While Southern California finishes out a fifth year of drought, Hurricane Matthew dumped more than a foot of rain along some parts of the lower East Coast last week (send some of that water here, please).
On Oct. 4, the Santa Barbara County Board of Supervisors contemplated declaring an official disaster for Lake Cachuma because it’s 93 percent empty. Once it drops to roughly 6 percent, it becomes a “minimum pool,” the term used by officials to indicate that the water can no longer be used for human consumption.
At the same meeting, the supervisors approved a nearly $352,000 payment to North American Weather Consultants (NAWC), a Utah company, for a cloud-seeding program to induce rain clouds to dump their precious cargo over targeted areas of the county—namely Lake Cachuma and Twitchell Reservoir.
In use since 1981, the program is intended to be a cost-effective supplemental water supply for the drought-stricken county. Cloud seeding is one way to bring needed rainfall to specific areas. Tom Fayram, deputy director of the Santa Barbara County Public Works Department, which runs the cloud-seeding program, said that adjusting for inflation, the program costs the county more or less the same amount each year.
To spread the “seeds,” a twin-engine Piper airplane gets outfitted with racks holding burning flares that spray silver iodide into a cloud. Water condensation builds around the iodide particle, forming a raindrop.
Despite Lake Cachuma being at a record low, past cloud seeding has helped increase the amount of rainfall by as much as 21 percent at Cachuma and 9 percent at Twitchell, according to analyses performed by NAWC starting in 2013.
In the Tri-County area, only Santa Barbara County uses cloud seeding. SLO and Ventura counties do not.
The problem is that cloud seeding simply augments existing rain clouds, which have been mostly absent for the last five years. Predicting if and when rain clouds are coming can be a tricky business.
In order for seeding to be effective, Fayram said there needs to be a “multiple storm event.”
“You never know in any given year,” Fayram told the Sun. “It’s like timing the stock market. But that’s why we consistently run the program—to maximize the effort when the conditions are right.”
The so-called “Godzilla” El Niño predicted by meteorologists, including Bill Patzert, a climatologist for the NASA Jet Propulsion Laboratory in Pasadena, turned out to mostly be a dud—at least for thirsty Southern Californians who hoped it would be the answer to the drought.
Patzert told the Sun that he considers cloud seeding to be a measure of last resort. He said he generally agrees that it works, but he questions if it’s really worth the cost.
“It works,” he said, adding that he’s never heard of a region where cloud seeding increased rainfall enough to impact a drought. “The question is how well? Especially in the semi-arid climate that we live in. How much punch do you get for your buck?”
Patzert added that in the American West, which tends to be dry, the conditions are ripe for the cloud-seeding industry. There are cases where seeding has, perhaps, worked too well and was blamed for mayhem caused by flooding.
Following the torrential rains of 1996-97, residents of Lathrop, Calif., sued the Modesto and Turlock irrigation districts and the city of San Francisco for what they believed was flood damage caused by cloud seeding.
As reported in the Stockton Record, residents who filed suit said that there wasn’t enough reservoir space to accommodate the runoff and that irrigation districts failed to release water in anticipation of the flood from the rain, causing multiple levees to burst.
According to a 2007 report issued by the California Department of Water Resources, the flooding inundated at least 300 square miles of the Central Valley, caused nearly $2 billion in damages, displaced hundreds of thousands of residents, and killed nine people.
And there are questions about whether cloud seeding is counter-productive in other ways. Experts, including NASA’s Patzert, say it’s possible that seeding could prevent clouds from producing rain in other areas where it would’ve normally rained had it not been for seeding.
“That’s an impossible conclusion to reach,” Fayram said. “Studies have shown that there’s so much water and energy in a storm that it’s practically immeasurable.”
Patzert maintains that such interventions might not be a worthwhile investment.
“Scientifically, it works,” he said. “But the [positive] impacts are so minor that it’s not worth the cost.”
Staff Writer David Minsky can be reached at dminsky@santamariasun.com.
This article appears in Oct 13-20, 2016.