Catastrophic Mud Slide in Washington—Could it Have Been Prevented?

The death toll in this rural area 55 miles north of Seattle in Snohomish County is expected to rise. Rain had saturated the ground and led to the collapse of a hillside about 600 feet high and 1,500 feet long. But was the slide foreseeable?

2 minute read

March 26, 2014, 8:00 AM PDT

By Irvin Dawid


"In a press conference Monday (March 24) evening, Snohomish County Emergency Management Director John Pennington said reports of names of people missing or unaccounted have grown from 108 to 176; he emphasized that many of those names could be duplicates," writes Heather Graf of KING-TV, Seattle-Tacoma, for USA Today.

Graf adds that the "number of missing will probably decline dramatically as people are accounted for. Among the missing: residents, construction workers and people just driving by."

"The situation is very grim," Snohomish County Fire District 21 Chief Travis Hots said, stressing that authorities are still in rescue mode and are holding out hope. But he noted: "We have not found anyone alive on this pile since Saturday."

The Seattle Times raises insightful issues about the inherent instablility of the area and whether housing should have been allowed, indicating that the hillside has a history of slides dating "back more than 60 years. One expert says he was shocked when homebuilding was permitted after a big 2006 slide," write Ken Armstrong, Mike Carter and Mike Baker.

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.”

In The Wall Street Journal, it is pointed out that rain may not have been the only contributing factor.

While officials cited recent heavy rains in the area as a prime cause of the slide, David Montgomery, a geology professor at the University of Washington in Seattle, said that the geologic make-up of the hillside was also a factor.

"It's a pile of relatively weak glacial debris," he said, referring to its composition, a loose mixture of sand, gravel and stones.

Finally, some have considered the issue of advanced warning. In 2010, Planetizen's Nate Berg pointed to developing technology from Loughborough University in Leicestershire, England that appeared to hold the possibility of providing an early warning system for landslides.

Perhaps it was Washington Gov. Jay Inslee who summed up best the devastation caused by the Highway 530 mudslide after flying over it. "The scope of this is almost unbelievable", he told The Seattle Times.

Tuesday, March 25, 2014 in USA Today

Young Professional

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban and Environmental Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban and Environmental Planner

Get top-rated, practical training for planners

"Planetizen federal action tracker" logo superimposed over black and white image of US Capitol dome.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

October 28, 2026 - Zachary Whalen

A car drives through a puddle, making a large splash. Rain pours down.

California plans to bury El Niño’s downpour

If the state plays its cards right, it may be able to store a billion acre-feet of El Niño’s water in aquifers.

October 28, 2026 - Grist

A pencil rendering of Foundry Park, which shows skyscrapers and public green spaces.

Chicago breaks ground on $3 billion megadevelopment

The new neighborhood, titled Foundry Park, will one day host 3,700 residences.

October 23, 2026 - Chicago Sun Times

A rendering of a high speed rain station in California, with wide platforms and a sleep train with yellow highlights.

California High-Speed Rail Authority CEO resigns after $600,000 scandal

Under Ian Choudri, the authority used taxpayer dollars to fund first class flights and trips to nightclubs.

5 hours ago - Cal Matters

 A bridge stretches across the Missouri River at Chamberlain, South Dakota.

Want to study the Missouri River? Soon, you may need unanimous approval from 10 states

Legislation would require 10 governors’ permission to study or build projects moving water outside the basin.

7 hours ago - South Dakota Searchlight

Lake Powell with much of the water evaporated.

Desperate measures: Advocates weigh draining Lake Powell to fill Colorado River

Draining the reservoir could reduce evaporation losses by a couple hundred thousand acre-feet.

October 30 - Yale Environment 360