Fish Friendly Culvert Coming to Copper River Highway

Have you noticed a traffic cone on the road shoulder at MP 20.1 on the Copper River Highway?  It’s there to mark a road hazard:  the shoulder is slumping due to road embankment erosion.  This site will be under construction in early to mid-November when the Copper River Watershed Project (CRWP) and its partners — the Alaska Department of Transportation & Public Facilities, Alaska Department of Fish & Game, and the Chugach National Forest — replace the under-sized culvert causing bank erosion with a fish-friendly, stream simulation culvert that will restore fish passage for all life stages of coho and cutthroat trout.

Downstream end of existing culvert.

Downstream end of existing culvert.

In place now is a culvert that is undersized for the width of the stream channel on which it sits — the culvert is just over 5′ wide, while the stream channel is 26′ wide — that’s a lot of water being constricted through a narrow opening, causing streambed scouring and road embankment erosion on the down stream end.  This kind of constriction also imposes a “velocity barrier” on fish, especially juveniles, who can’t swim upstream against such a strong rate of flow.  Juveniles need to be able to move up and down stream freely to search for food, and under-sized culverts that inhibit their movement are effectively limiting salmon population productivity.

Depending on the timing of construction, the Copper River Highway will be closed down to one lane, or possibly closed completely for a short time to keep construction costs to a minimum.  Please contact the Copper River Watershed Project with any questions about this project.

You can find more details about the culvert at this location, and all culverts on the Copper River Highway, at the CRWP’s Culvert Mapper web site.