State and federal policy trends, DRI science: cloud seeding presentation before Nevada interim natural-resources committee

The joint interim standing committee on natural resources heard two technical presentations on cloud seeding and related legislation, with speakers saying the practice is widely used in Western states and can be a cost-effective tool to augment mountain snowpack.

Tom Klein of the National Conference of State Legislatures told the committee that state-level activity on weather modification has grown. He said several Western states have enacted supportive measures—often appropriations that fund existing programs—while other states have introduced prohibitions. “Colorado, New Mexico, Utah, Idaho, Nevada, Washington and Wyoming” were cited as states that have passed legislation supporting cloud seeding, he said, and he noted Florida adopted a prohibition in 2023. Klein said most supportive measures take the form of appropriations or authorizations rather than broad regulatory frameworks, and that some newly introduced bills center on constituent concerns about intentional atmospheric activity.

Frank McDonough, research scientist at the Desert Research Institute and manager of Nevada’s cloud-seeding program, described Nevada’s long-running, ground-based program and the science behind it. He said cloud seeding in Nevada uses microscopic silver iodide particles released into subfreezing liquid-water clouds to nucleate ice crystals and increase snowfall. McDonough told the committee the state program is entirely ground-operated (no aircraft), operates under real-time meteorological supervision and suspension criteria (including flood and avalanche watches), and uses generators sited in climatologically favored locations such as the Santa Rosa Mountains (Humboldt County), the Ruby Mountains (Elko County), the Spring Mountains (Nye/Clark border) and the Tahoe–Truckee watershed (Washoe County).

On effectiveness and scale, McDonough cited peer-reviewed studies and the state’s operational results: cloud seeding can increase snowfall by up to about 15% in suitable storms and has been associated with average streamflow increases on the order of 8% in some studies. He reported that a robust, fully operational program can produce 40,000-plus acre-feet in some years and that the 2023–24 season produced roughly 56,000 acre-feet; he also said the program’s infrastructure investment is roughly $2.5 million and that recent cost estimates have been on the order of $10–$15 per acre-foot of additional water.

McDonough addressed safety questions about silver iodide, saying the compound used in cloud seeding is an insoluble, particulate form that does not disassociate into bioavailable silver ions; he cited long-term environmental studies showing no detectable accumulation from multi-decade seeding programs. The program manager also said studies and monitoring are used for validation and that runoff and recharge behavior are complex—snow on the ground is not the same as immediately usable groundwater.

Committee members asked for additional detail on county-level activity, measurement and validation techniques, and whether inadvertent cloud-seeding effects (for example from industrial aerosols or contrails) are being studied; McDonough and Klein said they would provide references and follow-up materials. The committee’s staff brief that preceded these presentations (Legislative Counsel Bureau Research Division) and the DRI materials were cited as available resources.

The committee did not take formal action on policy at the meeting; members asked staff to circulate additional citations and validation studies and discussed further briefings at future interim meetings.