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Wyoming project could spark support for could seeding

Isaac Brambila
ibrambila@tahoedailytribune.com
The Tahoe-Truckee area is one of 15 areas in California where cloud seeding projects are taking place.
Isaac Brambila/Tahoe Daily Tribune |

A $13 million cloud seeding project conducted in Wyoming that revealed an increase of a much as 15 percent of annual mountain snowfall could encourage California water authorities to expand its own operations to combat water shortage in the state.

The final results will be submitted to scientific journals for review.

According to Maury Roos, Chief Hydrologist for the California Department of Water Resources (DWR), the DWR will likely wait until the information is final before making decisions regarding any further support given to cloud seeding projects in California.



The DWR, in the California Water Plan Update 2013, presents cloud seeding, or precipitation enhancement, as an option to help combat the effects of the ongoing drought.

Roos said it is still early to get overly optimistic, but the data from the project seems to suggest researchers arrived at positive results. He added that there has been a research in the past, but that the results have not been conclusive.



Cloud seeding works by artificially stimulating clouds to produce more rainfall or snowfall than they would produce naturally. Cloud seeding injects substances, typically silver iodide, into the clouds that enable snowflakes and raindrops to form more easily.

Occasionally, other agents, such as liquid propane, have been used, according to a precipitation enhancement report. In recent years, some projects have used hygroscopic materials – substances that take up water from the air – as supplemental seeding agents.

In their study, which went on for approximately 10 years and was funded by the state of Wyoming, researchers found increased snowpack produced more water in nearby rivers and streams, according to an AP report. They used ground-based seeding generators on the Wind River, Sierra Madre and Medicine Bow Mountain ranges. National Center for Atmospheric Research scientists, working independently, analyzed the data and found that snowpack was not affected outside of the immediate area of the cloud-seeding operations.

Winter orographic cloud seeding, which involves cloud seeding where wind blows over a mountain range and causes clouds and rain or snow by lifting the air, has been practiced in California since the early 1950s, according to the Precipitation Enhancement Report. Most of the projects are along the central and southern Sierra Nevada.

In 2011, there were weather modification projects in at least 15 areas, including the Tahoe-Truckee area.

According to the report, all precipitation enhancement projects are intended to increase water supply or hydroelectric power.

A new estimate made for Update 2013 by the DWR, the report states, revealed that the combined California precipitation enhancement projects, on average, generate about 400,000 acre-feet of runoff annually, which would be an average of about a 4 percent increase in runoff. Costs for cloud seeding generally would be less than $30 per acre-foot of water supply each year.

The report estimates that about $3 million to $5 million is being spent on yearly operations. Realizing the additional 300,000 to 400,000 acre-feet of potential new supply could require an initial investment of around $8 million for planning, reports and initial equipment, in addition to about $6 million in annual operations costs. During the next 25 years, that would add up to about $150 million, which would be nearly $22 per acre-foot of water supply.

Among potential deterrents, the report lists issues brought to the DWR such as a lack of concrete information, challenges with operational and executional precision and unintended impacts, such as long-term toxic effects of silver.

However, the report states that the potential for eventual toxic effects of silver has not been shown to be a problem, as silver and silver compounds have been found to have low toxicity levels.

Still, though the conclusion of the report supports cloud seeding operations, the results of Wyoming project may have an effect regarding the amount of resources allocated to the current projects.

“It’s significant that they do seem to find positive results,” Roos said.


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