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Portion of Cedar River to remain closed due to mudslide

Tons of earth cascaded down towards multiple Maple Valley area homes and property during a mudslide Saturday that was estimated to be about 300 feet high and 300 feet across at the base. And state geologists said the land is not yet done sliding.

Firefighters of Maple Valley Fire and Life Safety were dispatched the 21300 block of 221 Avenue Southeast just after 10:00 a.m. They found the mudslide had completely blocked the flow of water in the Cedar River and had forced the river over its banks and through private property. Six homes and one additional property were affected in the semi-rural area. There were no reported injuries.

Capt. Kyle Ohashi with the Kent Regional Fire Authority who was acting spokesman for the Maple Valley Fire Department, said firefighters recommended that residents leave until the river receded, but there were no evacuations. Much of the private property damage was done to lawns, though Ohashi said he saw a carport with about one foot of standing water. He did not have an overall cost estimate on for damage.

The King County Sheriff’s Office ordered an emergency closure to all activities on a roughly half-mile stretch of the Cedar River, including boating, fishing, floating and swimming, from between Highway 18 at the Renton Maple Valley Road to the Maxwell Road bridge.

King County Sheriff’s Office Sgt. DB Gates said the river will remain closed “until further notice,” as crews try to figure out how to clean up the downed trees.

Ohashi said the slide was eerily reminiscent of the fatal mudslide in Oso in March, but on a much smaller scale. Ohashi said the damage and potential for injury would have been much worse had the mudslide occurred in a less rural area.

“It was very lucky,” Ohashi said.

Tim Walsh, Chief Hazards Geologist, said the area remains as “an active landslide” where more material will be coming down as time progresses. The instability includes a triangular area of sand and gravel near the top of the slope that Walsh said has potential to come down all at once and cause more damming and flooding.

“The stabilization is not likely to happen for a while,” Walsh said. “We would need the base of landslide to become vegetated. If we get some spring rains, enough for grasses to grow, that might stabilize it a little.”

Walsh said state geologists anticipate more vegetation will come down into the river over the next month.

“It will be hard to tell when it’s done because right now the surface of the remaining bluff is not cohesive because there is no vegetation covering it anymore,” he said. It will continue moving.”

Ohashi said he is concerned about heavy winds or rain that could force the issue.

“Obviously the danger is very real of it coming down,” he said. “All it needs is the right, or wrong, push.”

 

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