Sacramento Municipal Utility District to expand cloud seeding in El Doardo County

Dawn Hodson
Mountain Democrat
This map shows the area where cloud seeding operations currently take place, as well as the proposed expanded area.
Courtesy SMUD |

Wanting to amp up both its power and water generation, the Sacramento Municipal Utility District is making plans to more than double the area where it cloud seeds this year.

Currently SMUD seeds more than 190 square miles within Placer and El Dorado County with silver iodide.

If it’s expanded plans are approved, SMUD will seed an additional 444 square miles primarily south and west of where it’s already seeding in El Dorado County along with a small portion of Amador and Alpine counties.

To answer questions about the project and as part of the California Environmental Quality Act review process, on June 1 the district held a public workshop in Strawberry.

A small contingent of SMUD employees and about 15 members of the public attended as SMUD civil engineer Dudley McFadden took the lead in walking people through the project and answering questions.

Noting the reason for expanding the program, McFadden said, “When we generate more hydro power and water, it benefits everyone in the region,” adding that the expanded seeding is expected to add 3 to 7 percent more rainfall.

However, not everyone was convinced with some people expressing concern about the long-term effects of cloud seeding and how the material might build up over time in the soil, vegetation and water.

Flint Morgan, who lives in Camino and is a self-described avid outdoorsman, said the Environmental Protection Agency classifies silver iodide as a hazardous substance that is highly toxic to fish, livestock and humans. He also expressed doubts about the effectiveness of cloud seeding or how it benefits the environment.

Daphne Osell, a resident of Twin Bridges, expressed the same concerns in addition to seeing the extra rain and snow as a threat to people who live in the area. She mentioned people being trapped in their homes this past winter because of all the heavy snow and wanted to know if the county planned to provide additional services to them in the case of a medical emergency.

Arguing the other side of the issue was Frank McDonough, a visiting meteorologist who works for the Desert Research Institute in Reno.

Citing a large study recently completed in Wyoming, McDonough said researchers found only four to six parts per trillion of silver iodide in snow that had not been seeded and 10 to 20 parts per trillion of silver iodide in snow that had been seeded.

Results, according to him, that suggested any leftover silver iodine is too diluted to have any accumulative effects.

Cloud seeding for almost half a century

Emphasizing its long history of cloud seeding, McFadden said SMUD has been doing so since 1968 and before that helped with experiments being carried out by other agencies working to increase rainfall.

At the same time he admitted they don’t monitor its effect on the environment.

McFadden said they don’t do so for several reasons: one is silver iodine is a non-reactive agent, second it’s not bio-accumulative according to the studies he’s read and third because it’s found in such trace amounts, it’s almost undetectable.

“We’d love to be able to find it in the snow because it would justify the program, but in studies elsewhere, they only find it in parts per trillion,” he said. “We just don’t have the resources to do science so we leave it to other agencies to do.”

McFadden said up until 2007 SMUD employees did the cloud seeding but since then they have contracted the work out.

This past winter they spent $200,000 on cloud seeding but the agency has spent as much as $280,000 in past year’s efforts.

Various methods are available to get the job done including ground-based flare trees, mobile units, or specialized aircraft that disperse seed clouds with precipitation forming particles made of silver iodide. Ice crystals then form around the particles and grow into snowflakes.

Cloud seeding doesn’t make weather and can only be used during cold storms that produce snow. McFadden said on average cloud seeding produces 3 to 7 percent more hydroelectric power.

McFadden said they expect to take the draft CEQA report to SMUD’s board in October in order to get approval to start the enhanced project.

If the board approves it, they will seed the entire 444 square miles as weather permits. Otherwise, they will continue seeding the 190 square miles as they’ve done in the past.

People can review and comment on the draft CEQA report at

All public comments are due by June 16 at 5 p.m. Comments can be emailed to Jerry Park, who is the CEQA project manager, at Or they can be emailed to McFadden at

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