Kittitas County’s WA dams are safe and it would take a Cascadia-earthquake-level event to cause a failure like the one that occurred at the Oroville dam, officials said this week. More than 200,000 people living downstream from the Oroville Dam in California were evacuated earlier this month after engineers noticed damage to an emergency spillway. Kittitas County, WA has 18 dams. Six of those dams are operated by federal agencies, and the remainder are under the jurisdiction of the state, according to county’s 2012 hazard mitigation plan. Five of the dams are labeled as “high” hazards in the plan — Cle Elum, Easton, Kachess, Keechelus, and Upper Sunlight Lake — based on the potential consequences to downstream life and property, according to the county plan.
Aaron Galayde, water storage supervisor for the Bureau of Reclamation’s Yakima field office, said the label refers to the impact a failure might have. The dams aren’t at risk of failing, he said.
“All of the dams are getting old. But there are no major dam safety issues or concerns on the Yakima Project at this time,” Galayde said. “There is always the potential of something catastrophic occurring, but it would have to be a tsunami or Cascadia-earthquake-like event for the facilities within the Bureau to fail.” The remainder the county’s dams are ranked as low risk, with no lives at risk downstream, according to the county plan. Chris Lynch, river operator with the Bureau of Reclamation, said this has been an average year for precipitation and snowfall in the region. The Bureau isn’t expecting out-of-the-ordinary runoff this spring that would strain the system, he said.
Galayde said the bureau does extensive inspections and monitoring of all of its dams. A team of geologists, civil and mechanical engineers does annual inspections on the structures. Bureau of Reclamation staff from Denver also do internal inspections every four years. The bureau has instruments monitoring dams 24 hours a day and collecting data. “The bureau has enough checks and balances in place so that issues and potential issues will be caught before they end up being like this Oroville dam,” he said. “We’ve got directives and standards that tell us when to do things and what to do and we abide by them to keep the water where it is supposed to be which is upstream in the reservoirs.” The bureau also keeps a cushion in the reservoir based on potential flows to prevent flooding, Galayde said. It monitors snowpack and tracks weather patterns to know exactly how much water will be moving through the system.
“We’re always looking at it to manage the water as frugally as possible. There is no way we’re going to waste water because it is such a precious commodity, but we do have to work in a safety factor in the reservoirs,” he said. The dams in Kittitas County are getting old, but are well built, Galayde said. “Cle Elum’s construction has good geology. It is in a sense one of the tightest dams we have in our inventory. It just is a good glacial foundation area to put a dam. It is really nice,” he said. The Oroville dam in California is unusual in how much water it holds back, Galayde said. It is the tallest dam in the country at 700 feet. “Its inflows are enormous its outflows are enormous. It is a unique monster and it sounds like they missed some warning signs,” he said.
Thank you, Ron
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