The project involves removing fish barriers at two culvert crossings, reestablishing a natural confluence at the Sammamish River, realigning the Sammamish River Trail to accommodate the new fish-passable stream culvert, and providing riparian terracing for vegetation planting. The project will provide approximately 800 linear feet of stream enhancement, reduce flooding, and open fish access to approximately 1,200 linear feet of the enhanced channel.
Parametrix was responsible for design, permitting, and construction management support and prepared the hydraulic and hydrologic evaluation of the Sammamish River stages at the confluence with Derby Creek. We prepared a 5-year monitoring plan to assess fish passage at the newly replaced culverts, fish use of lower Derby Creek; stream temperatures in Derby Creek and confluence with the Sammamish River; and success of riparian vegetation establishment. Fish salvage activities and associated reporting were also included.