Risk of Washington mudslide ‘unforeseen’? Warnings go back decades

Ken Armstrong, Mike Carter and Mike Baker in the Seattle Times: While a Snohomish County official said the area hit by the mudslide “was considered very safe,” the hillside’s history of slides dates back more than 60 years. One expert says he was shocked when homebuilding was permitted after a big 2006 slide.

Since the 1950s, geological reports on the hill that buckled during the weekend in Snohomish County have included pessimistic analyses and the occasional dire prediction. But no language seems more prescient than what appears in a 1999 report filed with the U.S. Army Corps of Engineers, warning of “the potential for a large catastrophic failure.”

That report was written by Daniel J. Miller and his wife, Lynne Rodgers Miller. When she saw the news of the mudslide Saturday, she knew right away where the land had given way. Her husband knew, too. “We’ve known it would happen at some point,” he told The Seattle Times on Monday. “We just didn’t know when.”

Daniel Miller, a geomorphologist, also documented the hill’s landslide conditions in a report written in 1997 for the Washington Department of Ecology and the Tulalip Tribes. He knows the hill’s history, having collected reports and memos from the 1950s, 1960s, 1980s and 1990s. He has a half-dozen manila folders stuffed with maps, slides, models and drawings, all telling the story of an unstable hillside that has defied efforts to shore it up.

That’s why he could not believe what he saw in 2006, when he returned to the hill within weeks of a landslide that crashed into and plugged the North Fork of the Stillaguamish River, creating a new channel that threatened homes on a street called Steelhead Drive. Instead of seeing homes being vacated, he saw carpenters building new ones. “Frankly, I was shocked that the county permitted any building across from the river,” he said. “We’ve known that it’s been failing,” he said of the hill. “It’s not unknown that this hazard exists.”...

US Airmen with the Washington National Guard in Oso on March 27, 2014, public domain