What you should know about desalination, proposed by Gov. Doug Ducey as a solution to Arizona's water crisis

During his final state of the state address on Jan. 10, Governor Doug Ducey proposed setting aside $1 billion to bring desalinated water to Arizona.

"Speaker [Rusty] Bowers, President [Karen] Fann and I have been working, and we propose that we make a historic investment: $1 billion," said Gov. Ducey. "Our goal: secure Arizona’s water future for the next 100 years."

Here's what you should know about desalination.

What is desalination?

According to the United States Geological Survey, desalination is the process of turning saline water, or water with significant amounts of dissolved salts, into freshwater.

Figures from a United Nations study in 2018 show there are now almost 16,000 desalination plants operating in 177 countries. In the U.S., various cities and regions, such as South Florida, California's San Diego County, Santa Barbara, and El Paso, Texas have desalination plants.

How long has the technology been around?

Desalination, in various forms, has been around since ancient times.

According to the USGS, desalination, in the form of boiling water, capturing the steam and condensing it back into water, has been around since ancient times as a way for ships to convert sea water into drinking water.

Besides what is known as distillation, USGS officials say desalination can also be done by forcing the saline water through filters that blocks salt molecule but allow water molecules through.

"Reverse osmosis is an effective means to desalinate saline water, but it is more expensive than other methods. As prices come down in the future the use of reverse osmosis plants to desalinate large amounts of saline water should become more common," a portion of USGS's website reads.

What does Gov. Ducey's desalination plan entail?

While Gov. Ducey previewed the plan, he offered few details during the address, nor did he say where he’d like to build a desalination plant.

However, water policy experts have long discussed the possibility of using water from the Sea of Cortez in Mexico, the nearest sea to Arizona.

Isn't there already something like this in Arizona?

Yes.

According to the Bureau of Reclamation's website, there is a "desalting plant" in Yuma that treats drainage water, and the treated water is intended to be delivered to Mexico, thereby preserving the same amount of water in Lake Mead.

"Construction of the plant was completed in 1992, and it has operated on two occasions since then," read a portion of the website. 

According to the website, the plant's stated purpose of delivering treated water to Mexico could save the U.S. up to 97 million cubic meters, or 78,000 acre-feet, of Colorado River water per year.

According to a document released by the City of Phoenix, residential water demand was 171,913 acre-feet in 2019.

What are the challenges of desalination?

Officials with the United Nations Environment Program say in most desalination processes, every liter of drinkable water produced also creates about 1.5 liters of liquid that is polluted with chlorine and copper, known as concentrate.

"This wastewater is twice as saline as ocean water. If not properly diluted and dispersed, it may form a dense plume of toxic brine which can degrade coastal and marine ecosystems unless treated," read a portion of the UNEP's website.

In addition, desalination might not solve all of Arizona's water problems. A 2018 article published by the Associated Press highlighted water problems that Israel is facing, despite the country having invested heavily in desalination technology.

It was noted in the article that years of decreased rainfall reduced the country's main natural water source, the Sea of Galilee, to some of its lowest recorded levels, prompting the country to stop pumping water from it. Those same drought conditions also dried up tributaries that feed into the Jordan River, which flows into the Sea of Galilee and then into the Dead Sea.

"Israel definitely put conservation on the backburner. As soon as desalination plants were up and running there was this false sense of security, and water consumption rose," said Sarit Caspi-Oron, director of the water department at the Israel Union for Environmental Defense, an advocacy group. "Desalination doesn’t make up for everything, and when groundwater is suffering from drought and the Sea of Galilee is suffering from drought, you need to conserve."

In his state of the state address, however, Gov. Ducey appears to look at Israel as an example.

"Instead of just talking about desalination – the technology that made Israel the world’s water superpower – how about we pave the way to make it actually happen?" said Gov. Ducey.

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