Idaho Looks to Cloud Seeding to Enhance Winter Snowpack

Jan 2, 2013

A cloud seeding operation near Idaho City.
Credit Aaron Kunz / EarthFix

Cloud seeding has been around for decades. It started out as a way to make rain for growing crops. But in the Mountain West, it’s used these days as a way to make more snow.

Cloud seeding is often misunderstood. It’s the process of increasing the amount of rain or snow fall when a storm system moves through.

“When you look at cloud seeding, it’s a water management tool -  it’s not something that we use to eliminate a drought," says Derek Blestrud. 

Blestrud is a meteorologist with Idaho Power. The utility pays for and operates two cloud seeding programs in Idaho. Today, there are 36 cloud seeding towers. Blestrud and Brandel Glenn took us to one of the cloud seeding machines located on a mountain ridge above Idaho City. Glenn is a field engineer for Idaho Power.

A 26-foot tower with a lattice structure with a burn head that burns propane and produces a plume rising into the sky.

There are various methods of cloud seeding. Most of them involve a material called silver iodide. Picture a compound that looks like tiny metallic shavings.  You can drop silver iodide out of an airplane or fire it into the air by cannon or burn silver iodide using propane mounted to a tower -- that’s the method used by Idaho Power.

In either case, silver iodide attracts water droplets in the air. And because its silver iodide, those water droplets freeze and fall to the earth as snow.

Idaho Power’s cloud-seeding tower is powered by a small solar panel, providing enough power to run a satellite modem. That's so meteorologists can turn it on and off from the Idaho Power building in downtown Boise.

Scientists measure temperature and humidity at the Idaho City site as part of a process they admit is not very dramatic.  .

Cloud seeding isn’t new, some early projects here in the Northwest happened as early as the 1940s. But despite the fact it’s been around for decades, there are still questions about how effective it really is. Cloud seeding also generates controversy about the effects it has on the environment.

Early on, cloud seeding was used to bring rain to irrigate crops. These days, it’s used to coax more snowfall. Idaho Power is seeding clouds as part of its strategy to make sure there’s enough runoff from melting snow in the summertime. That translates into water in rivers -- and more water means more power generated from those rivers’ hydroelectric dams.

Credit Aaron Kunz / EarthFix

Blestrud says Idaho Power has done research that shows its cloud-seeding is adding 15 percent to the snowpack. That’s about two more inches of snow for every foot of snowfall.

“If you get more snow pack that's higher up in the mountains, that’s the stuff that comes off last," Blestrud says.

The deeper the snow is, the longer it stays cool in the spring and early summer. And that helps the snow sticks around longer.

Brandel Glenn, with Idaho Power, says snowpack in the highest mountains means more water during the warm months.

For Idaho Power, it means more water to turn the turbines at its many dams.

“And the amount of power that can be generated from this is roughly 100,000 megawatts which is enough to power about 700,900 homes for a year," Blestrud says.

But it may have fringe benefits that go beyond electricity production. Blestrud says the added snow from cloud seeding means more water for recreation and for farmers and ranchers to use to irrigate their crops and hayfields.