SAN ANGELO, Texas—Inside a small office at the San Angelo Regional Airport, Jonathan Jennings is looking for a big opportunity. He’s checking weather radar for an approaching storm system, so he can send up a plane to chase the moisture-laden clouds.
The pilot will inject them with a spritz of nontoxic chemicals, known as cloud seeding, to boost rainfall on the ground.
“It...
SAN ANGELO, Texas—Inside a small office at the San Angelo Regional Airport, Jonathan Jennings is looking for a big opportunity. He’s checking weather radar for an approaching storm system, so he can send up a plane to chase the moisture-laden clouds.
The pilot will inject them with a spritz of nontoxic chemicals, known as cloud seeding, to boost rainfall on the ground.
“It is like we are taking a dripping sponge and squeezing it,” said Jennings, project meteorologist for the West Texas Weather Modification Association.
Cloud seeding—a technology that has been deployed in various forms since the 1950s—is having a renaissance.
Jennings and other advocates of cloud seeding say their data show it can increase rain by 15% over a given area, compared with clouds that aren’t seeded. That is enough to bring an extra 2 inches of rain a year, water that can help crops survive a dry spell and recharge underground aquifers vital for farmers, ranchers and rural residents.
Across the Western U.S. and Mexico, demand for cloud-seeding has skyrocketed as increasing periods of extreme drought and a warming climate make it a cheaper alternative to big-ticket technological solutions such as the desalination of water piped inland from the Pacific Ocean or Gulf of Mexico. Cloud-seeding programs to boost both rain and snowfall are now under way in Texas, Utah, Colorado, Nevada, Idaho, New Mexico and California.
Arizona officials are considering two new programs. In Mexico, federal officials are seeding clouds across five Mexican states that have been suffering from an extended drought.
Cloud-seeding can work in the air or on the ground, where chimney-like generators send chemicals into air masses as they move up the side of mountains. Most cloud-seeding efforts use particles of silver iodide which have a crystal structure similar to ice. Once the chemicals are injected, the air temperature must reach 20 degrees Fahrenheit—then water vapor begins to freeze around the silver iodide, getting big enough to fall to the ground as either rain or snow.
In the summer, cloud-seeding firms use the water-attracting properties of salt crystals such as calcium chloride to do the same thing, except in warmer, humid clouds.
“In looking at the technology and the environmental impact, we came to the decision that it really was a safe and effective way of increasing local water supplies,” said Scott Griebling, water resources engineer for the St. Vrain and Left Hand Water Conservancy District in Longmont, Colo. “It was a no-brainer, especially in the long term.”
At the same time that local officials are embracing this weather modification technology, some weather experts question its effectiveness and whether it just pulls rainwater from one area to fall in another. They say conservation on the ground is a surer way to preserve scarce water supplies.
The World Meteorological Organization reviewed cloud-seeding programs across the globe in 2018 and concluded that cloud seeding is a promising technology but that the natural variability in each cloud system makes it difficult to quantify the difference seeding makes.
But local officials across the Western U.S. said it is a cost-effective way to increase both rain and snow. In Colorado, the St. Vrain water district spent $40,000 in 2022 for winter cloud seeding to increase snowfall and build up the snowpack in surrounding mountains. State officials kicked in another $90,000 to pay a cloud-seeding contractor.
In March, the U.S. Bureau of Reclamation announced a $2.4 million grant for states in the Upper Colorado River Basin to conduct aerial and ground-based cloud seeding.
In Utah, the state’s cloud-seeding program received a one-year, $12 million boost, while its annual budget increased from $800,000 to $5.8 million, according to Jake Serago, water resources engineer for the Utah Division of Water Resources.
Serago said historic low water levels in Great Salt Lake and Lake Powell, which supplies water to California, Arizona and Nevada, have piqued interest in cloud-seeding. “We’ve had a very long drought,” Serago said.
An experiment in Idaho found that winter cloud seeding using silver iodide produced the equivalent amount of snowfall to fill 300 Olympic-size swimming pools compared with clouds that hadn’t been seeded, according to a 2020 paper in the Proceedings of the National Academy of Sciences. The study used both radar and ground-based sensors to measure snowfall.
Sarah Tessendorf, an author of the study and project scientist at the National Center for Atmospheric Research in Boulder, Colo., said the environmental risks of cloud seeding are relatively benign since the amount of silver detected in the snow is below harmful levels.
“We’ve shown now that it can work,” Tessendorf said. “The key question we’re trying to figure out is under what conditions is cloud seeding most effective.”
For 73-year-old West Texas farmer Steve Williams, the benefits of occasional extra rainfall is worth the minimal amount he pays in taxes to his local water district that are earmarked for cloud seeding, about $20 a year.
Williams and his son, Ty Williams, farm 1,774 acres of cotton and wheat in Schleicher County, Texas, one of six counties covered by the aerial seeding flights from the West Texas Weather Modification Association in San Angelo.
Williams said he usually only gets one or two cloud-seeded rainfalls directly over his property each planting season. However the seeding drops rain on farms around him, recharging the underground aquifer that he and his neighbors depend on for irrigation and drinking water.
“It is a community effort,” Williams said. “Everybody benefits. If you happen to get under one of Jonathan’s clouds, you did pretty good.”
Back at the San Angelo airport, Jennings canceled flight operations after unstable air spawned three tornadoes and a dust storm that enveloped several nearby towns. The next day brought clear weather. A pilot loaded up the weather association’s single-engine Piper Comanche, climbed to about 5,000 feet, and crisscrossed Schleicher County before igniting more than two dozen seeding flares into the clouds.
Jennings said the resulting rainfall took about 20 minutes to form.
On the ground “there was rain all around us,” Williams said.
Write to Eric Niiler at eric.niiler@wsj.com