Coho Salmon

Coho smolt

Coho smolt captured and released for a research project.

The coho salmon (Oncorhynchus kisutch) is one of the most popular sport fishes in the family Salmonidae. For most of the twentieth century, it has been the mainstay of the average west coast salmon sport fishing trip. Coho salmon occur along the Pacific coast from Monterey Bay, California, northward to Point Hope, Alaska. The typical size of adult coho salmon in the Lake Washington basin is between 4 and 7 pounds when they typically return to spawn as 3-year old fish. Read more about coho salmon life history and ecology on the Seattle Public Utilities Cedar River Biodiversity website.

The population of coho salmon in the Cedar River is thought to be somewhat unique and is defined by the timing of their spawning (late October to late February) as well as their geographic separation from other significant coho streams in the drainage. The coho population in the Lake Washington watershed is comprised of both natural and hatchery subpopulations. Significant releases of hatchery yearlings were made from the early 1950s to the early 1970s, and regular fingerling and fry plants were made from the mid-1970s to the present.

Coho salmon are typically thought to favor small tributaries for spawning and juvenile rearing, however, substantial coho spawning and rearing has been observed in the mainstem Cedar River. Cedar River coho incubate throughout the winter and early spring and are thought to complete emergence from the gravel by early June. Young coho typically rear for approximately 1 year in the Cedar system prior to migrating downstream to the marine environment.


Our long term goal for coho is to increase the population from current levels. Our specific objectives include:

  1. Protecting water quality through habitat protection measures in the Cedar River watershed
  2. Provide appropriate flows to support coho during river residence
  3. Increasing the amount of high quality habitat available to coho by opening access to twelve miles of mainstem habitat and five miles of tributary habitat above Landsburg Dam
  4. Acquiring and protecting property adjacent to the Cedar River below Landsburg Dam to reduce the impact of development activities on conditions in this area


What are we doing for coho salmon?

Watershed management practices in the municipal watershed between Masonry Dam and Landsburg protect water quality, aquatic, riparian and upland habitats and the processes that create and maintain a healthy river.

Construct and operate fish passage facilities at the Landsburg diversion dam to restore fish access to over 20 miles of stream habitat in the protected municipal watershed for the first time since 1901.

Instream flow management practices to promote a healthy river and provide beneficial habitat conditions for all life stages of Chinook salmon. .

Downstream habitat protection and restoration along the 22 miles of river below Seattle’s municipal watershed to support flood plain management practices that help create and maintain beneficial habitat conditions throughout the lower river.