Utah put millions into cloud seeding this year. Here’s what it expects in return.

Regulators are spending millions to install snow generators across the state. And they expect decent precipitation as a result.

(Francisco Kjolseth | The Salt Lake Tribune) Fresh snow blankets the Salt Lake Valley as the sun sets on Mount Olympus on Wednesday, Jan. 18, 2023.

Lawmakers opened the financial floodgates this year, pouring an unprecedented amount of money into Utah’s decades-old cloud seeding program.

The Division of Water Resources has used the windfall to install dozens more seeding sites in mountain ranges across the state, some of which can get deployed remotely via a cellular network. It’s also adding two aerial could seeding missions, funding plane deployments in both southern and northern Utah. Efforts were previously conducted with on-the-ground stations that had to be switched on by hand.

“It’s pretty exciting,” said Candice Hasenyager, the division director. “This offers a lot of opportunity to seed in areas where we could have never seeded before.”

(Utah Division of Water Resources) Planes carrying silver iodide inject the material into storm clouds, which helps generate ice crystals and increased snowfall.

Each cloud-seeding generator and flight injects silver iodide into clouds, encouraging them to form ice crystals, which turn into snowflakes, which means more water falling on parched Utah’s mountain peaks.

All said, the Legislature earmarked $12 million in one-time funding for cloud seeding in 2023, along with $5 million in ongoing funding for the program moving forward. That’s a big boost from the $200,000 to $350,000 lawmakers had previously allocated for the program in recent years.

Joel Ferry, the director of the Department of Natural Resources, pushed for more cloud seeding funds during the last legislative session. Although the new appropriations may seem substantial, he said the program produces water at a cost of between $2 and $15 per acre-foot. An acre-foot is around enough water to supply two households for a year.

“When you compare that to anything else that we do,” Ferry told a group of scientists and stakeholders at the state’s first-ever Cloud Seeding Symposium on Thursday, “it is hands-down a fraction of the cost of any other water [conservation] program,” like turf buyback and secondary water metering.

(Utah Division of Water Resources) Attendees of the Utah Cloud Seeding Symposium tour a remote snow generator system at Snowbird on Thursday, Sept. 28, 2023.

Utah’s resource managers plan to use the funds to add 60 manual generators to its existing network of about 170 sites. It will also install 120 remote generators they can fire up from afar.

The state contracts its cloud seeding services to Sandy-based North American Weather Consultants, or NAWC, which has been in the business since the 1980s.

“We’ve reached barriers where we can’t seed it in areas where we’d like to be seeding,” said Garrett Cammans, president of NAWC, “particularly high-elevation locations, because they rely on a manual operator to go out at night and turn on the equipment.”

It’s becoming harder and harder to find people willing to hit those switches, even in lower elevation locations, especially in the cold and stormy conditions that produce snow. With state funds to install remote-operated sites, “this lets us operate where the weather is most active, not where people reside,” Cammans said.

Does cloud seeding work?

For the silver iodide solution to do its job and drop water Utahns can use, certain factors have to be right.

Generators placed in areas prone to inversions, like the Uinta Basin, don’t do much good because the stagnant air can’t move the silver into storm clouds. They also need to encourage storms at high elevations, where snow remains snow throughout winter, and melts when people start needing water in spring. And the targeted clouds need to hold enough water to make the effort worthwhile.

Still, “pretty much most mountain ranges in the state are targeted for cloud seeding efforts” between aerial flights and ground generators, said Todd Flanagan, a meteorologist with NAWC.

That’s making it increasingly difficult to quantify how effective the state’s cloud seeding deployment has been, since NAWC is running out of areas with no cloud seeding to compare with as controls.

In places where Utah has deployed cloud seeding for 20 years or more, Flanagan said, they’ve seen an average of 4% to 13% more water falling as snow. That’s similar to what other states have reported about their cloud seeding programs -- officials with the Idaho Department of Water Resources and Nevada’s Desert Research Institute report increases of about 10%.

(Utah Division of Water Resources) Cloud seeding ground generators use propane to burn a silver iodide solution, releasing it into the atmosphere so it can form ice crystals in storm clouds and create more more snow.

Ferry with DNR and Hasenyager with Utah’s Division of Water Resources acknowledged the importance of using a third party to validate the impact of their cloud seeding program, instead of relying on contractors’ own reports that indicate their efforts are paying off.

“One thing that we’re looking at doing,” Ferry told attendees of the Cloud Seeding Symposium, “is utilizing some of the funding that we received to partner with research institutions [and] validate, how [well] does this work?”

Although the number of control sites are rapidly disappearing as cloud seeding expands across the West, scientists have developed models to show what happens to storms after seeding, and how much water they generate.

“It’s really going to be the future of evaluating these programs,” said Sarah Tessendorf, a scientist with the National Center for Atmospheric Research, or NCAR.

Does cloud seeding ‘steal’ snow that would fall in other places?

A concern raised by rural politicians at the symposium was whether adopting a cloud seeding program in one county would end up “stealing” water that would otherwise fall in another.

Kala Golden, who manages Idaho’s cloud seeding program, said it’s a common concern from stakeholders. She encourages them to think of storms and atmospheric conditions like a river in the sky, which collects and deposits water all along its course.

“It’s not a single cup that dumps out, that your neighbor took ... and then by the time it gets down to you, that cup is empty,” Golden said. “That system is continuing to pick up water as it goes along, just like a surface-flowing river.”

In fact, since 2007, Lower Basin states on the Colorado River like California and Nevada have helped pay for and support cloud seeding programs in Upper Basin states. Contributions from those states amounted to more than $80,000 in Utah during the 2020-2021 season.

“We’re at the end of the pipe,” Tom Ryan, a resource specialist with the Metropolitan Water District of Southern California, said at the symposium. “[We want to] get some folks to create additional snowfall with the hope that eventually it will cascade its way down to Southern California.”

Other parties collaborating with and contributing to Utah’s cloud seeding program include local water suppliers, like the Cache Water District, Weber Basin Water Conservancy District, Central Utah Water Conservancy District and Salt Lake Public Utilities.

“Weather modification is not just a science,” Ferry said in a written statement. “It’s a crucial tool for ensuring water sustainability in our arid region.”