Coho Creek Culvert Replacement (NEW)
Fish Passage and Screening
Client / Agency
U.S. Fish & Wildlife Service
Necanicum Watershed Council, Oregon Department of Fish and Wildlife
2011 - 2013
River Design Group, Inc. (RDG) was retained by the U.S. Fish & Wildlife Service (USFWS) and the Necanicum Watershed Council to complete a fish passage alternatives analysis for Spruce Loop Road in Seaside, Oregon. Spruce Loop Road crosses Coho Creek and provides access to Seaside Elementary School. The existing culvert was a barrier to migrating fish because of a 2 ft perch at the downstream outlet, water velocities in the culvert that exceed fish swimming abilities, and water depths within the culvert that are insufficient for fish to swim. Fish species inhabiting Coho Creek include coho and fall Chinook salmon, winter steelhead, and coastal cutthroat trout. Approximately one mile of stream channel located upstream from the culvert would be made accessible with the culvert replacement. Additionally, the existing culvert is at the end of its service life and portions of the pipe have rusted through, allowing the culvert to be undermined by stream flow. The culvert was slip-lined using corrugated plastic pipe in 2011, however the repair was only partially effective and additional repairs were performed in November 2011.
The alternatives analysis included a pipe arch culvert, an open-bottom arch, and a bridge. The open-bottom arch was selected as the preferred alternative by the project stakeholders. RDG completed a final design, provided permitting support, and oversaw project implementation in 2013.