South Fork Skykomish River Channel Migration Zone Study and Map
Final Map and Public Rule
The South Fork Skykomish Channel Migration Zone (CMZ) study and map were completed in 2017. The amended channel migration public rule adopting the South Fork Skykomish CMZ became effective in September 2017. Following are links to the final map, related study, and amended channel migration public rule. (Please visit our Acrobat Help page for help with Acrobat.)
- South Fork Skykomish River channel migration zone map (PDF, 1.08 MB)
- South Fork Skykomish River channel migration study and map (PDF, 17.2 MB)
- King County Channel Migration Public Rule (PDF, 144 KB)
- Appendix B to the King County channel migration public rule (331 KB, PDF)
Paper copies are available for review at the following two locations:
- King County Department of Local Services, Permitting Division, 35030 SE Douglas Street, Suite 210, Snoqualmie.
- Skykomish Library, 100 5th Street, Skykomish, WA (external link).
Channel migration is the process in which a river moves across its floodplain either by steady progressive erosion or by suddenly switching to a new course. Channel migration is a type of flood hazard, different from inundation hazards. (Visit the channel migration page for more information)
The South Fork Skykomish Channel Migration Zone (CMZ) Study and Map, adopted August 8, 2017, applies to the South Fork Skykomish River from the confluence of the Foss and Tye rivers (River Mile 19.7) to the King-Snohomish county line (river mile 6.6). The South Fork Skykomish CMZ map will be used to regulate land use within affected areas identify hazard areas, and help property owners make informed land use decisions.
New development generally is not allowed within the severe hazard area of the channel migration zone and new development may be restricted within the moderate hazard area of the channel migration zone.
CMZ map preparation
The South Fork Skykomish CMZ study and map were prepared using CMZ mapping methods specified in the King County Channel Migration Zone Public Rule, consistent with policies in the King County Flood Hazard Management Plan, Washington State Shoreline Management Act, and the Washington State Department of Ecology Channel Migration Assessment.
Map adoption process and public involvement
CMZ maps are adopted by amendment to the King County channel migration public rule under authority of the King County Code 2.98, 21A.02, and 21A.24. Channel migration zone mapping is required by the Washington State Shoreline Management Act.
The draft South Fork Skykomish CMZ study and map underwent public review in 2017. Public comments were considered in finalizing the CMZ study and map.
April 20, 2017: King County hosted a public meeting in Skykomish attended by approximately 45 people. King County staff presented the draft South Fork Skykomish River CMZ study and maps and described the channel migration public rule amendment process by which the CMZ map is adopted. There was a question and answer period and the CMZ map was on display. South Fork Skykomish River Channel Migration Zone Draft Study and Map Presentation (PDF, 5.39MB)
- May 20, 2017: King County met with the Timberlane Homeowner’s Association and the community of Baring at two separate meetings and presented the draft South Fork Skykomish River CMZ study and maps and described the channel migration public rule amendment process by which the CMZ map is adopted.
- June 14, 2017: The public comment period closed. King County Department of Natural Resources and Parks responded to all comments and made minor revisions to the draft CMZ study and map.
- August 7, 2017: Final South Fork Skykomish River CMZ map was adopted by the King County Department of Permitting and Environmental Review by amending the existing channel migration public rule.
- September 7, 2017: Final South Fork Skykomish River CMZ map became effective.
- King County Channel Migration Zone Public Rule
- King County Flood Hazard Management Plan
- Washington State Shoreline Management Act (external link)
- Washington State Department of Ecology Channel Migration Assessment (external link)
For more information about the draft South Fork Skykomish CMZ study and map or channel migration mapping methods, please contact Jeanne Stypula, Managing Engineer, River and Floodplain Management Section, Water and Land Resources Division, Department of Natural Resources and Parks.
For more information about King County’s existing land use regulations in channel migration zones, please contact Department of Local Services, Permitting Division.