Bristling with what appear to be fireworks aimed at the sky, a remote mountain ridge south of Santa Maria looks set for a pyrotechnic celebration. But this is more of a rain dance, of sorts.
This is one of a network of Santa Barbara County mountaintop sites used to launch a rainmaking chemical into storm clouds. The idea is to augment local water supplies using a technique called cloud seeding.
Successful tests on local storm clouds conducted by the U.S. military in the 1960s and ’70s were used for a more sinister purpose, however: warfare. American forces carried out secret aerial cloud-seeding operations designed to wash out the Ho Chi Minh Trail with heavy monsoon rains in North Vietnam, from 1967 until 1972. Cloud seeding as a weapon of war was later banned by international treaty.
Santa Barbara County Water Agency has been seeding local clouds with silver iodide nearly every winter since 1981, both from mountaintop stations and from airplanes. The chemical makes water droplets in clouds artificially condense into ice that falls as rain. The rain then flows into local reservoirs—or so the theory goes.
“Cloud seeding can be controversial,” Dennis Gibbs, senior hydrologist with the county water agency, told the Sun.
The scientific community is “still somewhat divided” on the effectiveness of “weather modification,” county supervisors were told in a report last October before they approved last winter’s $310,000-cloud-seeding program.
Proving conclusively that the silver iodide seeding technique actually produces more precipitation than would otherwise have fallen downwind is a challenge, according to the report to supervisors by cloud-seeding contractors North American Weather Consultants.
Mountainous regions like the ones in Santa Barbara County are considered the best bets for success. And a naval weapons laboratory’s research results from decades ago, known as “Santa Barbara II,” concluded that precipitation was increased over a large area from ground-based silver iodide flares like the ones on Harris Grade, and from airplane wingtip silver iodide generators.
“The Santa Barbara program has an interesting background,” North American Weather Consultants president Don Griffith said in a phone interview from his Sandy, Utah office.
“Santa Barbara [County] was a trial for some of the technologies they were developing,” Griffith said.
Those technologies are still the basis for the county water agency’s ongoing cloud-seeding program. Jointly funded by local water districts and the county, the program aims to add more storm runoff to Twitchell Reservoir, Cachuma Lake, and Gibraltar Reservoir. Normally, silver iodide is dispersed into storm clouds from aircraft and from sites at Harris Grade, Mt. Lospe, Sudden Peak, West Camino Cielo, Gibraltar Road, and Gaviota Pass.
For this coming winter, though, some water agencies are opting out, with reservoirs already brimming. That will likely mean a reduced cloud-seeding operation designed to help keep Twitchell Reservoir full using only flares fired from the ground rather than from aircraft. The estimated cost is $120,000, Gibbs said. Water would be gradually released from Twitchell Dam to help recharge the Santa Maria groundwater basin, he explained.
Silver-iodide flares known as AHOGS—for automated high-output ground-based seeding—will be remotely detonated by computers in North American Weather Consultants’ offices in Utah using a cellphone Internet connection. Timing of the firing is guided by weather information computers receive from NEXRAD radar stations at Vandenberg Air Force Base and in the Ojai area.
Predicting a 10 to 15 percent increase in rainfall in the Twitchell Reservoir watershed—which also includes the Huasna Valley in southern San Luis Obispo County—after cloud seeding, Gibbs said, “It’s the cheapest source of water. We’re not taking anybody else’s rain. We’re giving nature a helping hand.”
That wasn’t the way cloud seeding was seen during the Vietnam War, after research conducted in Santa Barbara County by the Naval Ordinance Laboratory in China Lake, Calif.—along with its contractor North American Weather Consultants—was applied to weather warfare against the North Vietnamese from 1967 to 1972.
“We regard the weather as a weapon,” weapons lab admiral Pier Saint-Amand told the U.S. Senate in 1972, once the secret cloud-seeding missions became public—and were discontinued—after reports in the Washington Post and The New York Times.
At the time, Sen. Claiborne Pell, chairman of the Senate Foreign Relations Committee, said, “Rainmaking as a weapon of war can only lead to the development of vastly more dangerous environmental techniques whose consequences may be unknown and may cause irreparable damage to our global environment. This is why the United States must move quickly to ban all environmental or geophysical modification techniques from the arsenals of war.”
An international treaty prohibiting weather warfare, the Environmental Modification Convention, came into force in 1978.
These days, it’s the overall management of the planet’s atmospheric water resources that’s a controversial issue surrounding cloud seeding operations now being carried out in about 40 countries. At a recent San Luis Obispo County Board of Supervisors meeting where the local cloud seeding program came up in the public comment period—the program targets storm clouds in southern SLO County as well as northern SB County—activist Eric Greening said, “I think the whole issue needs study and maybe a big slowdown. Our involuntary and still uncontrolled effects on the climate are bad enough without deliberately trying to change the climate too.”
Contributing writer Kathy Johnston can be reached at kjohnston@newtimesslo.com.
This article appears in Sep 29 – Oct 6, 2011.