Enhancing our water supply

Utah has been cloud seeding since the early 1950s to help augment the state’s water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud.

This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions.

Why is the state of Utah involved in cloud seeding?

Since snowpack is Utah’s largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn’t work just anywhere. The conditions have to be right. Luckily, Utah’s topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost between $10 -$15 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. 

Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah’s cloud seeding takes place only in the winter. There is insufficient local support for a summer seeding program and Utah’s semi-arid climate doesn’t present the right conditions to generate enough precipitation. (Summer months are often too dry and don’t have enough clouds.) In 2023, the Utah Legislature allocated $12 million in one-time funding and provided an annual budget of $5 million to the division. Costs for cloud seeding programs are split with local sponsors. 

Questions?

Contact: Jonathan Jennings at jjennings@utah.gov

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