EPA's Vessel General Permit and Small Vessel General

White Salmon River and Deschutes Crooked River above the Pelton/Round Butte Dam complex.
Present population structure is delineated largely on the basis of geographical proximity,
topography, distance, ecological similarities or differences. Additional genetic studies are
needed to describe the DPS substructure, as well as the fine-scale genetic structure of the
populations within a particular basin (e.g., John Day River).
Most Middle Columbia River steelhead smolt at 2 years of age and spend 1 to 2 years at sea prior
to re-entering natal river systems. They may remain in such rivers for up to a year prior to
spawning (Howell et al. 1985b). Factors contributing to the decline of Middle Columbia river
steelhead include hydropower development and agriculture; these land uses impede or prevent
migrations, alter water availability, and alter water chemistry and temperatures.
Status and Trends
Middle Columbia River steelhead were listed as threatened in 1999 (64 FR 14517), and their
status was reaffirmed on January 5, 2006 (71 FR 834). The precise pre-1960 abundance of this
species is unknown. Based upon the Washington Department of Fish and Wildlife’s estimates of
the historic run size for the Yakima River at 100,000 steelhead, Busby et al., (1996) surmised
that total DPS abundance likely exceeded 300,000 returning adults. By 1993, the estimated 5year
average size (ending in 1993) of the Middle Columbia steelhead DPS was 142,000 fish
(Busby et al. 1996). Survey data collected between 1997 and 2001 indicates that several
populations within the DPS have increased since the last status review (Good et al. 2005).
However, long-term annual population growth rate (λ) is negative for most populations.
In contrast, short term trends in major areas were positive for 7 of the 12 areas with available
data (see Good et al., 2005). Spawner numbers in the Yakima River, the Deschutes River and
sections of the John Day River system were substantially higher compared to numbers surveyed
between 1992 and 1997 (Good et al. 2005). Similarly, spawner numbers substantially increased
in the Umatilla River and Fifteen-mile Creek relative to annual levels in the early 1990s.
Nonetheless, most populations remain below interim target levels. For instance, the Yakima
River returns are still substantially below interim target levels of 8,900 (the current 5-year
average is 1,747 fish) and estimated historical return levels. In fact, the majority of spawning
occurs in only one tributary, Satus Creek (Berg 2001as cited in Good et al., 2005). Based on
recent 5-year geometric means, only the Deschutes River exceeded interim target levels (Good et
al. 2005). While increases in short-term trends could suggest improvements within the DPS,
given that the average population growth rate across all streams is negative (0.98 assuming
hatchery spawners do not contribute to production, and 0.97 assuming that both hatchery and
natural-origin fish contribute equally) and evidence of large fluctuation in marine survival for the
species, recent increases in population sizes must be viewed cautiously (Good et al. 2005).
Critical Habitat
NMFS designated critical habitat for Middle Columbia River steelhead on September 2, 2005
(70 FR 52630). Designated critical habitat includes the following subbasins: Upper Yakima,
Naches, Lower Yakima, Middle Columbia/Lake Wallula, Walla Walla, Umatilla, Middle
Columbia/Hood, Klickitat, Upper John Day, North Fork John Day, Middle Fork John Day,
Lower John Day, Lower Deschutes, Trout, and the Upper Columbia/Priest Rapids subbasins, and
the Columbia River corridor. These areas are important for the species’ overall conservation by
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