Biological Opinions - Bureau of Reclamation

element of coho salmon critical habitat when dissolved oxygen concentrations fall below 8 mg/L
in the mainstem Klamath River during the summer.
Restoration activities funded under the proposed action may improve water quality in the
tributaries by replacing small irrigation dams with irrigation pumps, which eliminates an
impounded area where water temperature elevates and dissolved oxygen concentrations
decrease. In addition, the creation of tailwater ponds is likely to improve water temperature,
dissolved oxygen concentrations and nutrient concentrations in tributaries by keeping warm and
nutrient rich tailwater from directly entering the tributaries.
In summary, the proposed action is likely to adversely affect water quality in the mainstem
Klamath River by slightly increasing water temperature during the spring and decreasing
dissolved oxygen concentrations during the summer. However, the proposed action is likely to
improve water quality in the tributaries by minimizing activities that elevate water temperatures,
decrease dissolved oxygen concentrations, and increase nutrients in tributaries.
11.6.4 Response and Risk to the SONCC Coho Salmon ESU Critical Habitat
Many of the physical and biological features that are essential for the conservation of SONCC
coho salmon are currently degraded. As a result of implementing the proposed action, some of
those physical and biological features will likely remain degraded, while in some cases
improvements may occur, especially in the Klamath River tributaries near IGD. The
conservation value of many of the physical and biological features in the tributaries of the
Klamath River will likely be enhanced where restoration activities occur under the proposed
action and other programs. After factoring the restoration activities under the proposed action,
the environmental baseline and the status of SONCC coho salmon ESU critical habitat, any
remaining adverse effects resulting from the proposed action to the quantity and quality of the
essential habitat types are not likely to reduce the overall conservation value of critical habitat at
the diversity stratum or ESU.
11.7 Conclusion
After considering the best available scientific and commercial information, the current condition
of coho salmon critical habitat, the environmental baseline for the action area, the effects of the
proposed action, and cumulative effects in the action area, it is NMFS’ biological opinion that
the action, as proposed, is not likely to result in the destruction or adverse modification of critical
habitat for the SONCC coho salmon ESU.
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