EPA's Vessel General Permit and Small Vessel General

FR 24049). The designation encompasses accessible reaches of all rivers (including estuarine
areas and riverine reaches) between Punta Gorda and the San Lorenzo River (inclusive) in
California, including two streams entering San Francisco Bay: Arroyo Corte Madera Del
Presidio and Corte Madera Creek. This critical habitat designation includes all waterways,
substrate and adjacent riparian zones of estuarine and riverine reaches (including off-channel
habitats) below longstanding naturally impassable barriers (i.e. natural waterfalls in existence for
at least several hundred years). These areas are important for the species’ overall conservation
by protecting growth, reproduction, and feeding.
Lower Columbia River Coho Salmon
Distribution and Description of the Listed Species
The lower Columbia River coho salmon ESU includes all naturally spawned populations of coho
salmon in the Columbia River and its tributaries in Washington and Oregon, from the mouth of
the Columbia up to and including the Big White Salmon and Hood Rivers, and includes the
Willamette River to Willamette Falls, Oregon, Twenty-five artificial propagation programs are
part of this ESU.
Two distinct runs distinguished by the timing of adult returns to fresh water (early returners and
later returners) occur within the ESU. Early returning adults generally migrate south of the
Columbia River once they reach the ocean, returning to fresh water in mid-August and to
spawning tributaries in early September. Peak spawning of early returning adults occurs from
mid-October to early November. Late returning adult coho salmon exhibit a northern oceanic
distribution, return to the Columbia River from late September through December and enter
tributaries from October through January. Most late return adults spawn between November
through January, although some spawn in February and as late as March (Sandercock 1991).
Almost all Lower Columbia River ESU coho salmon females and most males spawn at 3 years of
age.
Status and Trends
NMFS listed Lower Columbia River coho salmon as threatened on June 28, 2005 (70 FR 37160).
The vast majority (over 90%) of the historic population in the Lower Columbia River coho
salmon ESU appear to be either extirpated or nearly so.
Only two populations of coho salmon within this ESU produce a sizeable number of naturally
spawned fish, the upper Sandy River population above Marmot Dam and the Clackamas River
population above the North Fork Dam. Most of the other populations are believed to have very
little, if any, natural production. The long-term and short-term trends for Marmot Dam counts
are both negative. The long-term median growth rate is slightly positive for both the Sandy and
Clackamas rivers, but the confidence intervals for each are very wide indicating there is a large
amount of uncertainty. Both populations within the Sandy and Clackamas rivers have suffered
from recruitment failure a number of times over the past 15 years, despite the reductions in
harvest. The most serious threat facing this ESU is the scarcity of naturally-produced spawners,
with attendant risks associated with small populations, loss of diversity, and fragmentation and
isolation of the remaining naturally-produced fish. Spatial structure has been substantially
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