Science & Technology



Why 'cloud seeding' is increasingly attractive to the thirsty West

Sophie Quinton, on

Published in Science & Technology News

CHEYENNE, Wyo. -- Machines that prod clouds to make snow may sound like something out of an old science fiction movie. But worsening water scarcity, combined with new proof that "cloud seeding" actually works, is spurring more states, counties, water districts and power companies across the thirsty West to use the strategy.

In January, a study funded by the National Science Foundation proved for the first time that the technology works in nature. That study, combined with other recent research, has helped make cloud seeding an attractive option for officials and companies desperate to increase the amount of water in rivers and reservoirs.

In Colorado alone, more than a hundred cloud seeding machines are set up in mountainside backyards, fields and meadows. Some older versions of the contraptions look like a large tin can perched on top of a propane tank. New ones are large metal boxes festooned with solar panels, weather sensors and a slim tower.

Their goal is the same: to "seed" clouds with particles of silver iodide, a compound that freezing water vapor easily attaches to. That makes ice crystals, which eventually become snowflakes.

Colorado's $1 million-a-year program has been around since the 1970s and is paid for not just by the state, ski resorts, and local water users but also water districts as far away as Los Angeles that want to increase snowmelt into the Colorado River, which sustains over 30 million people across the Southwest. Currently, most of the river basin is experiencing a drought.

"Everyone starts to get nervous when there's no snow in Colorado," said Joe Busto, the scientist who oversees Colorado's cloud seeding program.

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Major urban water districts in Arizona, California and Nevada have funded cloud seeding in the Rocky Mountains for over 10 years and are now close to signing an agreement with officials in Colorado, New Mexico, Utah and Wyoming to split the cost of nine more years of seeding.

Cloud seeding is a relatively cheap tool for bulking up the water supply in Lake Mead and other reservoirs, said Mohammed Mahmoud, a senior policy analyst for the Central Arizona Water Conservation District. The up to $500,000 annual commitment the district is making to the regional agreement comprises a tiny fraction of its budget, he said.

Yet it's hard to tell how much additional precipitation cloud seeding creates or how much additional snow or rain eventually makes it into city water pipes. Cloud seeding only works when there are freezing, moist clouds in the air. And the technology can be controversial.

"The whole thing is propaganda," said Jamie Kouba, 32, a farmer from Regent, N.D., who argues that cloud seeding is decreasing rainfall in his area, rather than increasing it. He's organizing local farmers in a campaign against the practice.


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