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This research guide will focus on land use and sustainable development issues associated with the March 22, 2014 landslide which took place along SR 530 between Oso and Darrington in Snohomish County, Washington.
Last Updated: Apr 28, 2014 URL: Print Guide RSS Updates

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Oso, Washington Landslide

On Saturday, March 22, 2014, at about 11:00am PDT, a large landslide occurred near Oso, Washington, located in the northwestern portion of the state. [1]  According to the USGS, "Recent rain conditions and soil saturation led to the onset of the landslide." [2]  Debris from the landslide "covered about 30 houses and 0.8 miles of State Route 530."[3] The resulting debris field is is "as deep as 60 to 75 feet in some places....[and] [i]n many places it is 15 to 25 feet deep.' [4]  As of April 1, 2014, there are 27 confirmed victims of the landslide and 22 people are still considered missing. [5] Some websites, including the Snohomish County website, refer to the event as the SR 530 Landslide.[6]

This area has been the subject of geological review since the 1950s.  According to the Seattle Times, "The hill that collapsed last weekend is referred to by geologists with different names, including Hazel Landslide and Steelhead Haven Landslide, a reference to the hillside's constant movement.  Some residents, according to a 1967 Seattle Times story, referred to it simply as 'Slide Hill.'" [7]

[1] Jessica Robertson, Landslide in Washington State: USGS is Working with Partners to Provide Up-to-Date Information, USGS Science for a Changing World (Apr. 1, 2014 9:45 AM),

[2] Id.

[3] Id.

[4]  Matt Pearce, Washington Mudslide Death Toll at 27; Some Victims Still Unidentified, Los Angeles Times, Apr. 1, 2014,,0,3366518.story#ixzz30BRFPMbC.

[5] Staff et al., Oso Mudslide Search Winding Down; 2 Still Missing (Apr. 25, 2014 10:14 AM),

[6] 530 Slide News & Resources, Snohomish County Washington, (last visited Apr. 1, 2014).

[7] Ken Armstrong, Mike Carter & Mike Baker, Risk of Slide 'Unforseen'? Warnings Go Back Decades, Seattle TImes, Mar. 25, 2014,


    United States Geological Services (USGS)

    Research Guides - specific to Oso Landslide

    The following research guides address the March 2014 Oso landslide.

    Legal Research Guides - Washington State

    • Washington State Law Library
      Quick links for Washington State Legal Research from the Washington Courts website.
    • MRSC (Municipal Research and Services Center)
      The MRSC of Washington State includes legal research links relating to municipal government. Topics included are Environment, Planning, Public Safety, and Legal. This site has links to city and county codes as well as summaries of relevant cases.

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