The residents living along the rim of Northeast 127th Circle own property from the top of the bluff down the slope to where it meets Salmon Creek Greenway below. When the neighborhood was built in the early 1990s, Athay and Kelly said, they had to obey certain rules, such as not cutting the trees on the hillside and abiding by setbacks. Kelly said the catastrophic landslides in Oso prompted him to have his slope inspected by a geologist, who said the soil is remnants of the ice-age Missoula Floods, but the soil was compact.
Everything was fine until last year when the first slide happened.
Since then, Athay said, the slope has been falling bit by bit into the creek below.
“The event is called mass wasting,” Washington Department of Ecology Spokesman Dave Bennett said in an email.
He also said that while the sediment and debris choking Salmon Creek could adversely impact the stream, Ecology likely won’t get involved because the landslides are considered a natural event.
Jeff Mize, spokesman for Clark County Public Works said the county won’t get involved, either. He noted that the homes are right on the edge of a landslide hazard area.
“I certainly feel for the families having their property slowly being eating away by a landslide, but it’s not the county’s issue,” Mize said. “I’d urge them to hire a geotechnical consultant to see what’s going to be done.”
Steven Sobieszczyk, an earth scientist at the U.S. Geological Survey Oregon Water Science Center, said the slides in Salmon Creek are not anomalies, but rather a reality throughout the Portland metro area and along the West Coast in general.
“Property damage due to landslides is a costly and fairly common occurrence in the Pacific Northwest,” he said.
Indeed, the 2015 Oregon Natural Hazard Mitigation Plan says the average annual repair costs for landslides in Oregon exceed $10 million.
“Most people buy these properties because of the beautiful views, but there are risks associated with living there,” Sobieszczyk said. “If you’re building on a slope and adding weight, you’re going to increase the potential of landslide.”
While landslides might be a relatively common issue in the Pacific Northwest, Michael Barry, spokesman for the Insurance Information Institute, an industry-funded consumer education organization based in New York, said landslides are usual enough that typical homeowner’s insurance polices won’t cover them.
“The only policy I’ve heard of that covers landslides is a so-called ‘difference of conditions policy,’ but it’s very rare and probably not even sold by a standard home insurer,” Barry said.
Athay and Kelly said they plan to look for solutions to stop their hillsides from moving. But Sobieszczyk said once a landslide has occurred, others are extremely likely to follow, and stabilizing the slope is very challenging, he said.
While the residents of Northeast 127th Circle are feeling the effects of living with landslides, they’re hardly the only area property owners at risk.
Clark County’s landslides hazards map shows the slopes on both sides of the Salmon Creek Greenway as areas of potential instability.