Flood season will carry new risks for Stillaguamish Valley this year

ARLINGTON — Danger lingers in the Stilly Valley, months after a mudslide buried an entire neighborhood.

Snohomish County officials have kept close watch on the North Fork Stillaguamish River upstream and downstream from where a mountainside gave way on March 22, killing 43 people and violently reshaping the landscape. They’re most worried about what will happen after Nov. 1, the beginning of flood season. That leaves only two and a half months to prepare.

They’re also on alert for further movement on the hillside itself, though they’ve noted nothing major since disaster struck in the spring.

“We have to have eyes on the river, we have to have eyes on the slide,” said Debbie Terwilleger, the county’s director of surface water management.

At the Stillaguamish Senior Center in Smokey Point on Thursday, Terwilleger was among more than 20 Snohomish County officials on hand to provide a public update on the slide recovery. Government officials outnumbered the audience by nearly four to one.

The conversation touched upon future flood dangers, progress clearing debris, and an eventual memorial to honor the victims. A sheriff’s sergeant addressed persistent — apparently unfounded — rumors of looting in the mile-wide area devastated by the slide.

One member of the audience hugged several county officials as the meeting let out.

“They have answered every question, they have held our hand,” said Rhonda Thompson of Burien, whose family was unhurt in the slide, but lost their cabin of 21 years. “They have been so generous and so kind. All of them.”

What most interested Thompson were the new flood dangers. She said she’s prepared to let crews use her land on the west end of the slide area to perform earthwork, if it helps alleviate upstream flooding.

“Whatever they need to do to save the homes upriver, then do it,” she said.

A second community meeting is set for 6 to 7 p.m. Tuesday at the Darrington Community Center, 570 Sauk Ave.

The initial mudslide blocked the Stilly to the east, forming what some people dubbed “lake Oso.”

To ease the blockage, workers in the early stages of the recovery used heavy equipment to encourage the river to form a new channel downstream, Terwilleger said. The lake soon disappeared.

“We’ve actually seen a tremendous amount of change in terms of what the river looks like since we started our effort,” she said. “There’s a lot of concern about areas that are seeing more sediment, that are seeing more debris accumulate.”

The county and the Army Corps of Engineers have studied ways to dig emergency channels to lessen upstream flooding. They’re also looking to stage machinery and sandbags where they’re likely to be needed most if the river rises to dangerous levels.

There’s unlikely to be enough data to prepare for long-term flood dangers until next year, Terwilleger said.

The county is using devices to measure movements on the slope.

The hillside itself hasn’t moved, but “chunks of the edge have sloughed off,” public works director Steve Thomsen said.

The hillside had slid several times in the past, including a major event in 2006 that blocked the river and which scientists concluded was the root of this year’s catastrophe.

Meanwhile, cleanup work presses ahead in the mile-wide disaster zone.

Contractors are about a month ahead of schedule in screening and hauling away dirt and debris that emergency crews moved during the search for the dead, solid waste director Matt Zybas said. The bulk of that work is expected to be finished by the end of August. The county in June awarded three contracts for the work totaling more than $12 million.

The county is actively exploring a buyout of about 80 private landowners in the slide area.

At least 75 percent of those contacted said they want to learn more about the buyout process, said Gary Haakenson, a county executive director overseeing recovery efforts.

The county sent the Federal Emergency Management Agency an application seeking grant money for the buyouts on Thursday, Haakenson said.

State transportation contractors are working to rebuild Highway 530 through the slide zone by October.

Separately, an independent commission plans to convene Friday to examine the emergency response and land-use decisions related to the March 22 Oso mudslide. The group is tasked with delivering a report to the highest state and county officials in December.

Noah Haglund: 425-339-3465, nhaglund@heraldnet.com. Twitter: @NWhaglund.

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