Fish Passage - Why are we fixing barriers?

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A single removed barrier can deliver impressive benefits, improving fish access for miles both upstream and downstream. When rivers and streams are connected, fish can better access the habitat they need. This is an important component of protecting and restoring fish populations, which can in turn have multiple benefits - including for commercial and recreational fishing industries.

Why does WSDOT have barrier culverts?

Most of the culverts were installed decades before scientists fully understood the needs of fish. WSDOT met all requirements for culvert installation and sizing at the time they were constructed. Also, a culvert that was fish passable at the time of installation might have become a barrier over time due to changes in the landscape resulting from development, logging and fire. The new fish-friendly structures WSDOT constructs now are much larger and should be more resilient to changes in the landscape and provide for fish passage long into the future.

Before Photo

This 2.5 foot diameter culvert on State Route 203 Langlois Creek was a partial barrier to fish due to excessive velocities. The old culvert was nearing the end of its useful life and starting to deteriorate.

This 2.5 foot diameter culvert on State Route 203 Langlois Creek was a partial barrier to fish due to excessive velocities.  The old culvert was nearing the end of its useful life and starting to deteriorate.

After Photo

WSDOT replaced the State Route 203 Langlois Creek culvert in 2018, improving access to 5.4 miles of upstream habitat to chum, Chinook, steelhead, and trout.

WSDOT replaced the State Route Langlois Creek culvert in 2018, improving access to 5.4 miles of upstream habitat to chum, Chinook, steelhead, and trout.  WSDOT partnered with Wild Fish Conservatory on additional stream habitat restoration upstream and downstream of State Route 203.

Number of Fish Barriers

  • Approximately 2,027 culverts are barriers to fish passage on the statewide highway system.
  • Of that total, about 1,504 are fish passage barriers that have more than 200 meters of upstream habitat.
  • As of 2019, WSDOT completed 345 fish passage projects statewide and improved access to about 1,155 miles of potential habitat upstream.

How do we know it’s working?

Biologists monitor many of our fish passage barrier corrections to ensure they’re functioning to provide fish passage. In many cases, fish are detected upstream of projects immediately after construction. See our latest Fish Passage Annual Report (pdf 8.4 mb).