The original program was established to increase snow accumulation in the south and middle forks of the Payette River watershed. In 2008, Idaho Power expanded its cloud seeding efforts by enhancing an existing program operated by a coalition of counties and other stakeholders in the upper Snake River system above Milner Dam.
For the 2017-2018 winter season, the Central Mountains project (includes Payette, Boise, and Wood Basins) includes 30 remote-controlled, ground-based generators and two airplanes contracted for cloud seeding operations. The program in the Upper Snake River Basin includes 25 remote-controlled, ground-based generators operated by Idaho Power, 25 manual, ground-based generators operated by the coalition, and one airplane contracted for operations. Idaho Power provides meteorological data and weather forecasting to guide the coalition’s operations.
The principle of cloud seeding was discovered in 1946 by American chemist and meteorologist Vincent Schaefer. The use of silver iodide to enhance the formation of ice crystals in clouds was discovered only a few days later by noted atmospheric scientist Dr. Bernard Vonnegut.
The technology has been used since the late 1940s to enhance precipitation and also to dissipate fog and reduce the size of hailstones.
The latest data from the World Meteorological Organization, compiled in 2000, listed 74 projects ongoing in 23 countries worldwide. In 2001 the National Oceanic and Atmospheric Administration (NOAA) documented 66 projects conducted in the western U.S.
A wide range of entities sponsor cloud seeding programs in the U.S. They include municipal, county and state governments; irrigation, water resource and water conservation districts; airports; ski resorts; and private industry. (source: North American Weather Modification Council)
Active programs exist in several states, including Idaho, North Dakota, California, Texas, Colorado, Wyoming, Utah and Nevada.
Analyses conducted by Idaho Power since 2003 indicate the average annual snowpack in the Payette River Basin increased by about 12 percent since cloud seeding began in 2003. Idaho Power estimates cloud seeding in the Payette provides, on average, approximately 270,000 acre-feet of additional water for the Hells Canyon Complex and seeding in the Upper Snake provides (on average) over 420,000 acre-feet of additional water each year for all hydro projects downstream of Milner. Depending on runoff conditions, that additional water can generate approximately 850,000 megawatt-hours, or enough to power roughly more than 74,000 homes.
Studies conducted by the Desert Research Institute from 2003 to 2005 support the effectiveness of Idaho Power’s program.
Idaho Power seeds clouds by introducing additional ice nuclei (silver iodide) into winter storms. The additional ice nuclei increase precipitation from passing winter storm systems. If a storm has water vapor and appropriate temperatures, the conditions are optimal for cloud seeding to increase precipitation.
Idaho Power uses two methods to seed clouds: 1) ground generators at high elevations or 2) airplanes that release special flares into storm clouds. Either method successfully releases silver iodide into passing storms. Minute water particles within the clouds freeze on contact with the silver iodide particles and eventually grow and fall to the ground as snow.
Research indicates that there is no evidence that cloud seeding in one location causes a reduction in precipitation in neighboring areas. During a storm, a relatively small portion of the airborne water vapor falls to the ground as precipitation. Cloud seeding increases that amount slightly, leaving most of the water vapor still present in the storm system. The additional precipitation that does fall is not lost from the water cycle.
Typically, a well-run cloud seeding program would affect less than 1 percent of the water vapor in the atmosphere.
Idaho Power works closely with federal, state and local authorities to ensure our cloud seeding operations comply with all relevant environmental and land-use guidelines.
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