Culvert Assessment and Recommendations Fish Passage Evaluation Holgate Creek Haines, Alaska
Holgate Creek is a small perennial stream located in Haines, Alaska. Alaska Department of Fish and Game designates the stream as #115-32-094 (One-mile Creek). The stream is a tributary of the Chikat River and joins the Chilkat northwest of Pyramid Island. The stream supports several species of fish, the most abundant being Coho salmon (Onchorhynchus kisutch) and cutthroat trout (Onchorhynchus clarkii). Dolly Varden (Salvelinus malma) as well as sticklebacks and sculpin have also been captured in the stream. Fish passage into the stream may be a limiting factor to fish populations. Several culverts along the stream have been identified as possible barriers limiting fish access to the stream. In 2005-2006 the Takshanuk Watershed Council (TWC) conducted a baseline assessment and monitoring project on Holgate Creek, funded by the US Fish & Wildlife Service (FWS). Their report, “Holgate Creek Assessment and Monitoring Project, December 2006” highlights several issues and opportunities, one being fish passage: Fish passage may be a concern, particularly in times of low flow in the creek. The culvert under Mud Bay Road is considered to be undersized by Fish and Game personnel (Ben Kirkpatrick pers comm.). The current fish ladder was installed as partial compensation for this but the tendency of the cobbles within it to wash out calls into question its effectiveness. Recommendation: Survey these sites and use passage models to determine if they are indeed problems. Approach ADOT and landowners with solutions. As a result of this, TWC under additional funding from FWS hired Natural Channel Design to conduct fish passage evaluation. This assessment focuses on the most downstream culvert which passes under Mud Bay Road at the mouth of Holgate Creek using the following protocols: • Tongass Road Condition Survey Protocol (GREEN-GRAY-RED) • Tier I Stream Simulation Design (MOA between ADFG and ADOT) • Hydraulic/critical velocity Evaluation Adult cutthroat trout and Coho salmon as well as juvenile Coho are the target species for movement into the stream. Fish passage issues generally focus on the ability of returning adult salmonids to migrate upstream to spawning beds during the summer months. However, juvenile Coho have been observed in the stream in the fall and their ability to move up and downstream may also be important. This pattern complicates fish passage considerations. While depth of flow and physical barriers are often the limiting factors for summer returning adult fish, the high flows characteristic of the fall season in this region make culvert flow velocities a critical parameter as well. This report assesses the performance of the existing culvert and provides recommendations to improve fish passage. The culvert was evaluated for the following characteristics. • Sufficient fish passage for returning adult cutthroat and Coho during the summer; • Sufficient fish passage for Coho salmon fry in the fall; • Adequate flood flow conveyance capacity; and • Adverse impacts to stream function.
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