More turn to cloud seeding to fight drought
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 evidence that “cloud seeding” can work, is spurring states, counties, water districts and power companies across the thirsty West to use the strategy.
Last month, a study funded by the National Science Foundation tracked for the first time how the technology works in nature. The evidence for cloud seeding has been scarce, but recent research has encouraged officials and companies desperate to increase the amount of water in rivers and reservoirs.
In Colorado alone, more than 100 cloud seeding machines are set up in mountainside back yards, fields and meadows. Some older versions of the contraptions look like large tin cans perched on top of a propane tanks. 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 combination makes ice crystals form, which eventually become snowflakes.
Colorado’s program, which costs $1 million a year, is paid for not just by the state, ski resorts and local water users but also by water districts as far away as Los Angeles that want to increase snowmelt into the Colorado River, which sustains more than 30 million people across the Southwest. 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.
Major urban water districts in Arizona, Pacific Gas and Electric Meteorological Technician Steve Tissot climbs a ladder to inspect a cloud seeding machine in 2009 near Lake Almanor, Calif. Faced with crippling droughts, governments and utilities throughout the western states are turning to cloud seeding as a way to get more rain and snow out of the clouds.
California and Nevada have funded cloud seeding in the Rocky Mountains for more than 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.
Yet it’s hard to tell how much additional precipitation cloud seeding creates. The processworks only 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.
Cloud seeding machines generate smoke that floats into the air like incense. Some state programs rely on ground-based machines. Others use airplanes to drop flares that generate silver iodide smoke into clouds, or to fly into a storm with flares strapped to their wings.
The recent study, which was conducted in Idaho and published in the Proceedings of the National Academy of Sciences, was the first to show real-world observations of silver iodide forming ice crystals inside clouds and falling out as snow.
Such research has increased interest in cloud seeding, particularly among private companies and utilities, said Neil Brackin, president of Weather Modification, a North Dakota company that does cloud seeding.
Other recent studies have used computer modeling to estimate the increase in snowfall from cloud seeding. A 2014 study across two Wyoming mountain ranges found that cloud seeding could increase snowfall by 5 percent to 15 percent — but only when the right conditions for seeding were met, or during 30 percent of snow events.
Relatively small increases still matter. “People in the western United States — we’re always water-stressed out here,” said Frank McDonough, an atmospheric scientist in Nevada who oversees the cloud seeding program at the Desert Research Institute, part of the state university system. Along the Colorado River, more water is promised to people than is available.