Lower Big Quilcene River Restoration

The lower Big Quilcene River system was constrained by ecological stressors, including levees, which limit floodplain connection and prevent natural channel migration, and also limit large wood recruitment and sediment deposition. The Hood Canal Salmon Enhancement Group and The Nature Conservancy worked to restore natural processes throughout the lower Big Quilcene River alluvial fan and delta. Based on extensive stakeholder outreach, the project team identified multiple goals, including habitat restoration, flood risk reduction, public access and recreation, compatibility with shellfish resources, educational opportunities, and benefits to the local economy.

Anchor QEA then collaborated with project stakeholders to develop three alternatives that proposed multiple actions and allowed various degrees of change to the river system throughout the alluvial fan and delta. We conducted a geomorphic analysis of the alluvial fan and delta that evaluated the potential for the river channel to migrate or avulse under existing conditions for each conceptual alternative. To support the geomorphic analysis, we provided hydrodynamic modeling to evaluate the alternatives’ potential flooding patterns and velocity changes between the alternatives. Anchor QEA worked with the project team to identify and refine a preferred alternative.