美国国家公共电台 NPR--States dependent on Colorado River wonder if desalination could help the water supply

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States dependent on Colorado River wonder if desalination¹ could help the water supply

Transcript²

Severe drought has states dependent on the Colorado River looking at alternatives. Desalinating seawater may be a viable³ supplement to some areas, but likely can't fix much of the river's deficit⁴.

A MARTINEZ, HOST:

The Colorado River is shrinking. And a month ago, states that rely on it missed a federal deadline to propose ways to drastically cut back usage. So as the search continues for a comprehensive solution, some are asking if a process called desalination could help. As Alex Hager of member station KUNC reports, that particular technology comes with big tradeoffs.

(SOUNDBITE OF WATER RUSHING)

ALEX HAGER, BYLINE⁵: It's a picture-perfect afternoon in Southern California. The sun is beating down on a volleyball game in the sand. And a surfer is paddling out into the waves. And just across the road from the beach, this salty seawater is getting a new life at the largest desalination plant on the continent.

(SOUNDBITE OF WATER POURING)

HAGER: Michelle Peters, the plant's technical manager, pours a glass from the tap.

MICHELLE PETERS: At 10 a.m., you have the morning surfers swimming in it just off the - you know, off the coast in the ocean here. Carlsbad - now it's high-quality drinking water, ready for consumption.

HAGER: Peters explains how this plant pulls from the ocean, removes the impurities⁶ and salt and makes that water drinkable. She walks through a sprawling⁷ web of tanks and pipes where the breeze delivers an occasional whiff of low tide.

PETERS: This is where the magic happens. This is really what makes desal desal. It's the heart of the site.

HAGER: Desalination isn't affected⁸ by drought. And San Diego County, which gets most of its water from the Colorado River, added this facility to make themselves less reliant on water sources that could dry up. With federal managers asking states all around this parched⁹ region to make huge cuts in the water they use from the Colorado River, some are asking if plants like this could help other states. Earlier this year, for example, Arizona Governor Doug Ducey proposed funding a new desal facility across the border in Mexico in exchange for some of that country's Colorado River water.

(SOUNDBITE OF ARCHIVED RECORDING)

DOUG DUCEY: Instead of just talking about desalination, how about we pave the way to make it actually happen?

HAGER: But taking water from the ocean comes with a catch. It costs a lot of money just to make a little water ready to drink. And that water costs a lot to move. The whole thing is really energy-intensive.

JAY LUND: If they got desperate enough, that could work.

HAGER: Jay Lund studies the economics of water at the University of California Davis. He says before turning to desalination, cities should look to other ways to stretch their water supply - getting rid of lawns, capturing stormwater and recycling wastewater. And there's one other big alternative on his mind.

LUND: The bulk of the new water is almost certainly going to have to come from fallowing some of the agriculture, which is already most of the water used in the Western states.

HAGER: Nearly 80% of the water from the Colorado River is used by that sector¹⁰. And fallowing - or paying farmers and ranchers to pause growing on their land - would free up supply. While experts agree that desalination isn't going to solve the Colorado River crisis, Sharon Megdal, who studies water policy at the University of Arizona, says the Southwest shouldn't write it off completely.

SHARON MEGDAL: When we're looking at the full mix and the full portfolio¹¹, I think there's a role for desalinated seawater. And the fact is it will take time to get projects permitted and built, and so you have to think ahead.

HAGER: Megdal says desalination is still worth more research. Even though it may not be a silver bullet, it could be a small part of diversifying¹² the water supply in some areas as the Colorado River keeps drying up.

For NPR News, I'm Alex Hager in Carlsbad, Calif.

(SOUNDBITE OF DIRTY PROJECTORS SONG, "STILLNESS IS THE MOVE")