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Whatcom County Fish Passage Barrier Inventory

Human made barriers such as road culverts, tide gates, and dams prevent fish, including endangered and threatened salmon runs, from accessing over 600 miles of stream habitat in Whatcom County. Removing these barriers is one of the easiest and most cost-effective means for improving fish habitat.

Culverts are often used to route streams under roads, railroad beds, or levees and dikes, and make up roughly 90% of the human made barriers to fish. If a culvert isn’t properly constructed or maintained, it can block fish from traveling upstream. Culverts can pose a variety of problems for fish:

• Perched culvert. When a culvert is perched, its downstream end is higher than the water level. Fish have difficulty jumping up to the culvert and may not be able to get through.
• Size. Some culverts are too small for fish to swim through.
• Increased water velocity. If a culvert is too steeply pitched, or is too small to convey the winter flow volume, it may increase a creek’s velocity to the point where fish cannot swim quickly enough to pass through the culvert.
• Maintenance. If a culvert is not cleaned out regularly, it may become clogged, which can prevent fish from passing through.
  To help identify and fix culverts and other barriers to fish passage in the county, Whatcom County Public Works secured a $708,000 grant from the state Salmon Recovery Funding Board to inventory fish passage barriers on public and private lands in western Whatcom County, and then prepare the top 20 priority barriers for repair.

The inventory assessed in-stream features and identified fish passage barriers, determined the amount of blocked habitat above each barrier, and used this information to prioritized these barriers for replacement. Western Whatcom County was divided into 10 sub-basins which were ranked based on priority fish species and habitat. The inventory began in the highest-priority sub-basin, the South Fork Nooksack, and proceeded down the priority list. This allowed replacement work to begin in high-priority basins without waiting for the entire inventory to be completed.

Work on the inventory of County roads began in 2000. To date, the overall inventory has identified approximately 500 barriers that block fish passage either completely or at high flows. The current grant began in June 2002, with the final comprehensive inventory products and priority barrier designs due by the end of 2006.

Final Report and Appendix A: Outreach Examples
Appendix B: South Fork Nooksack Sub-basin Report
Appendix C: Middle Fork Nooksack Sub-basin Report
Appendix D: North Fork Nooksack Sub-basin Report
Appendix E: Deming Sub-basin Report
Appendix F: Sumas Sub-basin Report
Appendix G: Lynden Sub-basin Report
Appendix H: Tenmile Sub-basin Report
Appendix I: Coastal Sub-basin Report
Appendix J: Chuckanut Foothills Sub-basin Report
Appendix K: Samish Sub-basin Report
ArcView shape files

(77.45MB) Complete Report, including appendices

For more information about other habitat problems, see the Habitat page.

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