• Most recent research on how salmon use the estuary and how restoration can benefit

    September 2013: BPA and the Corps of Engineers have released a new report compiling findings about the benefits of estuary habitat restoration. Click here to view the report. 

    The Columbia River estuary refers to the roughly the 150 miles (240 kilometers) of the Columbia River below Bonneville Dam that is subject to tidal influence, including both freshwater and salinity-influenced areas.


    Columbia Basin salmon and steelhead spend anywhere from days to months in the estuary before entering the ocean. The rising attention to the lower river and estuary has been supported by an expanding body of research demonstrating the ecological importance of these habitats to salmon and steelhead and informed biological opinions for ESA-listed fish affected by operation of the FCRPS dams.

    In the first phase of a multi-year project, partners removed a tide gate and re-opened wetlands in Sauvie Island's Ruby Lake, outside of Portland, Oregon. The project restored more than 123 acres of historic juvenile salmon and steelhead habitat.  


    Rehabilitated estuary wetlands are highly productive, producing large amounts of organic matter and insect prey for salmon. Increased feeding by salmon and steelhead in the estuary can fuel rapid growth, in some cases exceeding 1 millimeter per day, as fish gain size quickly before entering the ocean. Studies indicate that faster growing and larger juvenile Chinook salmon are better positioned to survive the first year in the ocean, when most salmon are believed to perish. 





    Research suggests that salmon select food from food webs linked to plant and animal organisms found in wetland habitats such as those in the estuary. Sampling of stomach contents of juvenile salmon and steelhead at three sites on their downstream migration indicated that their stomachs were substantially more full after transiting the estuary.  

    Before this culvert was installed near Fort Columbia State Park in 2011, no fish were found in the wetland adjacent and fewer than fiver salmon were caught along the shore of the estuary nearby. (CREST 2011).

    A month after it was installed, researcher found 20 chinook and one coho salmon in the wetland. In the estuary just outside the newly installed culvert, they saw exponentially more juvenile salmon, indicating more fish were drawn to the site. 




  • Diversity and estuary survival

    “The estuary has come to be regarded as part of the continuum of ecosystems that salmon need to utilize to complete their life cycle, rather than a place that salmon need to avoid.” Fresh et al. (2005)



    Some of the most important research on salmon in the estuary (Rich 1920, Rich 1939) took place in the Columbia River system in the early 1900s, although its significance was not widely recognized until decades later. Willis Rich’s studies of Chinook salmon found juvenile fish traveling through and feeding in the estuary throughout the year. He also found that their scale patterns showed significant growth in the estuary, indicating that they use the estuary more than once thought.



    Rich’s continued research demonstrated that Columbia Basin salmon populations spread out and use different parts of the estuary, in different ways, at different times, allowing for millions of fish to benefit from its diverse habitats.

    Read more on habitat and fish

    Find out about the science of tributary habitat restoration in this report:


    Benefits of tributary habitat improvements in the Columbia Basin



    Find out more about how habitat projects are selected and evaluated in these informative guides:

    q Science and the evaluation of habitat restoration projects in the Columbia River estuary


    q Science and the evaluation of habitat improvement projects in Columbia River tributaries


    Learn more in the 2016 Citizen's Guide.

    Citizen's Guide cover page