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SLO County leaders test cloud seeding to raise Lopez Lake Reservoir levels

Posted at 5:41 PM, Jan 02, 2020

We might not be able to create weather, but there are ways to enhance it.

The San Luis Obispo County Board of Supervisors recently approved a winter cloud seeding project that could add millions of gallons of water to the Lopez Lake Reservoir and supply thousands of homes.

Cloud seeding has been used for decades around the world. It's a process in which silver iodide is released by ground dispensers or planes. The silver iodide then reacts with a rain-producing cloud to form more and larger ice crystals. The ice crystals then fall and melt on their way down to make rain.

cloud seeding

Even though California has been drought-free since March of 2019, some Five Cities residents who get water from the reservoir say more is needed.

"I think everybody here is trying to be compliant and make their yards drought tolerant and not over water and be conscious of the environment and what it takes to be conservative," said Terri Hopson. "It's something everybody has to keep in mind, especially on the West Coast."

Imagine 3,000 acre feet or 326,000 football fields each covered in an inch of water -- that's how much water the county hopes to produce with the project.

"What that means is a 6% increase in lake capacity, but the important number is 3,000 acre feet because it would supply 6,000 homes with water," said Ray Dienzo, Supervising Engineer of Water Resources for San Luis Obispo County.

Santa Barbara County has been using cloud seeding since 1981 and has seen an increase of 10-20% in rainfall over targeted areas; however, there are studies that question the effectiveness of the method.

There is a concern the seeding agent, silver iodide, is toxic in large amounts but some studies show there is no significant environmental impact with the amount used for cloud seeding.

The nearly $235,000 project covers the 2020 winter season and is paid for with the overall Zone 3 budget.