Biological Opinions - Bureau of Reclamation

12.4 Effects to Individuals
The proposed action affects SONCC coho salmon through the Project Operations and the annual
restoration funding of approximately $500,000. Project Operations affect coho salmon through
hydrologic and habitat modifications in the mainstem Klamath River, while the annual
restoration funding affects coho salmon during restoration implementation and through habitat
improvements. Note that the use of the term “proposed action” in the Project Operations section
represents Klamath Project operations component of the proposed action, while the use of the
term “proposed action” in the Restoration Activities section represents the habitat restoration
component of the proposed action.
12.4.1 Project Operations
As stated in the Effects to SONCC Coho Salmon ESU Critical Habitat section, the coho salmon
effects analysis is based on the results of the formulaic approach described in the proposed action
and on one element of the proposed adaptive management where details are sufficient for
analysis. Besides the proposed near real-time management for minimizing disease risks, the
coho salmon effects analysis does not include the proposed adaptive management because
NMFS does not have sufficient information on the adaptive management approach at this time.
Under the proposed action, the median Project delivery from all sources by water year is 428,200
acre-ft with a minimum of 178,000 acre-ft and a maximum of 477,000 acre-ft (Reclamation
2012). Approximately 80 percent of the Project water delivery is not returned to the mainstem
Klamath River (Cameron 2013). Therefore, approximately 20 percent of the Project water is
returned to the Klamath River as agricultural tailwater, which contributes to impaired water
quality in the Klamath River. The proposed action’s effects to coho salmon result from the
reduction to flows at IGD.
12.4.1.1 Exposure
As previously discussed in the Hydrologic Effects section (i.e., section 11.4.1.1), the proposed
action reduces flows in the mainstem Klamath River throughout most of the year. Therefore, all
life stages of coho salmon are expected to be exposed to proposed action effects in the next ten
years (Table 12.5). However, different populations of coho salmon will be exposed to varying
levels of flow effects under the proposed action. Populations proximal to IGD will experience
the most pronounced exposure, while populations farthest away, such as the Lower Klamath
River population, are not likely to be exposed.
Adult coho salmon are present in the mainstem Klamath River only during the upstream
migration and spawning period. Upstream migration of adult coho salmon in the Klamath River
spans the period from September to January, with peak movement occurring between late-
October and mid-November. In most years, all adults are observed in tributaries prior to
December 15, while in some years (e.g., Scott River in 2009) most adults are observed between
December 15 and January 1. Therefore, adults that spawn in tributaries are expected to be
exposed primarily in the late fall to early winter.
336