Restoring Fish Passage








Fish Passage Mitigation Banking

Reopening Oregon rivers for migrating fish



We helped Oregon become the first state to create a mitigation bank to meet fish passage requirements. With limited public funding available to address Oregon’s significant river restoration needs, fish passage mitigation banking has the potential to draw in millions of dollars for tackling the state’s greatest barriers to migrating fish, like salmon and steelhead. With our partners, we helped to reopen over 20 miles of salmon habitat on the Trask River by removing the largest barrier to fish in the North Coast district. Watch a time-lapse video of the dam removal and learn more about fish passage mitigation banking below.



Video / Oregon Department of Forestry

Reopening the Trask River to migrating salmon


Fish passage mitigation banking allows developers to meet the legal requirements for offsetting the impact of their construction projects by investing in the removal of high-priority barriers in streams that block migrating fish from accessing miles of high-quality habitat upstream.

In 2016, the Oregon Department of Fish and Wildlife partnered with the Oregon Department of Transportation, Willamette Partnership, and The Nature Conservancy to test this approach in order to help advance and accelerate high-priority river restoration projects for native migratory fish like salmon and steelhead. We helped develop the fish passage calculator to provide state agencies with a scientifically defensible way of determining where river restoration projects could benefit migrating fish the most. As a pilot application of this approach to mitigation, a dam was removed on the Trask River of Oregon’s North Coast Basin, reopening of 23 miles of habitat for salmon to migrate.


In Oregon, it is law to provide a way for fish to get around artificial obstructions where native migratory fish are present. There is, however, a caveat. Developers can apply for a waiver to mitigate their impacts instead if the mitigation project will help out more native migratory fish in the end. In other words, if you’re building a road across a stream you either have to provide a way for fish to get around the road or you have to improve passage elsewhere that’s going to help out more fish than your project is affecting.

With a fish passage bank, Oregon Department of Fish and Wildlife can make more transparent and data-driven decisions about which mitigation projects are acceptable in lieu of providing fish passage.

In the case of the fish passage bank on the Trask, access to 23 miles of high-quality habitat for native migratory fish was gained in exchange for waiving eight to 13 culvert maintenance projects with less than 0.5 miles of low- to moderate-quality habitat upstream of each culvert.


(Download the fish passage fact sheet)


“This process will allow ODOT to make vital culvert repairs and replacements while providing an increased net-benefit to native migratory fish over the existing waiver [mitigation] process.”


– Bill Warncke, Statewide Aquatic Biology & Fish Passage Program Leader, Oregon Department of Transportation


At the end of the pilot phase (2015-2018), Oregon Department of Fish and Wildlife will be evaluating its success and lessons learned to potentially develop a statewide mitigation banking program for the state of Oregon.

Learn more about how fish passage mitigation banking and the credit calculator work.

fish passage trask river willamette partnership graphic

Photos courtesy of Oregon Department of Transportation

Get in touch about fish passage.


Nicole Maness


Have questions about the country’s first fish passage mitigation banking program?

Contact Nicole Maness, Partner, Resilient Habitat
email |
office | 503.542.4304

We helped develop habitat mitigation programs for states across the West to protect greater sage-grouse and give ranchers an economic boost.