Cloud seeding remains a controversial cure
In 2003 the National Research Council issued a lengthy report that found “no convincing scientific proof of the efficacy of intentional weather modification efforts.”That was the first sentence. The second paragraph, however, reported an exception to this sweeping generalization: “strong suggestions” that cloud-seeding in winter – as opposed to summer – works in mountainous areas.Finally, 90 pages later in the appendix, the report explained the basis for the silver lining amid otherwise dark clouds of pessimism: experiments conducted in the 1960s near the Climax Mine, between Leadville and what is now Copper Mountain.Now, even as spring runoff thunders toward Lake Powell and other reservoirs, states in the parched American Southwest are looking more intently at cloud-seeding, wondering if it can forestall the hardest choices of scarcity in the coming years that many climate scientists predict will be hotter and drier.Cloud-seeding is among several augmentation and conservation strategies being examined. Others include expanded desalinization efforts, use of excess water from coal-bed methane mining, and removal of thirsty salt-water cedar, also called tamarisk, from creeks and rivers.”People aren’t going to stop moving to the West, and if we can proactively get additional water out of the Colorado River, it might certainly prevent some problems in the future,” says Kay Brothers, deputy general manager of the Southern Nevada Water Authority.Her district is launching a study that intends to examine the various augmentation strategies.”The goal is to put all of them on a level playing field and get an idea of the costs, how much water could be yielded, and some of the environmental issues,” she says.
Cloud-seeding appears to be among the most low-hanging among these augmentation strategies.The basic process was discovered in 1946 by engineers at the General Electric laboratory in Schenectady, N.Y. Dry ice shavings, they found, could be used to induce formation of rain – or snow. By 1949, the federal government had launched experiments in New Mexico. That federal research budget expanded after a major drought in the mid-1950s. Among the atmospheric scientists benefiting from this federal largesse was Lew Grant, then a professor at Colorado State University.Grant conducted the experiments from Chalk Mountain, overlooking Fremont Pass. Those experiments yielded the conclusion that cloud-seeding could increase precipitation from some winter storms by 10 percent to 15 percent.The key to the credibility of those experiments was randomization. In other words, thanks to the federal funding, Grant and his graduate students – who later spread out across the West, nearly all missionaries of cloud-seeding – were able to seed some clouds, but not others, in ways to eliminate prejudice from the choices.Grant also supervised less extensive experiments in the San Juan Mountains and, in the late 1970s, near Steamboat Springs.Meanwhile, another drought in 1976-77 came along that caused ski areas, water districts and others to hurriedly summon cloud-seeders. Vail Associates, as the precursor to Vail Resorts was called, began cloud-seeding and hasn’t quit it yet – one of the longest- continuously-operating cloud-seeding programs in the West. Local towns helped pay for the cloud-seeding.However, in this and other cloud-seeding programs, the work was aimed at snow, not just vigorous scientific proof of snow. And even those were mostly suspended when big-water years returned. In 1983, unexpected high runoff almost washed away Glen Canyon Dam. About the same time, the federal government largely abandoned weather-modification efforts.
