Fish Passage


Salmon migrate from the ocean back to the streams they were born in to spawn. These adult salmon face many barriers to their journey upriver, many of which were caused by humans. Barriers in the form of road culverts, dams, dikes, and other obstructions reduce the area that these fish can access and lay their eggs.  The inability of fish to migrate upstream have eliminated fish populations altogether in some areas.

Most of the barriers to fish passage in Washington State are the result of culverts at private and public road crossings. Over the past several decades, culverts placed in streams were often too small or were improperly installed to allow for the passage of fish. When winter stream flows arrive, the speed of the water through the culverts often exceeds the swimming ability of fish.  In other situations, the downstream end of culverts may be at a higher elevation than the channel and salmon cannot always jump high enough to get into them – this is called a “perched culvert”. In some cases, a culvert may become a barrier because it is clogged or crushed.

Undersized or failing culverts can create problems for property owners too. During storms, water can back up behind the undersized or broken pipe and flood fields and homes and wash out roads and driveways. Broken and clogged pipes can impound water upstream of a culvert and create a pond where one did not previously exist. For an example of this problem, check out the story about the McGillivray family.

Barriers to fish passage are found on both private and public land, and the problem requires participation of local, state and federal agencies, and private landowners. There are resources available to help landowners evaluate and repair or replace crossings that are barriers to fish passage.

The staff at the Snohomish Conservation District can help. Please contact us if you’d like free assistance – we can visit with you at your property to provide advice on your crossing, assist with permitting, and connect you with financial assistance programs through the District or other agencies.
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fish passage_before
Fish passage (before)


fish passage_after
Fish passage (after)



A perched culvert


Two other resources are available to help property owners with road crossings and fish passage barriers are: