Downstream from dam, valley residents and businesses prepare for worst

The Green River snakes out of the Cascades into southwest King County, where wary residents watch it like a fuse.

Since a January storm damaged the Howard Hanson Dam, the valley has been readying for the possibility that this thin, lazy stream might swell into that area's worst flood in nearly half a century.

Apartment renters have broken leases and paid penalties to move away, while some homeowners have designed scaffolding to hoist possessions to keep them dry. Businesses have trucked in dirt and pallets of sandbags, and stacked 4,300-pound concrete blocks around their doorways.

The dramatic and sometimes expensive precautions come amid a recession that already has many businesses and individuals teetering toward financial ruin. And some fear the safeguards won't even work.

"I don't think people really understand the stakes," said Dean Conti, who has owned a machine shop off West Valley Highway for two decades. He worries high water could drive him out. "If we get the kind of flood they say is possible, this place may never be the same."

Because of leaks in the dam's north abutment, the Army Corps of Engineers may release more water than normal this winter to avoid stressing the dam and causing a catastrophic flood should it fail.

But those releases themselves may put parts of southwest King County, Kent, Renton, Auburn and Tukwila under 1 or 10 — or even more — feet of water.

The corps has said the odds of flooding could be as high as 1 in 3. So residents, businesses and governments are spending millions of dollars to prepare.

At a Kent campus where Boeing develops military surveillance aircraft and drones, crews worked overtime shuttling data-heavy computers to higher ground and will erect an 8-foot-high berm around the entire site. Puget Sound Energy plans to seal off transmission substations and is hunting for a new building to store its stockpile of meters, transformers, pipes and conduit that supplies emergency-repair teams as far away as Bellingham.

King County, the Red Cross and the valley cities have sent mailers, gone door to door with translators, and put together evacuation plans for nursing homes and hospitals. They've urged 26,000 residents to buy flood insurance, pack emergency kits and buy battery-powered radios.

The state told businesses to limit storage of hazardous waste. Millions are being spent to shore up and add height to weak levees. King County has moved its election headquarters, has begun walling off a jail and courthouse and plans to position boats to row workers through high water to its Renton sewage plant.

Still, so much floodwater could seep into wastewater pipes that "we may actually have to ask people to conserve water — not because there's not enough of it, but because there's way too much of it," said Pam Bissonnette, assistant King County executive.

Even outside the flood plain, the system could back up and flood homes through the toilets, "a very, very real possibility," she said.

Hazardous waste

The peril originates from the thing that brought the region to life. The Green River Valley was once farms and scattered businesses that flooded often. The dam's arrival in 1961 transformed it with a promise: Water would rarely leave the river's banks, and even then it wouldn't rise much.

Now this part of King County hosts nursing homes and riverfront mobile-home parks for the elderly and some of the county's poorest residents, including immigrants who speak dozens of languages but little English. It's a transportation hub for food distributors and businesses from Ikea to Starbucks, and a Pacific Northwest manufacturing nerve center. There are tens of thousands of employees, 104 million square feet of buildings, a 6,000-seat arena and 125 companies working with lots of hazardous waste — all within the flood plain.

Corps contractors are working to fix leaks in the dam's north abutment, but given bad luck and the right storms, floods could cause $4 billion in damage and curtail $46 million a day in business.

The river's levees were built in the 1940s and '50s, pushed up from the flood plain to hold at least 12,000 cubic feet per second (cfs.) of water. But even a moderate flood could reach 17,600 cfs. — about 60 times more water than the river holds in midsummer. In a wet year, planners suspect, floodwaters could reach 25,000 cfs.

Either scenario would have drowned Alicia Powell's ground-floor Auburn apartment in water. When she learned of that possibility in September, Powell was terrified. "I had butterflies. I was losing sleep."

She and her husband are employed but $30,000 in debt. And they'd just signed a new yearlong lease that their complex wouldn't let them break. She fell into a common category — her lost deposit plus a $700 penalty posed a hardship, but she didn't qualify for public help.

Powell moved anyway, to a new complex on a hill. "The thought of just getting flood insurance and waiting for the water did not seem like an answer," she said.

Lloyd Peterson's mother lives in a retiree mobile-home park along the river near a highway that officials predict could end up underwater. But emergency officials are still working on evacuation and notification plans.

"This complex is 3 or 4 feet below that road," Peterson said. His mother could stay with him in Shoreline, but he fears for her neighbors. "These are people 55 to 90. Some are hard of hearing. It stresses them out because they can't get any answers."

Ken Frankel, president of Three Sigma Manufacturing in Kent, is frustrated, too. His life is his business, but he's not sure how to protect it. He doesn't even know how many sandbags he needs.

"We need better information. Somewhere between 'I have no idea' and complete speculation probably lies some pretty good information," Frankel said. "What are the probabilities? If the street floods 2 feet and lasts for two weeks, that's different than a flood of 7 feet that lasts an hour. I can probably survive the first, but the second presents a real problem for me."

But the scale of the flooding isn't the only calculation. Auburn Mayor Peter Lewis fears a steady string of small floods that arrive week after week, wearing his community down. He's not sure the region has the stamina.

Water over the dam

A personable Army Corps colonel with a no-nonsense style ultimately will decide how much flooding to cause.

With his square jaw and gravel voice, Col. Anthony Wright lends an air of competence, which he uses in meeting halls packed with angry, anxious people, typically abandoning microphones and shouting like a drill sergeant.

He says he understands everyone's frustration, but he says there are too many competing factors for him to provide more concrete data.

Flooding depends on the severity and frequency of storms, on how much time between them he has to drain the reservoir, on levees that weren't built to run at capacity week after week and are subject to sloughing and erosion. There are logs in the river that, once dislodged, could race like torpedoes downstream and blow out the levees.

And he's hopeful dam repairs will substantially pare back the odds of flooding, but he maintains it's too soon to say.

"I know it's not what people want to hear," he said. "But I've been involved in a lot of floods, and the one thing you can count on is, they don't go according to anyone's plans."

Wright knows what he's talking about. He ordered water released from a White River dam last winter, causing unexpected flooding in the town of Pacific.

"I had released water like that in November, and it hadn't flooded the town," he said. "I released it in January and it did. Same amount of water. Not something I foresaw. Not something I expected. Something that troubles me to this day."

In the meantime, business owners like Conti struggle to make fast decisions that could alter their entire future.

He's already $900,000 in debt after purchasing a new machine he needed to stay in business just before the economy tanked last September. Now he suspects he'll spend an additional $10,000 he doesn't have to stop a flood that may not come.

"I'm not mad, I'm not looking for anyone to blame," he said. "But the clear message to me is that I'm not going to get the help I need to prepare."

His colleague down the road, Greg Larkin at Larkin Precision, has stacked 4,300-pound blocks of concrete around his doors and walls and bought gasoline-powered pumps to suck floodwaters from his shop. He says he's confident it will keep water out.

Conti may do something similar, or he may install metal plates wrapped in plastic around his shop's exterior doors and support them with sandbags. He plans to stash a boat, water, food and supplies, and he has already decided: He won't evacuate. He needs to be nearby to protect his business.

"What choice do I have?" Conti asked.

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