The Western water crisis is turning to an 80-year-old solution: Shooting crystals at clouds

This coming winter, residents in the American West may glance up to the sky and see planes shooting tiny particles at clouds. That might sound like something from a sci-fi flick—but it’s a legitimate effort to create more water during a megadrought that’s now in its 23rd consecutive year.



The technology, cloud seeding, is a process of stimulating clouds to produce more precipitation, and has been around for more than 80 years. It’s been used in different ways through history, but there’s growing research and interest—and an inflow of federal funding—as Western states struggle to deal with water shortages. Though far from the only solution, it’s viewed as one tool that could help reduce dangerous deficits.



When cool droplets accumulate in clouds, many are too small and light to descend downwards, and simply hover in the sky. Cloud seeding is the process of making those droplets bigger so they fall to the ground, by injecting the clouds with a bulking agent, silver iodide. The compound is either burned on the ground and rises up into the clouds—or shot at the clouds from airplanes, which is more effective but costlier. Either way, the idea is to “get more out of those clouds,” says Katja Friedrich, associate chair of the Department of Atmospheric and Oceanic Sciences at the University of Colorado.



“The basic concept of cloud seeding is actually not debatable, because we know that it works,” Friedrich says. The technique has been around since the 1940s, when meteorologist Vincent Schaefer took the first flight to release a seeding agent—dry ice—into clouds. “Ice would be a perfect feeder, but it’s really difficult to get the ice into the aircraft,” Friedrich says. Silver iodide acts as a more manageable option that has a suitable crystalline structure.



Today, the concept is having something of a renaissance, as the West searches for solutions to its water crisis. It’s in the middle of what may be the most severe drought since 800 AD; groundwater is drying up, and there’s a fight over the critical supply from the Colorado River, largely between California and the six smaller states in the river basin. (The Biden administration recently recommended resources be split evenly, despite a “seniority” rule that California uses to justify pushing to the front of the line.)



Cloud seeding has been used in different ways, including to create rainfall in the UAE and Texas, and to shrink hail in Canada. But in the West, seeding focuses on orographic—wintertime—clouds in mountainous areas, to increase snowfall between November and March. The idea is for cloud seeding to help increase yearly snowpack, an effective way of storing water, in reservoirs. That’s crucial now: In 2022, water in Lake Mead, the largest reservoir in the area, dropped to the lowest levels since 1937.



Colorado, Nevada, and Utah have been seeding for decades; Wyoming since 2014; and New Mexico gained approval last year for its southeastern mountains. Arizona doesn’t, though the Salt River Project, a water and power supplier in the state, is looking into the feasibility, in collaboration with the White Mountain Apache Tribe. “I think a lot of states are doing this out of desperation,” Friedrich says.



It’s proven effective in producing an increased snowpack; results vary, but studies have shown an uptick of 5% to 15% on average. Friedrich’s work has been focused in mountainous western Idaho since 2017, where her team monitored seeding performed by Idaho Power. “We were piggybacking on what was going on already,” she says.



Her project, Seeded and Natural Orographic Wintertime Clouds: the Idaho Experiment—more catchily known as SNOWIE—was focused on creating a numerical model to quantify water produced, because historically it has been hard to test what a cloud is doing naturally versus thanks to the silver iodide. “I think this gave the entire cloud seeding industry a boost,” she says.



But there are issues. SNOWIE found that seeding produced an average of 100 acre feet in one day, which is something, but “not a lot,” Friedrich says. It’s also hard to know which clouds have the right droplets, and difficult to target them. And the process adds silver iodide to the atmosphere, which could run off into the groundwater. There’s a possibility if it lingers that it could be toxic to certain mammals and aquatic life.



Still, it could be effective if scaled up, especially if funding increases. Last month, the federal government granted $2.4 million for seeding via the U.S. Bureau of Reclamation. States have already been funding projects, and budgets are increasing: Utah has dedicated $14 million to it for next year.



It’s not the only solution to the water crisis, but can be a part of an array of conservation actions. “I think we need to take anything that we have available to mitigate it,” Friedrich says. “I think this comes down to: What’s the cost of water, and how desperate are we?”