SUN VALLEY • Derek Blestrud was already sweating as he thought about the prolonged hot spell his weather models were predicting a week ahead of the onset of triple digit temperatures. Even more worrisome was that the models weren’t indicating a cool off even 10 days out.
That’s a concern for irrigators and livestock producers who are concerned about how the heat will impact their crops and animals, and also if you are a meteorologist for Idaho Power. With reservoirs already low after a subpar snowpack and little wind accompanying the warm up, Idaho Power will be pressed to keep up with power demand over the next week or so.
That’s why Idaho Power officials began looking at cloud seeding as a way to enhance snowpack and increase reservoir levels. After more than a decade of trials in the Payette area, Idaho Power is expanding its efforts in the Big Wood, Boise and Upper Snake basins.
Jon Bowling, an Idaho Power engineer, said the company hopes to use a cost-share program through the Idaho Department of Water Resources to expand cloud seeding operations across southern Idaho.
“There are only a couple of different ways to add water to the system,” Bowling explained to water managers and water law attorneys during the Idaho Water Users Association’s annual summer law seminar. Water can be brought in from outside the system, but that is often expensive, he said.
Users can curtail consumptive use, but experiences reducing groundwater use in Idaho have already demonstrated how difficult that can be. Or water users can make more water.
“Weather modification is a way to bring water into the system,” Bowling said. Idaho Power research indicates that cloud seeding can produce 1 million acre-feet of water annually across southern Idaho. That was a figure that got lawmakers attention during the 2015 legislative session.
Blestrud has focused cloud seeding efforts in areas where the mountains are already interacting with a storm system to get the natural lift needed to put the silver oxide in place to start precipitation. Precipitation has increased every year that cloud seeding has been done in the Payette area, he said. Some years, such as last winter, the increase is a paltry 1 percent but the long-term average is 15 percent.
Using a more modest estimate of a 10 percent bump in precipitation and the USDA Natural Resources Conservation Service’s streamflow model, shows an increase of about 200,000 acre-feet of water in the Boise area, 100,000 acre-feet in the Big Wood and almost 200,000 acre-feet in the Upper Snake compared to not doing cloud seeding.
While the results are promising, Idaho Power has been careful not to do more cloud seeding than the system can handle. “Flooding is a concern,” Blestrud said. “We don’t want to create more water than we can handle.”
Officials monitor the snowpack throughout the winter and evaluate flooding potential including runoff from rain on mid-elevation snow. While some groups have expressed concern about silver oxide in the environment, Blestrud says the material is inert and does not impact aquatic creatures.
Cloud seeding has been used for fog or hail suppression in other regions of the U.S. for decades. Essentially, silver oxide is used to provide more efficient ice nuclei at higher temperatures than would occur naturally. Ice doesn’t form naturally in clouds until temperatures reach 5 degrees, but using silver oxide can cause ice to form at 22 degrees. Although the practice is most efficient below 17 degrees.
“Idaho Power knows where we are at and we’re at the end of the ditch. We’ve subordinated all our water rights to upstream beneficials uses,” Bowling said. “We’ve got to get more natural flow in streams.”
Increasingly, manipulating Mother Nature to make more snow is one way to do that.