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Fish Passage - Problem and solution

WSDOT- Redrawn from Fish Passage Short Course, John RunyonFish Passage cartoon depicting challenges for fish

What is a fish barrier?
A fish passage barrier is anything that hinders any life stage of fish from moving through a waterway. Culverts, which are generally large pipes beneath roadways, may allow water to flow but not provide conditions that fish can swim through. The water that flows through culverts may block fish migration because the flow is too swift, too shallow, or has a waterfall into or out of the culvert.

What is the solution?

In the 2017-19 biennium, approximately $97.5 million will be spent on stand-alone projects that correct fish passage barriers. In addition to these projects, other larger highway projects will correct barriers that are within the boundaries of those projects. See more detailed numbers in our Six Year Project Plan.

Making culverts fish-passable involves much more than simple replacement. The recent federal court injunction is not about replacement per se. Rather, it requires that fish passage be achieved (in order of preference) by:

  1. Avoiding the necessity for the roadway to cross the stream
  2. Using a full span bridge
  3. Using a “stream simulation” methodology

Whenever possible, WSDOT will work with owners of adjacent barriers to coordinate barrier corrections. Partnerships such as this are key to the success of WSDOT's Fish Passage program.