Biological Opinions - Bureau of Reclamation

viability for coho salmon and other salmonids during the ESA section 11(a)(1)(B) permit
duration (NMFS 2012b).
PacifiCorp will actively participate in a flow variability team that will develop fall and winter
and spring flows. Fall and winter flows will be designed to redistribute spawned-out adult
salmonid carcasses which likely are concentrated in the upper basin causing the potential for
disease outbreaks to occur, and will also be designed to scour channel bottom fine sediment and
organic matter. These actions will help reduce the prevalence of P. minibicornis and C. shasta,
the organisms tied to health related impacts on coho. Increased spring flows are expected to aid
in maintaining or expanding summer rearing habitat for juveniles occupying the Upper Klamath
reach. Based on analyses presented in NMFS (2010a), NMFS concludes that the availability of
rearing habitat will increase with PacifiCorp’s cooperation in implementing RPA flows and
increase juvenile survival though the smolt stage. Spring flow objectives will also include
timing release of flows to reduce smolt transit time through disease prone areas. The relationship
between increasing discharge and faster smolt migration has been identified for salmonid species
in other regulated rivers (Berggren and Filardo 1993, Giorgi et al. 1997). Increased migration
speed likely also reduces exposure time to predators, thereby improving smolt survival (NMFS
2012b).
The augmentation of gravel in the river downstream from IGD will partially restore conditions
for coho salmon spawning in the river during fall. Properly functioning spawning substrate
provides ample interstitial flow through redds, and is of suitable size to permit efficient redd
excavation by spawning adults. Effective salmon spawning has been observed downstream of
other dams, where suitable substrate has been present (Giorgi 1992, Geist and Dauble 1998).
NMFS expects the same potential to be realized below IGD. The Project-related effects on
gravel, and the concomitant benefits of gravel augmentation, are expected to be largely restricted
to the uppermost several miles of the Upper Klamath reach below IGD. As such, gravel
augmentation is not expected to substantively alter conditions further downstream in the Middle
Klamath and Lower Klamath reaches. In the Sacramento-San Joaquin River system, gravel
augmentation is a common practice, and researchers there have observed increased spawner use
of the new gravel supplied by gravel augmentation (Merz and Chan 2005, Cummins et al. 2008).
Overall, NMFS expects that implementation of the gravel augmentation measures will improve
the functionality and conservation value of critical habitat for adult spawning below IGD as
compared to current conditions (NMFS 2012b).
The quarterly augmentation of LWD recruitment to the Upper Klamath reach will add to the
habitat complexity below IGD, resulting in improvements to the conservation value of critical
habitat for rearing juveniles. The transport of trapped LWD on a quarterly basis either to the
Klamath mainstem directly or for use in constructed habitat features, will improve habitat
complexity or, in some cases, provide localized thermal refugia in the form of shade. Both of
these habitat features enhance survival of juvenile coho by affording protection from predators
and cooling water during critical periods in the late summer and fall. NMFS believes the
quarterly transport of the expected small amount of LWD trapped by PacifiCorp reservoirs to
areas downstream of IGD, or to be reserved for the construction of habitat enhancement projects
(e.g., complex wood jam structures), will not result in adverse effects to juvenile and smolt
migration corridors as the interruption is a relatively short duration. Once placed downstream of
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