BOISE — Because of the extraordinary amount of snow that fell across the Western U.S. this winter, most people probably didn’t see cloud seeding efforts to boost snowpack as critical.
But the importance and efficacy of cloud seeding were a main topic of discussion April 17-20 during a joint meeting of the Western Snow Conference and the Weather Modification Association.
During a related event held for the public, North American Weather Consultants Meteorologist Todd Flanagan explained to why cloud seeding is necessary most years in the arid West.
“We want to increase snowpack in mountain areas,” he said. That means more storage water in reservoirs and “obviously that means an increased water supply for regions that depend on snow melt to get their water.”
Flanagan said that since modern cloud seeding efforts started almost six decades ago, research indicates that it works. Substances such as silver iodide are sprayed into the air, causing ice crystals to form at higher temperatures and fall as snow. Several cloud seeding programs have reported 5-15 percent increases in snowpack levels, he said.
Idaho Power meteorologist Derek Blestrud told Capital Press that an analysis of the company’s cloud seeding efforts in Idaho’s Payette River Basin demonstrated an average annual 14 percent increase in precipitation since 2003.
That equates to about an additional 270,000 acre-feet of water every year, he said.
“That’s very valuable for irrigators, for the power company and for everybody else,” he said.
Blestrud said cloud seeding efforts are likely to expand in the West as demand for water increases.
Idaho Power’s two main target areas for cloud seeding are the West Central Mountains, which include the Payette, Boise and Wood basins, and the upper Snake River Basin, which provides storage water for a much of southern Idaho.
Idaho Power uses 55 ground-based generators and three aircraft in its cloud seeding efforts. The company plants to continue to build out in those regions, Blestrud said. In the future, that could mean a total of 80 ground-based generators and possibly a fourth aircraft.
Flanagan and Blestrud said research shows that cloud seeding doesn’t rob areas downwind of moisture.
According to analyses by North American Weather Consultants, several cloud seeding projects have shown small percentage increases in precipitation as far as 100 miles away.
“You’re not robbing Peter to pay Paul,” Flanagan said of cloud seeding. “You’re paying Paul and Peter gets a freebie.”