West Fork Environmental recently concluded two studies on the passage of resident coastal cutthroat trout through corrugated metal culverts. This research was conducted at the culvert test bed facility located at the Skookumchuck fish hatchery operated by WDFW. The passage trials utilized wild cutthroat trout from tributaries of the upper Skookumchuck River and were funded primarily by the National Council for Air and Stream Improvement (NCASI).
Our ability to control velocity, outfall drop and tailwater pool conditions permitted us to experimentally assess the dual influences of drop height and water velocity on the ability of fish to successfully enter and pass through the test culvert. Information from these studies is currently being validated using field trials to test passage of coastal cutthroat trout at culverts with drop heights and velocities similar to those tested at the culvert test bed facility.
This research will add to the growing body of literature that addresses the question of passage, partial passage and fragmentation for resident trout populations inhabiting headwater streams.