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Idaho Power adds about 100-million acre feet of water a year with the technology

PHOTO COURTESY IDAHO POWER - Cloud seeding adds silver iodide to clouds either by airplanes or ground devices release the chemical into the air. Idaho Power has used cloud seeding to produce more water for its hydroelectric plants since 2003 with much success.

The utility owns and operates 17 hydroelectric plants on the Snake River in Southern Idaho and its tributaries.

Idaho Power's cloud-seeding program seeds only a small portion of the 69,200 square-mile drainage area that feeds the Snake River upstream from Weiser, Idaho.

Shaun Parkinson, Idaho Power's cloud seeding leader, estimates on average cloud seeding produces one million acre-feet of additional runoff in the Snake River Watershed per year for the utility, or roughly five Wickiup Reservoirs full of water.

But to quote the legal disclaimer on many advertising claims: your results may vary.

How does cloud seeding work?

The "seeds" are silver iodide. Added to the super-cooled water in clouds, either by airplane or released from the ground, the silver iodide coaxes little drops of water to grow large enough to fall as snow or rain.

The conditions need to be just right for cloud seeding to work. Senior Atmospheric Scientist Mel Kunkel likens the conditions to Goldilocks. The water can't be too warm or too cold, it has to be just right. The elevation can't be too high or too low, it has to be just right.

Some years yield more precipitation than others.

"Our programs target the highest elevations," where moisture stays frozen longer, said Parkinson. "The snowpack at high elevations is another reservoir."

Idaho Power dedicates four scientists to all their weather forecasting needs, including cloud seeding, and a field team of six focuses predominately on cloud seeding.

Is it worth the investment?

Cloud seeding pays off for Idaho Power. Parkinson said, "Cloud seeding depends on the opportunities Mother Nature provides."

The process doesn't create more storms, but it can make the storms produce more precipitation.

Parkinson says the cost-benefit ratio generally ranges from 2.5-4 to 1, depending on the year, meaning each dollar invested brings $2.50-$4 to the company's hydroelectric system. That does not consider the additional value to irrigation, recreation, fisheries, and water quality.

The benefits extend beyond generating power. Additional water improves reliability of storage and natural flow for irrigation.

"In general, more water in a watershed improves water quality," said Parkinson.

More water recharges aquifers, improves fisheries and recreation with more water in reservoirs and rivers.

Myths about cloud seeding.

Cloud seeding does not reduce precipitation for nearby watersheds.

"The atmosphere is a continuous tap of water," said Kunkel. "As that system moves through the area (cloud seeding) encourages it to produce a little more than it normally would."

Kunkel says studies have shown cloud seeding in one area has a neutral to positive effect up to 200 kilometers away. Beyond that it has no measurable effect.

Some worry the silver iodide poisons water. "Silver iodide is a strong compound," said Parkinson. "It is not soluble in a natural environment."

How does Ochoco Irrigation District feel about it?

Like Jefferson County, irrigators in Crook County are facing severe drought conditions that have resulted in water curtailments and a shorter-than-average season. According to Bruce Scanlon, Ochoco Irrigation District manager, the irrigation season for Prineville Reservoir customers began on April 25, and the season did not start until May 6 for Ochoco Reservoir customers.

The water allocations for Prineville Reservoir customers is 0.5 acre-feet, dramatically lower than a good water year when the allocation is as high as 4 acre-feet. Ochoco Reservoir customers have an even lower 0.45 acre-feet allocation. The season for Prineville Reservoir customers is not expected to reach August, while the season for Ochoco Reservoir customers will probably end before July.

Scanlon said that OID has not explored cloud seeding very much but said he would be in conversation with NUID as they learn more about it.

Will cloud seeding work in Jefferson County?

That depends on the climate, and it will take a while to find out. Idaho Power started studying the feasibility of cloud seeding in the Snake River basin in the early 1990s and didn't start its first project until 2003.

The first step is a climate study. How much moisture is in the atmosphere? How often does the area have "seeding opportunities," which may not include all storms?

Will the geology handle extra water?

"Some watersheds are really flashy," said Kunkel. "A rain on snow event can cause flooding. Those are not ideal."

Idaho Power offers this advice:

"Cloud seeding is not a drought busting tool," said Parkinson. "It's a long-term water management strategy."

Going for long periods without storms reduces cloud seeding opportunities. Having done cloud seeding, though, builds up base flows and the hydrologic resilience of a watershed, reducing the impact of drought.

Parkinson says the feasibility study is also essential to determine whether the watershed is conducive to seed from the ground, with aircraft, or both.

"Communicate early with prospective groups," said Kunkel, "from ditch riders to legislators."

More water benefits a variety of interests — environmental, recreational, agricultural — all who benefit should participate in the planning and investment.

Mike Britton, NUID executive manager, has researched the idea of cloud seeding and determined a climatology study for the Deschutes Basin would cost $600,000.

Both Britton and Josh Bailey, NUID general manager, have cloud seeding on their radar. Their immediate priorities involve surviving the drought and installing a pumping station at Lake Billy Chinook.


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