Shinglebolt Slough Restoration Project

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Shinglebolt Slough - Project Map

The Shinglebolt Slough restoration project is the first integrated floodplain management project funded under the Community Floodplain Solutions (CFS) program. This project is made possible through the voluntary sale and acquisition of private land along Shinglebolt Slough (next to the Skykomish River just south of the city of Sultan, near the 311th Ave SE bridge). 


Project benefits include:  

  • Retaining quality agriculture parcels for local farm production 
  • Reconnecting and enhancing side channel habitat for endangered salmon  
  • Supporting flood hazard reduction and mitigation efforts 

See the Shinglebolt Slough project fact sheet (PDF).

The Skykomish River and floodplain near Sultan is a dynamic reach where the mainstem migrates and splits with actively connected channels across the floodplain. Floodplain side channels in this reach provide key habitat for threatened salmon and steelhead spawning and rearing. Recurring flooding and geomorphic changes also threaten floodplain residents and agricultural productivity.

Project Description

The Shinglebolt Slough project is a mainstem, off channel, riparian, and floodplain restoration project. The project is located along the Skykomish River mainstem and active floodplain. 


The Shinglebolt Slough project goals are to:

  • Reconnect the floodplain side channel at average spring flows for salmon out-migration
  • Restore off-channel and riparian habitat forming processes
  • Reduce flooding impacts in the adjacent area
  • Retain viable agriculture land use on the Mann Road floodplain

Desired project outcomes are:

  • A self-sustaining side channel with diverse habitat features and developing channel complexity
  • A natural, complex mainstem edge where sediment and woody debris can suspend, sort, and erode
  • Flows and channel changes that mitigate and do not increase risk to infrastructure -- including 311th Ave roadway and Bridge 151 (Shinglebolt Slough) -- and adjacent agricultural fields and homes
  • A healthy, maturing riparian forest that is free of invasive species
  • Retention of approximately 10 acres in viable agriculture
  • Reduction in overall flood hazards in the nearby and adjacent floodplain and infrastructure 
  • Recreation access and environmental education opportunities 

Snohomish County and consultants are meeting with local stakeholders to gather input on the restoration project design. 

  • A public Design Charette event is planned for late 2022. The project team will be incorporating ideas and concerns from this engagement as they develop initial design elements. 
  • Results of these efforts will be made available for public review and comment through community meetings with stakeholders in early spring 2023.
  • Final design is expected by summer 2023, with construction projected to begin in summer 2024.

Contact us (see right side bar) to receive email updates about this project, and to learn about future public meetings and public comment opportunities.