King CountyFor more information about this layer please see the GIS Data Catalog . Channel migration hazards for seven King County rivers: Middle White River, Raging River, Tolt River, Three Forks area of Snoqualmie River, Cedar River, Green River, and the South Fork of the Skykomish River. The Cedar River was updated April 2015, the SF Skykomish June 2017, and the Tolt July 2018. In December 2019, the Middle White River was added, the Raging River was updated, and a revision was made to the updated Cedar CMZ. The Lower Snoqualmie CMZ was added November 2025 after adoption by the Dept. of Local Services.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/0d0701f752084a43b358adfab4d2cd1d_0engKing County GIS Open DataPublicChannel Migration Areas in King County [Washington (State)--King County]Web servicesWashington (State)--King CountyWashington (State)Last Modified: 2025-11-26