The practice has been around for decades, but cloud seeding has gone mainstream as a result of new technology and research showing its reliable, the Sacramento Bee reported Monday.
In a report this year, the California Department of Water Resources estimated cloud seeding projects generate 400,000 acre-feet of additional water supply annually in the state. That's about half the volume of Folsom Reservoir. An acre-foot is enough water to supply a typical household for a year.
"The message is starting to sink in that this is a cost-effective tool," said Jeff Tilley, director of weather modification at the Desert Research Institute in Reno, which practices cloud seeding in the Lake Tahoe Basin and Eastern Sierra Nevada. "The technology is better; we understand how to do cloud seeding much better. And because we know how to do it more effectively, it's definitely taken more seriously."
Cloud seeding involves spraying fine particles of silver iodide into a cloud system. Under the right conditions, the silver iodide causes water droplets in the clouds to form ice crystals that grow larger and turn into snowflakes. The goal is to increase the amount of precipitation that would otherwise fall.
Proponents say cloud seeding is cheaper than desalination, new dams and even conservation projects. Additionally, they say concerns about its environmental effects are unfounded.
More than a dozen California watersheds have cloud-seeding projects, many of which began running last week, the Bee reported.
The cloud-seeding push comes as the state goes through a dry spell. San Francisco's 3.95-inch rainfall total so far this year is the lowest precipitation total in the city between Jan. 1 and Nov. 7 since record keeping started 164 years ago, the San Francisco Chronicle reported.
Other parts of the state also have seen relatively little precipitation.