KPLU Local News
(2009-08-26)
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SEATTLE, WA
(KPLU) -
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Volunteers may soon be knocking on the doors of 20,000 residents in south King County, to warn them about flooding this winter on the Green River. The Howard Hanson Dam won't be at full capacity. The cost to protect public facilities alone, including a county jail and elections office, could run into the tens of millions of dollars.
Already brochures have gone through the mail to everyone living in the potential flood zone. It's an area that hasn't flooded in half a century, since the Howard Hanson Dam was built upstream on the Green River (in 1962). After a briefing about the potential for waters to go as much as 10 feet over the levees this winter, members of the King County Council worried people may not realize the risk. They urged Assistant County Executive Pam Bissonette to arrange for in-person doorbelling for every residence in the flood zone.
Bissonette agreed to work up a plan. Red Cross volunteers are already set to doorbell "vulnerable populations" on September 11th.
Major businesses are also making contingency plans. The valley between Tukwila and Auburn houses major warehouses for the region's food supply. FedEx has a distribution center there. Boeing is there. And, in a worst case scenario, the county jail could face an evacuation. The county elections office is on low-ground in Renton. Moving or protecting such facilities may require as much as $35 million. The County Council is preparing to allow the Executive to declare an official flood emergency before any flooding happens, to speed up the permitting process.
The Army Corps of Engineers is currently building a temporary buttress at the dam, which started leaking last January. A permanent fix could take several years to design, pay for and build.
Some local officials, and even a brochure from King County, have said the dam will hold just 30% of capacity this winter. The Army Corps says that's not quite true. But, the Corps is not able at this point to say what volume of water the dam will withstand. Those decisions will be made on a case-by-case basis, during the winter, depending on how big the storms are.
Last January's storm was extreme--forcing the highest water levels on record at Howard Hanson Dam. Seepage could be seen this spring when waters reached 45% of those record levels. But, the Corps allowed higher levels this summer, to supply water for Tacoma, equal to 62% of the all-time record. Current repairs could allow at least that much flood storage.
With so much uncertainty and risk, it's hard for anyone--from the homeowner to county officials--to know how much to spend on protection.
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