Pitkin County board still unsure on cloud seeding risks

Larry Hjermstad of Western Weather Consultants with cloud seeding equipment in October 2017.
Hugh Carey / Summit Daily file photo

Cloud seeding appears to pose little risk to human health, though questions remain about adding a heavy metal to the environment.

That was the word Tuesday from members of the Pitkin County Board of Health and county officials who looked at the direct human risk of using silver iodide to prompt larger snowstorms. The Board of Health recommended that Pitkin County commissioners support cloud-seeding efforts, though board members weren’t quite ready Tuesday to commit to the project just yet.

“I’m not supportive of the county funding any cloud seeding,” said Commissioner George Newman, noting that Aspen Skiing Co. officials have said their previous cloud-seeding efforts appeared fruitless. “So, I don’t see us getting involved in cloud seeding at all.”

Other commissioners, however, weren’t ready to dismiss the effort.

“I think it’s still worth exploring,” Board Chairman Greg Poschman said.

Commissioners asked the Board of Health to look at the issue from a harm-to-humans standpoint based on a request from a state water agency that wants to increase cloud-seeding efforts in the Roaring Fork Valley. And while the board agreed that current research indicates that concentrations of silver iodide involved in cloud seeding pose a low risk to humans, they also had concerns, according to a memo to commissioners from Public Health Director Karen Koenemann.

The board had a “robust discussion” about adding heavy metals to the environment and whether that alters micro-organisms, animals and fish, and possibly affects people with chronic illness, the memo states. And while the board recommended supporting cloud seeding, it also recommended installing a long-term monitoring program as well if the board decides to fund it.

An official with the Colorado River District asked commissioners in November to contribute $25,000 to an effort encouraging more cloud seeding in the Western Slope. Commissioners declined, saying they wanted more information about the health and environmental impacts of vaporizing silver iodide to encourage ice crystal growth in winter storm clouds.

Kurt Dahl, the county’s environmental health manager, said Tuesday that commonly accepted research indicates that cloud seeding can increase snowpack 10 percent to 15 percent. However, it doesn’t work in drought years because it needs storm clouds to work, so it must include water storage plans, as well.

Board of Health member Brent Miller also said Tuesday he thought $25,000 was a “good price” to pay for a project that is “generally accepted to be effective.”

Commissioner Patti Clapper, however, wasn’t convinced.

“I agree with George,” she said. “I’m really sensitive about adding heavy metals to the environment. It’s something we can keep an eye on. But I’m just not there yet at this time.”

But Poschman pointed out that cloud seeding has been going on for decades in Vail, which should have yielded some studies on any environmental effect. Commissioner Kelly McNicholas Kury also said she thought answers existed to cloud-seeding environmental concerns.