Indian Creek Culvert Replacement & Fish Passage, Washington

Two culverts through the Indian Creek road embankment had been barriers to fish passage to upstream habitats along Indian Creek. With removal of the Condit Dam on the White Salmon River, salmon, steelhead and coastal cutthroat trout can now swim up Indian Creek and access habitats upstream of the project. In early 2010, Underwood Conservation District contracted the team of Inter-Fluve and Tenneson Engineering to conduct site investigations, perform an alternatives analysis, and prepare designs and construction documents of a preferred alternative.

As the prime consultant, Inter-Fluve was responsible for stream analysis and design, as well as selecting a road crossing structure. A number of alternatives were considered including bottom-less large pipe arch or box culverts and a modular pre-cast concrete bridge. From a cost-benefit analysis, a modular pre-cast concrete bridge manufactured by Pacific Bridge and Construction was selected. Inter-Fluve designed the bridge open area required for stream processes, depth of abutments, scour protection and roughened channel for fish passage along the stream.