King County declares flood-threat state of emergency

King County declared a state of emergency this morning to prepare for the possibility of flooding this fall and winter in the Green River Valley.

County Executive Kurt Triplett said damage last winter to the Howard Hanson Dam above Kent, Renton, Auburn and Tukwila means that more water than usual might have to be released from the dam than during the rainy season, dramatically increasing the odds of flooding downstream.

The declaration will let the county wave procurement rules, bypass environmental regulations and seek federal reimbursement for work to build up and repair levees and move equipment between now and the wet season. Just last year, the county started spending about $35 million a year on levee improvements.

"I hope to assure the region we are doing all we can," Triplett said.

County officials have said there are too many possible scenarios to accurately predict how floods could affect the valley.

At a meeting last night at Green River Community College, Col. Anthony Wright of the Army Corps of Engineers told a crowd of hundreds of valley residents that the odds of flooding could be as high as one-in-three this winter, but that the Corps is working on temporary fixes to the dam, which he hopes will lower those odds.

But it all depends on how wet fall and winter are and how frequently the storms come. And that won't begin to be clear until early November.

"We are not in control," Councilmember Julia Patterson said. "Mother Nature is in control."

Last winter, federal officials discovered that the dam's right abutment was damaged. The Corps has been working through the summer on a temporary fix, but Wright has said he probably won't allow the reservoir behind the dam to reach full capacity, just in case. Given the right volume and frequency of storms, he might have to release more water than the river system can control, he said, in order to maintain the dam's structural integrity.

In a severe flood, county officials suspect up to 26,000 people might need to evacuate. Since so much of the region's manufacturing, warehousing and distribution takes place in southwestern King County, a shutdown of the floodplain could lead to economic losses of $46 million a day. The Federal Emergency Management Agency has said severe flooding could cause $4 billion in damage.

Patterson said the declaration alone likely would clobber the real-estate market. "Who would buy a house by the river today after this is signed?" she asked.

Trying to prepare in advance leaves the county "damned if we do and damned if we don't," Patterson said. The county is already facing a budget deficit and preparations could cost an additional $35 million for floods that never happen. Not preparing, however, could put people, businesses, homes and county facilities at even greater risk if flooding is severe.

But "our goal is to protect their [valley residents'] lives and their property," Triplett said. "Today's actions give us the best chance."

Craig Welch: 206-464-2093 or cwelch@seattletimes.com