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Carcasses of coho salmon blocked by a barrier culvert |
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Fish and other aquatic organisms are an important part of Pacific Northwest ecosystems. There are countless streams, rivers, lakes, marshes, and marine waterways in Washington State, supporting diverse varieties of birds, mammals, fish, and other organisms. What’s more, aquatic ecosystems support many sport and commercial industries, which provides jobs, adventure, and sustainable food resources. In order to maintain these essential aquatic resources, the habitat that sustains them must not be blocked, especially for fish in stream environments.
Barriers to fish passage, in the form of road culverts, dams, dikes, and other obstructions, reduces the distribution and habitat available to fish, including salmon and steelhead. In particular, the inability of fish to access upstream spawning and rearing areas results in decreased production and in some cases can eliminate fish populations altogether. WDFW estimates that there are more than 30,000 fish passage barriers in Washington State, with the most common type of barrier being road culverts. In recent decades, culverts placed in streams were often undersized and improperly installed to allow for the upstream passage of fish. When winter stream flow sweeps through these culverts, the speed of the water often exceeds the swimming ability of fish. In many cases, culverts were perched above the stream, causing waterfalls to spill out of the culverts that exceeded the jumping ability of fish.
The abundance of fish passage barriers in the state cannot be corrected without partnerships with other state and federal agencies, local governments, Indian Tribes, Regional Fisheries Enhancement Groups, Lead Entities, private citizens, and others. For this reason, WDFW has developed guidance documents for the inventory, assessment, and prioritization of fish passage barriers and for the design of road culverts for fish passage. Additionally, biological and engineering assistance may be available from WDFW to help assess and review new and replacement fish passage structures.
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