PWA - Philip Williams and Associates in the San Francisco Bay Area, California, and the Pacific Northwest - Consultants in Environmental Hydrology
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Title Edgewater Park Fish Habitat Improvement: Channel Design
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Project Summary Edgewater Park provides 54-acres of public space along the scenic Skagit River in Mt. Vernon, WA. PWA designed a back-channel within the park to improve and enlarge the juvenile salmonid rearing habitat.
Date 2000-2002
Location Mount Vernon, WA              
Client Miller Consulting for the City of Mount Vernon
   
Project Detail
Edgewater Park provides 54-acres of public space along the scenic Skagit River in Mt. Vernon, WA. PWA designed a back-channel within the park to improve and enlarge the juvenile salmonid rearing habitat.

The project included several objectives:

  • Reduce the risk of fish stranding
  • Expand the off-channel low-velocity refugia habitat during high river flows
  • Increase the edge habitat and the complexity and availability of the habitat
  • Minimize operations and maintenance requirements over the long term
  • Preserve the existing infrastructure as much as possible
  • Integrate stable wood debris structures to offer local hydraulic control

PWA performed a comprehensive hydrologic, hydraulic and geomorphic assessment to develop a sustainable and highly functional channel design. The team used Surface Water Modeling System software to develop a two-dimensional hydraulic and sediment transport model of the project site. Using the model, the channel inlet and size the back-channel were designed to maintain a slight scour, ensuring that sediment would not block the inlet. The model was also used to analyze and optimize water velocities and depths for supporting juvenile salmonids.

PWA developed a fine grading plan for the channel and designed biotechnical protection that stabilized the banks and provided cover and habitat to enhance fish habitat. Recommendations on the locations of large woody debris structures were also provided.