Otter Point Estuarine Habitat Restoration

HENDERSON environmental design professionals teamed the Columbia River Estuary Study Taskforce and the National Park Service to develop a comprehensive restoration plan that interprets the natural estuarine landscape of the Otter Point Estuarine Habitat Restoration Project site along the Lewis and Clark River, a tidally-influenced tributary to the lower Columbia River.  HENDERSON’S design team cooperatively developed alternative conceptual restoration designs after preliminary assessment and evaluation of existing site resources and condition, and upon conducting cultural/historical analysis.  HENDERSON’S restoration design alternatives examined levee breaching, tidal slough excavation, invasive species management, off-channel fish refugia, estuarine plant community diversity and structural restoration, and potential development of an interpretive trail/educational signage component with local schools.  To mitigate the risk of flooding other properties, the levee present along the north site boundary was enhanced to meet USACE requirements.  HENDERSON’S design team prepared key geotechnical guidance resulting in the first Section 408 Permit (levees and dams) issued by the Portland branch of the US Army Corps of Engineers that met or exceeded criteria established by the Corps post-Hurricane Katrina (2006).  HENDERSON’S team evaluated the feasibility and cost efficiencies of using on-site material and soil from the existing levee for the levee enhancement; and developed geotechnical recommendations for design and construction of the dike.

HENDERSON constructed their estuarine restoration design in 2011-2012, including excavation of multiple backwater channels, sustainable re-use of excavated materials for use in the levee construction, installation of extensive shallow-water brush-wrack and LWD habitat structures, and the construction of the northern setback levee that meets current Corps of Engineers post-Katrina standards.  Our Otter Point Estuarine Habitat Restoration Project reconnects more than 17-acres of historic lower Columbia River Basin tidal wetlands to riverine and tidal inundation, restoring high-value salmonid off-channel habitat.

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