Cloud seeding

In this September 2017 photo, Eric Hjermstad, of Western Weather Consultants, demonstrates a cloud seeding generator in Silverthorne. Western Weather Consultants claims that its two seeding operations in the High Country generate between 180,00 and 300,000 added acre-feet of water per year, and that has been backed up by independent studies. Pitkin County commissioners on Thursday discussed participating in a cloud seeding effort.

Skeptical Pitkin County Commissioners on Thursday, after a briefing on the potential boon and possible negatives of blasting silver molecules into clouds above the Roaring Fork Valley to boost snowfall, said they would like to hear more information about the expanding science of cloud seeding before approving a funding request.

Dave Kanzer, deputy chief engineer with the Colorado River District, went before the officials as his agency seeks a $25,000 grant from the county, an effort that may aid more moisture on the slopes and in rivers — and one that is already taking place around Colorado and other Western states amid severely dry conditions.

For those who have watched river levels over the past two decades, “it’s really no longer a drought, it’s a new normal … where water-supply issues are becoming acute,” he said.

The proposal is part of a larger set of “augmentative” initiatives throughout the Colorado River basin that involve seven other states.

Studies in Idaho and Wyoming, in particular, have updated the science of such initiatives in cold weather, Kanzer said. The research, which involved comparisons between seeded and unseeded areas, found that the skyhigh efforts “positively affirmed the effectiveness of cloud seeding,” he said, though he later allowed that “quantifying the results is tricky.”

Three ground-based generators, which vaporize and release into the air minute quantities of silver that become dust-sized particles, are already in the valley. Silver iodide is sprayed across the generator’s propane flame, and roughly 15 to 30 minutes later, if the process works — it’s effective in only about 30 percent of storms — ice crystals grow large enough to fall to the earth as snow. Wind speed, temperature and air pressure are among the conditions considered before the generators are fired up.

The devices are “somewhat simple,” and authorities sometimes rely on ranchers on remote areas to fire them up, he said.

Seven federally permitted programs in Colorado that cost roughly $1 million a year exist.

“There’s a lot going on in Colorado,” Kanzer said. “There are over 100 [sites] in western Colorado, from the southern San Juans all the way up to Grand County, that are actively engaged in cloud seeding.”

The effort is connected to a roughly $500,000 agreement with Arizona, California and Nevada in the lower Colorado River basin — “all in an effort to effectuate increased water supply,” he said.

Commissioner Patti Clapper asked about the total need of the silver-infusing generators, and their health effect.

“What’s the cumulative effect if you added a hundred or more generators spewing silver nitrate into the atmosphere?” Clapper asked. “What’s the cumulative health risk of that?”

Kanzer said that, based on studies, the cumulative effects on health are negligible.

Vail and Beaver Creek officials have been engaged in the effort since 1975, “and they are sold on it.” Winter Park, Keystone and Breckenridge are also involved.

But Rich Burkley, an Aspen Skiing Co. vice president, said of the science: “We could just not prove it, one way or the other. … There’s not really a reasonable business decision to do this.”

On the West Slope, 25 manual cloud-seeding generators and two remote sites operate up to five months from November to April, with the target areas being above 8,500 feet in Pitkin, Eagle, Summit and Grand counties, “where most of the snow falls,” Kanzer said.

The efforts could result in an extra 60,000 acre feet of water in the region’s rivers, so a small percentage of cloud seeding across a large landscape “yields a lot of water,” he said. “We understand there is a lot of skepticism in that. The point is, it’s a low-risk, high-reward scenario.”

Commissioner George Newman called the results thus far of studies showing the airborne silver’s possible long-term ramifications to residents’ health “nebulous,” comparing it to cigarette and lung cancer data.

“To me, this is appealing because it is the only way to increase the quantity of moisture in our snowpack and in our watershed to a measurable degree,” Commissioner Greg Poschman said. “If we can pull 5 percent more moisture out of the clouds, maybe that will help us get through the next five weeks of no snow. We have to look at how our weather is shifting.”

Chad is a Contributing Editor for Aspen Daily News. He can be reached at or on Twitter @chad_the_scribe.

Contibuting Editor