt River Project and mining company Freeport-McMoRan, the report concluded a desalination project is feasible. 

One of the options would build two desalination plants along the coastline of the Sea of Cortez in Mexico.

The treated water could stay in Mexico in exchange for allowing the U.S. to keep a portion of that country's Colorado River allotment.

"The technology is there. The question is related to the costs and the environmental impact," said Sharon Megdal, who heads up the University of Arizona's Water Resources Research Center.

Megdal has been working on water policy and management in Arizona for 30 years. While not involved with the study, she has studied desalination plants around the world and said they come with significant challenges.

Cost being one of the biggest.

The study estimated $4.5 billion to $4.9 billion to bring the plants online.

The costs to operate the plants could range from $148 million to $197 million annually.

The amounts are well above what users currently pay.

For context, in 2023, water that comes from the Colorado River through CAP canal will cost users an average of $270 per acre-foot.

Estimated costs of water from desalination plants in the study could reach $2,200 per acre-foot.

But Megdal said only a fraction of seawater that goes through the process is useable.

"It's more like a 50% throughout," she told ABC15. "So for every gallon, if we just talk about gallons you put into the process, you'll get a half gallon of good quality water, and then a half gallon of brine to dispose."

And the question of what to do with all that brine, or heavily salted water, has complicated answers.

Desalination supporters point to the country of Israel as a model.

"This is what allows Israel to be a global growth dynamic state because they solved their water issue," Governor Doug Ducey told ABC15.

Ducey and an Arizona delegation visited desalination plants in that country earlier this year. Its five seawater desalination plants provide most of the tap water for its 9 million residents.

He recently told ABC15 that Arizona is close to a deal on desalination too.

"We are in the final stages of the desalinization project which we’ve invested in, and will complete before we leave office," he said.

"Israel is often looked at, as it should be, as a success story for dealing with water scarcity," Megdal said. One of her visits to Israeli plants is highlighted in the documentary Beyond the Mirage.

But she pointed out that there are real differences between a sovereign Israel and the state of Arizona.

One of them is that Israel has a readily available source of water since it borders the Mediterranean Sea.

She said another difference is their centralized approach to the governance of water.

"They have a master plan for water for the whole nation, the whole region, and they follow it," Megdal said.

That includes what to do about brine, which largely ends up back in the Mediterranean Sea.

"There are concerns about the impacts of marine life," Megdal said. "If there are plants being operated for many years, what is the cumulative impact of the brine disposal?"

Still, she says desalination should not be counted out. But it can't be counted on as the only solution.

"You kind of build a portfolio, and you build something that's resilient, and going to carry you through. And that means you don't bet on just one option, but you look at multiple options," she said.