Condit Dam Removal Condit Dam Removal - Access Washington

Condit Dam Hydroelectric Project
Final Supplemental EIS
Potential Impact of Anadromous Salmonids on Resident Rainbow Trout
The establishment of anadromous rainbow trout (steelhead) above Condit Dam is unlikely to
have a measurable impact on the population of river-resident rainbow trout in the mainstem
of the White Salmon River where conditions are most favorable for resident rainbow trout
(Cramer et al. 2003 and 2005, Nielsen 2005). It is, however, possible that a portion of the
production of small stream resident rainbow trout and juvenile rainbow trout in the
Rattlesnake Creek subbasin may convert to juvenile steelhead trout. This would be due to
the low flows and high temperatures of the Rattlesnake Creek watershed favoring the
production of steelhead juveniles over resident rainbow trout. Cooler tributaries entering
from the west (Buck and Mill Creeks) are likely to have habitat more favorable to resident
rainbow trout (Cramer et al. 2003 and 2005). Production of steelhead smolts upstream of
Husum Falls is likely to be low due to the mainstem habitat being favorable to the production
of resident rainbow trout and difficult upstream passage for juvenile steelhead trout produced
in tributary streams below the falls. Additional information about the interactions of resident
and anadromous rainbow trout ecotypes can be found in Section 5 of Appendix C.
If hatchery supplementation is used to reintroduce a reproducing population of steelhead
trout, impacts to resident rainbow trout populations can be minimized by methodologies
listed in Section 5 of Appendix C.
Beneficial Effects of Dam Removal on Fish
Potentially, 32.4 miles of new steelhead habitat and 15.3 miles of new salmon habitat may be
accessed by anadromous salmonids after dam removal, increasing the run size and long-term
viability of anadromous salmonid populations in the White Salmon River and increasing the
availability of salmon and steelhead angling opportunities in the White Salmon River basin.
The benefits of restoring access to anadromous and migratory salmonid habitat in the White
Salmon River through the removal of Condit Dam are discussed in the Washington
Conservation Commission WRIA 29 limiting factors report (WCC 1999) and the White
Salmon River subbasin summary prepared for the Northwest Power Planning Council by
WDFW (2000) and are part of the larger recovery effort for ESA-listed salmonids in the
lower Columbia River. New thermal refuge habitat for migrating Columbia River
anadromous salmonids from other sub-basins also would be accessible after the removal of
Condit Dam. Additional stream habitat for resident fish would be created in the lakebed of
the former reservoir. Additionally, the small increase in water temperature below Condit
Dam from the discharge of warmed reservoir surface water would be eliminated, improving
the quality of thermal refuge, and the recruitment of gravel and large woody debris from
sources above the dam site would be reestablished. Foraging, wintering, and refuge habitat,
and possibly spawning habitat, would be created for Columbia River bull trout. Juvenile
anadromous salmonids would provide forage for bull trout, and salmon carcasses in the
watershed above the site of Condit Dam would provide an additional source of marinederived
nutrients to the watershed. There would be more suitable substrate for streamdwelling
aquatic macroinvertebrates after the stream substrate has stabilized.
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