EPA's Vessel General Permit and Small Vessel General

quality growth, reproduction, and feeding. The critical habitat designation for this ESU
identifies primary constituent elements that include sites necessary to support one or more
Chinook salmon life stages. Specific sites include freshwater spawning sites, freshwater rearing
sites, freshwater migration corridors, nearshore marine habitat and estuarine areas. The physical
or biological features that characterize these sites include water quality and quantity, natural
cover, forage, adequate passage conditions, and floodplain connectivity. The critical habitat
designation (70 FR 52488) contains additional details on the sub-areas that are included as part
of this designation, and the areas that were excluded from designation.
In total, Central Valley spring-run Chinook salmon occupy 37 watersheds (freshwater and
estuarine). The total area of habitat designated as critical includes about 1,100 miles of stream
habitat and about 250 square miles of estuarine habitat in the San Francisco-San Pablo-Suisun
Bay complex. This designation includes the stream channels within the designated stream
reaches, and includes a lateral extent as defined by the ordinary high water line. In areas where
the ordinary high-water line is not defined the lateral extent is defined as the bankfull elevation.
In estuarine areas the lateral extent is defined by the extreme high water because extreme high
tide areas encompass those areas typically inundated by water and regularly occupied by juvenile
salmon during the spring and summer, when they are migrating in the nearshore zone and relying
on cover and refuge qualities provided by these habitats, and while they are foraging. Of the 37
watersheds reviewed in NMFS' assessment of critical habitat for Central Valley spring-run
Chinook salmon, seven watersheds received a low rating of conservation value, three received a
medium rating, and 27 received a high rating of conservation value for the species.
Factors contributing to the downward trends in this ESU include: reduced access to
spawning/rearing habitat behind impassable dams, climatic variation, water management
activities, hybridization with fall-run Chinook salmon, predation, and harvest (CDFG 1998).
Several actions have been taken to improve and increase the primary constituent elements of
critical habitat for spring-run Chinook salmon. These include improved management of Central
Valley water, implementing new and improved screen and ladder designs at major water
diversions along the mainstem Sacramento River and tributaries, removal of several small dams
on important spring-run Chinook salmon spawning streams, and changes in ocean and inland
fishing regulations to minimize harvest. Although protective measures and critical habitat
restoration likely have contributed to recent increases in spring-run Chinook salmon abundance,
the ESU is still below levels observed from the 1960s through 1990. Many threats still exist.
Final Protective Regulations
On June 28, 2005, as part of the final listing determinations for 16 ESUs of West Coast salmon,
NMFS amended and streamlined the 4(d) protective regulations for threatened salmon and
steelhead (70 FR 37160) as described in the Protective Regulations for Threatened Salmonid
Species section of this document. Under this change, the section 4(d) protections apply to
natural and hatchery fish with an intact adipose fin, but not to listed hatchery fish that have had
their adipose fin removed prior to release into the wild. The amended June 2005 4(d) rule
applies to the Central Valley spring-run Chinook salmon ESU.
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