From the pages of
Sublette Examiner
Volume 4, Number 22 - August 26, 2004
brought to you online by Pinedale Online

Cloud seeding contemplated

by Cat Urbigkit

The Wyoming Water Development Commission has hired a consulting firm to conduct a level II feasibility study for weather modification in the Wind River and Sierra Madre mountains.

At a scarcely attended public meeting last week in Pinedale, Leah Bratton, a senior analyst with the Wyoming State Engineer's Office, explained that Wyoming has claimed sovereignty for resources within its borders, including the atmosphere. That means that anyone wanting to conduct a weather-modification project must first seek a permit from the State Engineer's Office. The $50 permits are for one-year terms and are revocable.

Cloud seeding is a form of weather modification that assists nature in forming precipitation by providing droplet-forming nuclei at opportune times and places. Most often, ground generators are used to place silver iodide into the air to produce the nuclei, but airplanes are sometimes used in cloud seeding.

WWDC's Barry Lawrence gave some weather-modification history, explaining that the first permit for cloud seeding in Wyoming was granted in 1951 for a project in eastern Wyoming. Since then, there have been annual permits granted for weather modification projects . There are currently 85 permits, with goals ranging from increasing snowpack and recharging aquifers to reducing hail damage.

The longest-running cloud-seeding project in Wyoming involves the Eden Valley Irrigation District's turnkey operational program in place today. The district has five ground-based cloud-seeding units. Three are silver iodide generators set along Highway 191 at mile markers 55, 65 and 75. Two units are propane burners located along Muddy Ridge that are remotely operated out of Provo, Utah. Lawrence said the irrigation district claims to have seen an 11 to 13 percent increase in winter snowpack due to seeding.

Utah's cloud-seeding program involved 130 ground-based generators in 2003, at a cost of $336,000. Lawrence said Utah estimates it has experienced a 5 to 20 percent increase in April snow water content, translating to an annual increase in runoff of 250,000 acre feet of water.

Lawrence said that Wyoming officials have received numerous inquiries into a more intensive cloud-seeding program, and the result of the increased interest is funding from the Wyoming Legislature for the six-month feasibility study just undertaken.

Weather Modification, Inc., of Fargo, N.D., will study the feasibility of cloud seeding in the Wind Rivers. Project tasks include reviewing previous research, examining climatology of area, developing project design, addressing environmental consequences and conducting a cost/benefit analysis.

The study will provide an assessment of airborne- and ground-based seeding, and will provide quantifiable estimates of the amount of snowpack likely to be produced and how the increases will likely relate to streamflows. The report and executive summaries are to be completed by mid- to late-September, with project presentations and public meetings in October.

Weather Modification's Bruce Boe said that anticipated challenges include the public receptiveness to the proposal, since common concerns include seeding agent safety (although an inert agent is used), concerns of the consequences of too much snow (such as road closures), questions as to whether it is morally right to seed clouds, and concerns that if one location is seeded, does it reduce precipitation in other areas.

If the final Wind River weather modification project design is approved and undertaken as an active weather-modification project, the project wouldn't begin until the fall of 2005.

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