Cloud-seeding has remained in the shadows of scientific respectability. Like the family Bible, it is something most frequently summoned in times of crisis.The drought year 2002 was one of those pivotal times. Desperate for snow, farmers and ranchers, municipal utilities, and water districts again reached for their wallets. Whatever the cause, a good snow year followed. One rancher in Colorado’s Gunnison County probably spoke for many last fall when he hesitatingly agreed to help pay $92,500 for another winter of artificially inseminating the sky in the Crested Butte area. “I don’t know if it works or not,” said the rancher, “but I’m afraid to not fund it and then find out it had been what gave us our snow.”Meanwhile, several efforts to further explore when and how cloud-seeding works are being made. U.S. Rep. Mark Udall, a Democrat whose district includes the I-70 corridor, last year introduced a bill in conjunction with U.S. Senator Kay Bailey Hutchison, Republican from Texas, that would create a Weather Modification Advisory and Research Board to oversee disbursement of $10 million annually for the next decade.Some of the thinking behind the proposal is that while the states pay for cloud seeding intended to produce snow, the federal government should oversee the purer science, such as experiments. The greatest uncertainties, scientists say, have to do with timing of seeding relative to cloud systems and the precision of targeting.”Weather modification is not some kind of weird science,” insists Udall’s press secretary, Lawrence Pacheco. But more fundamental research is needed to understand and improve weather-modification technologies, he says.Among those planning fundamental research is Wyoming, where legislators appropriated $8.8 million for what may be the most scientifically rigorous study ever. A five-year double-blind experiment is being planned for in the Medicine Bow Range near Laramie. There will be placebo particles in some generators, the real stuff (silver iodide is the most common agent) in others. Effects of seeding storms will be predicted, and then measured for effectiveness.Computer modeling – a major advancement in weather modification – enables precision.The goal is to “try to pull out a signal from the natural range of variability,” says Dan Breed, an atmospheric scientist with the National Center for Atmospheric Research, which has been retained to structure the experiment.Doing so is virtually impossible in one season, given the almost infinite range of possibilities within clouds, he says. “Wyoming is a little bit on the leading edge of doing this in a well-measured way,” he says.
Already a believer is Larry Dozier, deputy general manager for the Central Arizona Project. He says cloud-seeding would require little infrastructure other than scattered ground-based generators and perhaps some airplane operations. Some estimates place the cost at $5 to $10 per acre-foot of water produced.Dozier calculates that same acre-foot of water produced in the mountains of Colorado, Utah, or Wyoming could be used to produce $60 to $80 worth of electricity at Glen Canyon, Hoover, and other dams. Altogether, he believes cloud-seeding could augment the river basin yield 7 percent to 10 percent per year. But few others see it as a silver bullet. Glenwood springs-based Jim Lochead, who represents several major Colorado water users in Colorado River negotiations, says he is waiting to see firmer science. Still, even small gains in water would be huge. “If it produces perhaps 1 percent more water, that’s a big amount,” he says.The more arid states of the West have long talked about augmentation strategies. In the past – although not this time – there have been talk of trying to draw water from the Columbia River to the Southwest.And, even two years ago, Colorado state officials talked about cutting trees in the national forest, so more water would come off the national forests. That technique, called vegetative management, is not being considered in this new, broader study.Among those skeptical of the latest initiative is Doug Kinney, a research associate at the University of Colorado’s Natural Resource Law Center.”Desalinization and cloud-seeding are great examples of these ideas that never go away,” he says. “There’s nothing wrong with looking at them every time, but they just rarely measure up as the best solution.”Like many environmental activists, Kinney believes water conservation always emerges as the best way to gain “more” water. The experience of the last several years suggests they’re at least partly right.The drought, for example, has produced new water-saving habits among the 1.2 million consumers of Denver’s existing water supply. Denver Water now figures it can meet the needs of 1.9 million people by mid-century, with 37 percent of that increased supply being realized by conservation and system efficiencies, says Greg Fisher, the agency’s chief demand-side planner. Before, the answer to growing demand was usually increased supply.
Environmentalists also foresee more transfers of water from farms to cities. Of Central Arizona Project water, half goes to agriculture. In some states, the rate is significantly higher, with much of the water used to produce livestock. That freedom to respond to market forces “could provide a vast amount of water at really very little impact to agriculture in the American Southwest,” believes Jennifer Pitt, senior resource analysis with Environmental Defense.Chris Treese, the director of legislative affairs for the Glenwood Springs-based Colorado River Water Conservation District, says the discussions of both water scarcity and water-augmentation strategies would have happened anyway. The drought of 2002 only hastened them.Cloud-seeding is an example of “how creative we can be, and how cost-effective we need to be,” says Treese. “We need to look at all the answers possible,” he says. “None of them is a silver bullet, and it will take a multi-state, multi-focused approach to resolving water supply issues.”Vail Daily, Vail, Colorado