EPA's Vessel General Permit and Small Vessel General

Status and Trends
NMFS originally listed Snake River fall-run Chinook salmon as endangered in 1992 (57 FR
14653) but reclassified their status as threatened on June 28, 2005 (70 FR 37160). Estimated
annual returns for the period 1938 to 1949 was 72,000 fish, and by the 1950s, numbers had
declined to an annual average of 29,000 fish (Bjornn and Horner 1980). Numbers of Snake
River fall-run Chinook salmon continued to decline during the 1960s and 1970s as
approximately 80% of their historic habitat was eliminated or severely degraded by the
construction of the Hells Canyon complex (1958 to 1967) and the lower Snake River dams (1961
to 1975). Counts of natural-origin adult Snake River fall-run Chinook salmon at Lower Granite
Dam were 1,000 fish in 1975, and ranged from 78 to 905 fish (with an average of 489 fish) over
the ensuing 25-year period (Good et al. 2005). Numbers of natural-origin Snake River fall-run
Chinook salmon have increased over the last few years, with estimates at Lower Granite Dam of
2,652 fish in 2001, 2,095 fish in 2002, and 3,895 fish in 2003.
Snake River fall-run Chinook salmon have exhibited an upward trend in returns over Lower
Granite Dam since the mid 1990s. Returns classified as natural-origin spawners exceeded 2,600
fish in 2001, compared to a 1997 to 2001 geometric mean natural-origin count of 871 (35% of
the proposed delisting abundance criteria of 2,500 natural spawners averaged over 8 years).
Both the long- and short-term trends in natural returns are positive. Harvest impacts on Snake
River fall Chinook salmon declined after listing and have remained relatively constant in recent
years. Mainstem conditions for sub-yearling Chinook migrants from the Snake River have
generally improved since the early 1990s. The hatchery component, derived from outside the
basin, has decreased as a percentage of the run at Lower Granite Dam from the 1998/99 status
reviews (5-year average of 26.2%) to 2001 (8%). This reflects an increase in the Lyons Ferry
component, systematic removal of marked hatchery fish at the Lower Granite trap, and
modifications to the Umatilla supplementation program to increase homing of fall Chinook
salmon release groups. Hatcheries stocking fish to the Snake River fall run produce genetic
affects in the population due to three major components: natural-origin fish (which may be
progeny of hatchery fish), returns of Snake River fish from the Lyons Ferry Hatchery program,
and strays from hatchery programs outside the Snake River.
Critical Habitat
NMFS designated critical habitat for Snake River fall-run Chinook salmon on December 28,
1993 (58 FR 68543). This critical habitat encompasses the waters, waterway bottoms, and
adjacent riparian zones of specified lakes and river reaches in the Columbia River that are or
were accessible to listed Snake River salmon (except reaches above impassable natural falls, and
Dworshak and Hells Canyon Dams). These areas are important for the species’ overall
conservation by protecting quality growth, reproduction, and feeding. Adjacent riparian zones
are defined as those areas within a horizontal distance of 300 feet from the normal line of high
water of a stream channel or from the shoreline of a standing body of water. Designated critical
habitat includes the Columbia River from a straight line connecting the west end of the Clatsop
jetty (Oregon side) and the west end of the Peacock jetty (Washington side) and including all
river reaches from the estuary upstream to the confluence of the Snake River, and all Snake
River reaches upstream to Hells Canyon Dam. Critical habitat also includes several river reaches
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