Green River Valley: Anxiety ebbs over flooding potential

Green River Valley residents began settling into a new reality Thursday: The odds of severe flooding have dropped substantially due to repairs on the Howard Hanson Dam, but a serious threat may exist for years.

The announcement by the Army Corps of Engineers that flood risks along the river had fallen from as high as 1-in-3 to about 1-in-25 was greeted by enthusiastic relief.

But that relief was often followed by barely contained frustration that months of high anxiety have come at great psychic and financial expense — and that the wait for a permanent fix could sap the region further even if a flood never comes.

"I was thrilled to hear it," Kent Mayor Suzette Cooke said Thursday. She hoped the announcement would "relieve some of the hysteria and rash decisions that residents and businesses have made in looking to flee the area."

Since a January storm damaged an earthen abutment to the dam, government officials have scrambled to put in a temporary fix — pumping a half-million gallons of grout into the abutment so the corps could hold back water like normal during heavy rains.

Governments, residents and businesses have spent millions fortifying buildings, raising levees and planning evacuations for fear the corps might have to release water during a downpour, causing several feet of flooding along the river from Tukwila to Auburn.

With at least a few businesses already moving out, the valley faces a new challenge: maintaining vigilance for what could be years while keeping the region's economy moving.

"I think everybody had been trying to be prudent and I applaud them for that," said Teresa Hutchens, vice president of Plemmons Industries, which leases office, industrial and retail space in Kent and has seen longtime tenants leave. "But ... it's created such an incredible fear that it was like the sky was falling in. Hopefully, now we can find a balance."

On Thursday, Corps of Engineers Col. Anthony Wright said new tests show the grouting appears to be doing its job — helping bind earthen material to slow the seepage of water enough that he could increase the capacity of the reservoir behind the dam from roughly 33 percent of normal to about half.

That in turn reduces the risk that he'd have to cause flooding in the heavily populated stretch of river below Auburn to about 1-in-25. That risk drops to about 1-in-33 when combined with the thousands of giant sandbags that are being stacked on top of the levees to increase the capacity of the river channel itself.

"We've gone from a bad situation to one that's not so bad," Wright said. He added, though, that the risk is still high, calling it "better than before the work we have done, but not good enough to stop preparing."

Wright maintained that a series of storms carrying heavy moisture from the subtropics, known as a Pineapple Express, could still stress the dam and force him to release enough water to cause a flood. The damage to the dam is blamed on similar storms in January.

When the dam is working properly, the flood risk is 1-in-140, but a permanent fix — likely the construction of a concrete wall built within the abutment — is probably three to five years away.

Initial reactions to the corps' announcement were jubilant. "I think it's outstanding news," said King County Executive Kurt Triplett.

The county, despite a budget crisis, has spent nearly $20 million in preparations. About $8 million for levee work came out of tax revenue gathered through a flood-control district. The county spent an additional $10 million to move the county elections office to the airport, and to fortify a regional justice center and sewage-treatment plant in Renton. That was paid out of $27 million the county borrowed and plans to repay through a future bond issue.

Triplett said he doesn't regret any choices; the county still feels the moves are necessary. But the county will probably postpone evacuation of the county's animal shelter in Kent and take a second look at moving courts and inmates from Kent's Maleng Regional Justice Center, which is now ringed with protective concrete blocks.

Dean Conti, who owns a precision-machine shop in Kent where equipment is too heavy and expensive to move, was overjoyed by the corps' announcement.

"It's certainly good news," said Conti, who has worried about how best to protect his business. He'd spent thousands of dollars buying insurance, water pumps and other preparations, and had planned to park a boat outside his shop — and may still. "And I don't find fault with anybody," he said. "They told us what they didn't know, and now they know more."

Greg Larkin, who owns another machine shop, said he, too, is pleased, but said the flooding odds are still too high. "If someone told you you had a 1-in-25 chance of winning the lottery you'd probably buy hundreds of tickets," he said.

That is where the complication lies.

"The new percentage sounds great, but the reality is we had just that type of storm event 10 months ago," Triplett said. "I'm definitely going to be sleeping easier ... , but we're not out of the woods."

King County Councilwoman Julia Patterson agreed. "This is not over," she said. "For five years, we have to hope that Mother Nature will choose to pass us by with her Pineapple Expresses. We have to continue to be diligent."

But Cooke and Hutchens in Kent said officials have to find new ways to communicate or ameliorate that risk or the valley will be a very different place in five years.

"I had a tenant with me for 19 years who left on Monday," Hutchens said. He needed to expand, but refused to do it in her valley complex. "He said, 'I was driving over the bridge and I looked at those big sandbags and I just can't.' "

Seattle Times staff reporter Keith Ervin contributed to this story.

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