June 28, 2015--Can cloud-seeding ride to the rescue? (Mountain Town News)

After a so-so winter, the snow piled up through May in the mountains of Colorado, taking the edge off drought. This takes the edge off of the big Colorado River reservoirs, Lake Mead and Lake Powell. But the overarching story at those reservoirs since 1999 has been of decline, even after a few big years. In the last several years, there has been increasing talk about the potential for the two reservoirs to become empty. Las Vegas, reliant upon Lake Mead for most of its water, isn’t just talking about the possibility. It is nigh-on to completing a third tunnel into the reservoir, this one at a cost of $817 million and, unlike the others, at the very bottom of the reservoir, in case there’s nothing left of Lake Mead except for the Colorado River. That’s how dire Las Vegas, operating as the Southern Nevada Water Authority, takes this potential of long-term drought. Eric Kuhn, the manager of the Colorado River Water Conservation District, spoke to the implications of this continuing drought at a forum in Colorado’s Summit County this spring. “Bad things happen when Lake Mead and Lake Powell get drained,” he said in an event covered by the Summit Daily News. He described the draining of Lake Mead as a distinct possibility in the next few years.

What about building a pipeline to the Mississippi River or some other water-rich location? “To expect that we can export our problems to somebody else, I just don’t see that somebody else will willingly accept them,” he said. How about just making some more water? That effort began soon after World War II in different times of drought. Scientists at General Electric in New York state had discovered the general principle. And in some places of the West, cloud-seeding has occurred since the 1950s – including, at Vail Mountain, since 1978. But does it work? Since the federal government yanked research dollars from cloud-seeding experiments in the 1980s, relatively little rigorous science had been conducted. Instead, there were the claims of commercial-cloud seeders, who predicted gains of 10 to 15 percent—as long as they had clouds to work with.

In 2004, Wyoming set out to fill that gap. An experiment that ultimately cost $14 million was designed by scientists working for a federal laboratory, the National Center for Atmospheric Research. Parallel mountain ranges southwest of Laramie, just north of the Colorado border, constituted the Wyoming laboratory. Propane was burned to loft silver iodide from ground-based generators into the clouds passing over the Sierra Nevada and Medicine Bow ranges. In the experiment, 154 storms during six winters had the temperatures needed for effective seeding, but only 118 had the moisture content. And of those, 18 were tossed out because of contamination problems.

Last December, at a meeting room in Cheyenne, scientists delivered the results. It took a full afternoon and the results were sometimes confusing. But hydrologists and meteorologists who listened to the proceedings remotely told me they had no trouble hearing the key statistics: just a 3 percent increase in precipitation but with the 28 percent probability that cloud-seeding had nothing to do with the increase. Only by creating models were researchers able to make a case that snowfall had been augmented 5 to 15 percent. To view the full article visit the Mountain Town News.