EPA's Vessel General Permit and Small Vessel General

This species was listed because dams isolate them from most of their historic spawning habitat
and the habitat remaining to them is degraded. Historically, spring-run Chinook salmon were
predominant throughout the Central Valley occupying the upper and middle reaches (1,000 to
6,000 feet) of the San Joaquin, American, Yuba, Feather, Sacramento, McCloud and Pit Rivers,
with smaller populations in most tributaries with sufficient habitat for over-summering adults
(Stone 1874, Clark 1929).
The Central Valley drainage as a whole is estimated to have supported spring-run Chinook
salmon runs as large as 700,000 fish between the late 1880s and the 1940s (Fisher 1994),
although these estimates may reflect an already declining population, in part from the
commercial gillnet fishery that occurred for this ESU (Good et al. 2005). Before construction of
Friant Dam, nearly 50,000 adults were counted in the San Joaquin River alone (Fry 1961).
Following the completion of Friant Dam, the native population from the San Joaquin River and
its tributaries (i.e., the Stanislaus and Mokelumne Rivers) was extirpated. Spring-run Chinook
salmon no longer exist in the American River due to the operation of Folsom Dam. Naturally
spawning populations of Central Valley spring-run Chinook salmon currently are restricted to
accessible reaches of the upper Sacramento River, Antelope Creek, Battle Creek, Beegum Creek,
Big Chico Creek, Butte Creek, Clear Creek, Deer Creek, Feather River, Mill Creek, and Yuba
River (CDFG 1998). Since 1969, the Central Valley spring-run Chinook salmon ESU
(excluding Feather River fish) has displayed broad fluctuations in abundance ranging from
25,890 in 1982 to 1,403 in 1993 (Good et al. 2005).
As noted by Good et al., (2005), the average abundance for the ESU was 12,499 for the period of
1969 to 1979, 12,981 for the period of 1980 to 1990, and 6,542 for the period of 1991 to 2001.
In 2003 and 2004, total run size for the ESU was 8,775 and 9,872 adults respectively, well above
the 1991 to 2001 average. Evaluating the ESU as a whole, however, masks significant changes
that are occurring among populations that comprise the ESU (metapopulation). For example, the
mainstem Sacramento River population has undergone a significant decline while the abundance
of many tributary populations increased. Average abundance of Sacramento River mainstem
spring-run Chinook salmon recently declined from a high of 12,107 for the period 1980 to 1990,
to a low of 609 for the period 1991 to 2001, while the average abundance of Sacramento River
tributary populations increased from a low of 1,227 to a high of 5,925 over the same periods.
Abundance time series data for Mill, Deer, Butte, and Big Chico creeks spring-run Chinook
salmon confirm that population increases seen in the 1990s have continued through 2001(Good
et al. 2005). Habitat improvements, including the removal of several small dams and increases
in summer flows in the watersheds, reduced ocean fisheries, and a favorable terrestrial and
marine climate, have likely contributed to this. All three spring-run Chinook salmon populations
in the Central Valley have long-and short-term positive population growth.
Critical Habitat
NMFS designated critical habitat for Central Valley spring-run Chinook salmon on September 2,
2005 (70 FR 52488). Specific geographic areas designated include the following CALWATER
hydrological units: Tehama, Whitmore, Redding, Eastern Tehama, Sacramento Delta, Valley-
Putah-Cache, Marysville, Yuba, Valley-American, Colusa Basin, Butte Creek and Shasta Bally
hydrological units. These areas are important for the species’ overall conservation by protecting
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