Overview:  According to studies conducted by NMFS (National Marine Fisheries Service) there are five population groups or ESU (Evolutionary Significant Units) of steelhead salmon remaining within Washington State.  Of these 5, the Upper Columbia River ESU (from the Yakima River upstream to Chief Joseph Dam) and the Snake River Basin ESU (encompassing parts of Idaho, Washington, and Oregon) were both listed on August 11, 1997.  The Snake River ESU was listed as Threatened and the Upper Columbia ESU was listed as Endangered.  Recently, the Middle Columbia River ESU (encompassing the Yakima, Walla Walla, Umatilla, John Day and Deschutes river basins) also joined these populations when it was listed as Threatened in March of 1998.  As a species, steelhead differ from their other salmonid populations in a couple of interesting ways.  First, this species spends more of its lifetime in freshwater than any other salmonid species.  Secondly, what makes this species unique is that it usually does not die after spawning.  Currently, according to NMFS estimates, steelhead populations within Washington State are declining.  Specifically, recent estimates for average adult abundance within the Yakima, Walla Walla, Umatilla, John Day, and Deschutes river basins combined has been estimated at 13,400 adults (compared to a historical run size estimate of 100,000 fish in the Yakima River alone).  In the next year, NMFS will be conducting more extensive research on these populations and will release final critical habitat designations for all of Washington's ESUs by March 2000.  For more information on steelhead populations check out NMFS’ page @ http://www.nwr.noaa.gov/1salmon/salmesa/index.htm.

Distribution:  Of all the salmonid populations within Washington State, steelhead salmon spend the largest amount of their lives actually within the inland boundaries of the state.  Because of its natural history, this species is found much of the year throughout most of the waterways in Washington.  As displayed in these distribution maps, winter runs are normally found in the Puget Sound region with only a few populations traveling east if the Cascades via the Columbia River.  Contrarily, the summer runs travel much farther and are found throughout the state's major river systems.