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Seawater Tempting, Costly Drought Defense for Landlocked Arizona

Jan. 13, 2022, 4:50 PM

Arizona Gov. Doug Ducey’s plan to remove salt from seawater as an antidote to the landlocked state’s intensifying drought overlooks what water lawyers say is the best medicine: using less water.

Ducey (R) said this week he is working with Arizona Republican leaders to invest $1 billion over the next three years on a state initiative to build large-scale water augmentation projects.

The plan to secure the state’s water supply for the next century includes desalination, an increasingly common global solution to obtain fresh water but one more closely associated with coastal states such as California and countries such as Israel.

The state is considering many different options for desalination. It might mean spending billions to remove salt from water in the Sea of Cortez and pipe it across the Mexican border or send it to Mexican farmers as part of a complex international water exchange, Ducey’s top advisers said.

The idea has the support of Sen. Mark Kelly (D-Ariz.).

“The Sea of Cortez isn’t too far away” and Arizona doesn’t have its own source of saltwater, Kelly told Bloomberg Law. “Anything we do would have to be off the California coast or the Gulf of California. It’s a realistic thing.”

‘Is There Really a Need?’

But there are better and cheaper ways to secure the water supply, including aggressive conservation measures, raising water rates, re-using waste water and striking water deals with farmers, said Robert Glennon, an emeritus water law professor at the University of Arizona.

“Everyone thinks the Sea of Cortez is the Holy Grail,” he said. “The question will be asked: Is there really a need to do this?”

While Ducey doesn’t have a specific project in mind, desalination remains his top choice for long-term water strategy, his advisers said.

Most of Arizona has been in a near-continuous state of drought since 2002. The state’s long-term water security, which depends on the over-extended Colorado River, is uncertain as climate change and thirsty growing cities threaten the river’s available water.

‘One Option’

The Sea of Cortez, just 50 miles across Mexico from Arizona’s southern border, is tantalizing for those worried that Arizona will run out of water.

Officials in the Tucson area have envisioned piping Sea of Cortez water nearly 200 miles across the border to augment Pima County’s water supply. But the most widely studied option involves building a plant along the coast and swapping water with Mexico.

The state participated in a 2020 study sponsored by the International Boundary and Water Commission into a complex water exchange with Mexico involving a $3 billion water desalination plant along the Sea of Cortez.

It envisioned Arizona and the federal government helping to pay for the desalination plant, which would produce fresh water for Mexico and allow the state to keep some of the Colorado River water that it’s legally bound to provide to Mexico each year.

Some environmental groups support desalination despite concerns about the environmental costs of brine disposal.

“Climate change is here, we’re going to need new things and desalination in the Sea of Cortez is one option,” said Haley Paul, policy director for the National Audubon Society in Arizona.

‘Very Expensive Water’

But some of the West’s most prominent water law experts are skeptical that desalination will solve the state’s long-term water woes.

“Practically, this would be very expensive water,” said Larry MacDonnell, a former water law professor and emeritus member of the Colorado River Research Group at Utah State University.

The International Boundary and Water Commission estimated that the energy required to desalinate 100,000 acre-feet, or about 32.6 billion gallons, of Sea of Cortez water each year would cost up to $119 million annually, including an electric bill that could cost as much as $86 million.

Desalination elides the growing need for water conservation, MacDonnell said.

“Most observers believe the only practical approach to ongoing shortages is to reduce existing uses,” MacDonnell said.

Mexico’s interest and cooperation also isn’t guaranteed, despite its support of the international commission study, he said.

“There has to be something in it for the Republic of Mexico,” he said. “You can’t be the crazy state just coming in and trying to locate something in another country and think you can get away with this.”

The international commission will further study Sea of Cortez desalination opportunities, said its spokeswoman, Lori Kuczmanski. It’s also planning a second-phase study of the issue once the Mexican state of Sonora appoints a representative to the group leading the study, she said.

To contact the reporter on this story: Bobby Magill at

To contact the editor responsible for this story: Chuck McCutcheon at