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Fish Passage Restoration Program

Fish Passage Restoration Program

Opening the best habitat to the most salmon as quickly as possible

Surveying the elevation of a culvert inlet

One of the most effective ways to ensuring the survival of native salmon – and the southern resident orcas that rely on them as a food source – is to remove barriers to their habitat.

We’re working with our partners to remove barriers to habitat that exist on land where we are the stewards, which includes replacing culverts that were built under county-owned roads and trails but now block salmon from swimming upstream.

Under the direction of King County Executive Dow Constantine, we’ve increased funding to support work by county divisions – Water and Land Resources, Parks, Roads, and Permitting – to restore access to high-quality habitat at a faster pace. We’re also improving the planning, design, and construction of projects to improve the final project and get projects built absolutely as fast as possible. Yet we must accelerate our efforts before it is too late for native salmon populations that have been important to the way of life here since time immemorial.


Work to remove barriers to fish passage

Working to fix fish passage barriers

The King County Fish Passage Restoration Program provides a roadmap to success, which will require a regional approach, strong partnerships, enough funding, and a flexible permitting process. Building on a 2021 report (see link below), King County scientists and engineers have identified the best stream locations to remove barriers that prevent salmon from swimming to high-quality habitat.

The report recommendations are based, in part, on a comprehensive inventory of more than 3,000 sites along county-owned roads and trails and on county property that are potential barriers to upstream habitat.

Most of the barriers to salmon habitat are metal or concrete pipes, known as culverts, that were installed below roads, trails, and railroads since the 19th century so that streams could flow underneath. Unfortunately, many of the older culverts are so long, straight, and steep that they prevent fish from swimming through them.

In many cases, the culverts resemble firehoses, pushing water at a high velocity and making it nearly impossible for salmon to swim through. In other cases, the flows from the culvert over time erode a deep hole in the streambed downstream, preventing fish from being able to jump high enough into the culvert so they can continue to swim further upstream.

Modern culverts are designed more like arches than pipes, built so that streams can flow naturally underneath roads and trails with no barriers for salmon.

A before and after illustration. The before side shows salmon unable to complete their migration due to an inaccessible pipe culvert blocking the way. The after side shows a new wide box culvert that allows for the fish to access their historic habitat.

Prioritizing which barriers to remove first to achieve the best results

Using data from the inventory and assessment of county stream crossings, we’ve worked with Tribes, federal and state agencies, and cities to develop a methodology that prioritizes which barriers should be removed first to achieve the best results for fish.

Our data analysis considers both the quality and the amount of fish habitat that could be restored if a specific barrier is removed.

Focusing county work on restoring fish passage at the barriers that block the most and best habitat can vastly increase the amount of habitat opened up in the next 30 years. Analysis indicates that correcting the barriers that block the most habitat first can provide many times the habitat gain compared to removing barriers in a random order.

The field team of experts inspected more than 3,000 locations where habitat is possibly blocked by county-owned roads and trails. They ranked more than 700 of the identified barriers and determined that completing 50 restoration projects would restore access to at least half of the habitat that is currently blocked by county structures that block salmon from swimming upstream. The county is developing plans to complete this work in the next 10 years.

Over the longer term, the prioritization work estimates that restoration of fish passage at about 150 of the top priority county barriers could restore salmon access to at least 90 percent of the habitat that’s currently blocked.

King County fish passage map
Spawning sockeye salmon

Early action to produce results sooner

Starting in the 2019-2020 budget and continuing into the budget for 2021-2022, Executive Constantine has directed more than $20 million to move forward on dozens of projects that will connect to salmon to more than 150 miles of high-quality habitat. In addition to planning and design work on many projects, the county plans to complete construction that restores fish passage at 16 barriers between 2019 and the end of 2022.

The evolving 10-year work plan for fish passage estimates that restoring salmon access to at least half of the habitat currently blocked by county barriers will require an investment of about $150 million.

Key to the effort will be work to get the most habitat value from investments in fish passage. This includes taking advantage of innovative methods and opportunities to standardize common tasks and designs. We’re also exploring options to close the gap between the current funding and the amount of funding we’ll need. Possible funding and financing options include:

  • Maximizing grant funding;
  • Regulatory flexibility to allow transfer of limited public funding to high priority fish passage restoration projects when repairing or replacing barrier culverts with little upstream salmon habitat;
  • Public-private partnerships; and
  • Public funding options like future levy proposals and bonds that require voter approval.

The inventory and prioritization will make King County highly competitive for local, state, and federal grants – including the federal Bipartisan Infrastructure Bill – that fund projects to restore access to high-quality habitat, which is critical to the survival of native salmon and southern resident orcas that rely on them as a food source.

Read the reports

Related information

Clean Water Healthy Habitat
Clean Water Healthy Habitat
The right investments at the right time in the right places.

For more information about the Fish Passage Restoration Program, please contact
Evan Lewis, Water and Land Resources Division.

Fish Passage Restoration Program

Evan Lewis