Coho Creek Fish Passage Project - Seaside

Coho Creek is a tributary to Neawanna Creek in the Necanicum River watershed within Seaside city limits in Clatsop County. The culverts to be replaced are juvenile and adult fish passage barriers under certain flow conditions and impair natural channel processes impacting ESA listed coho, Chinook, chum, Pacific lamprey, winter steelhead and cutthroat trout. The project involves three existing, undersized culverts. The project proposes to permanently remove two culverts and relocate the Citys sewer main which currently is installed over the top of the culverts. In addition, the project proposes to replace the existing undersized culvert crossing under Wahanna Road with a 19 open bottom, multiplate arch with natural stream simulation that meets the design criteria of 1.5x active channel width. The project will improve fish access to over one mile of stream habitat and restore full tidal exchange to the sites tidally influenced stream-wetland complex. Project partners include: City of Seaside and Oregon Department of Fish and Wildlife.

The project will improve fish passage to 1.4 miles of spawning and rearing habits for ESA listed Oregon Coast coho salmon, Chinook, chum, winter steelhead, cutthroat trout and Pacific lamprey. In addition, the project will restore channel connectivity between the tidally influenced downstream side of the culvert with the wetlands on the upstream side of the culvert, restoring access to an historic wetland complex and resolving the last fish passage impediment for this productive fish bearing tributary of the Neawanna.