Lake Washington

Lake Washington forms an especially interesting link in the salmon life history chain. It provides opportunities for some species and potential challenges for others.

Lake Washington Shoreline

Young coho salmon and steelhead may be challenged by the need to migrate through a large lake during their emigration to the ocean. However, these species are relatively large when they migrate and they seem to migrate through Lake Washington with some success.

On the other hand, Lake Washington juvenile chinook salmon migrate as much younger fish and are smaller than juvenile coho or steelhead. Young chinook may be challenged by their long migration through the still water of the lake. Researchers are currently studying the ability of young chinook to use the near-shore areas of the lake as rearing grounds where they may grow prior to migration and thus improve their chances of survival.

In contrast to chinook, coho and steelhead that tend to use just the near-shore areas of the lake, juvenile sockeye salmon are uniquely adapted to use the extensive deep water areas of the lake. Here sockeye rear and grow for approximately 1 year prior to migrating to sea. Throughout the range of pacific salmon, sockeye are typically the dominant species in systems with large natural lakes located immediately downstream from major spawning areas. This general pattern is clearly evident in the Lake Washington basin where sockeye are by far the most abundant salmon species.

Lake Washington is greatly changed from its original state. Between 1912 and 1917, the outlet from the lake was changed from its original location which drained out the south end of the lake into the Black River to its present location through the Lake Washington Ship Canal and the Ballard Locks on the west side of the lake. In addition, the Cedar River, which previously flowed into the Black River downstream of the lake, was rerouted into Lake Washington.

This rerouting doubled water flow into the lake and created a whole new pathway for salmon returning to and leaving from the Cedar River; the largest salmon producing stream in the basin. This alteration dramatically changed the ecology of the system for Cedar River salmon, creating a new opportunity for sockeye and new challenges for the other species.

In addition to the reconfiguration of basic system plumbing, development and urbanization have had substantial effects on the lake. A number of exotic fish species, some of which prey on young salmon, have also been introduced into the system and appear to be thriving. The effects of all these actions on salmon are not well understood. And while salmon appear to perform relatively well in some years, in many years they do not.

The headwaters protection and restoration measures provided by the Cedar River Watershed HCP, combined with the plan's instream flow management regime help ensure that sufficient amounts of high quality water will be delivered to Lake Washington. In addition, the HCP provides financial support for lake studies that will help us better understand the factors affecting the survival of young sockeye in the lake. The HCP measures are linked with broader lake research and conservation efforts sponsored by King County, the University of Washington, and local municipal governments.

These programs are working to help us to:

  • Better understand the physical, chemical and biological processes in the lake and their relationship to salmon populations.
  • Protect water quality and fish habitat in the lake.
  • Increase opportunities for regional cooperation and coordination of local, state, tribal and federal salmon recovery efforts.

Contact Information

For additional information about HCP implementation, please contact:
Michele Koehler, Aquatic Resources & HCP Program Manager
(206) 733-9447
michele.koehler@seattle.gov