Sammamish River Tributary Restoration Design

Redmond, WA

Stream Channel Design /Geomorphic Assessment/ Stream Channel Surveys/ Hydrologic, Hydraulic and Sediment Transport Analysis/Bank Stabilization Design

HGD has worked closely with Otak Inc. to provide geomorphic analysis, sediment transport analysis and channel restoration design for a tributary to the Sammamish River near Redmond, WA. This channel is currently impacted by high sediment loads emanating from an unstable upstream ravine and has numerous fish passage barriers preventing salmonid spawning. The restoration design includes; a high-flow bypass to mitigate erosion problems in the ravine area, removal of an in-line sedimentation basin, fish passage stream simulation culverts, flood plain reconnection, increased channel sinuosity as well as large woody debris (LWD) structures for added habitat and stream bed stability. Detailed hydraulic modeling, sediment transport and sediment budget analysis were conducted to confirm that the proposed design will result in improved bed load transport, channel stability and fish habitat/fish passage conditions in the reach.

Client: Otak Inc., City of Redmond, WA.