The WA Department of Ecology’s Final Supplemental Environmental Impact Statement concluded that significant unavoidable adverse impacts would occur with breeching of Condit Dam, however, the following recovery is expected as the system is restored:
- Turbidity spikes are predicted to near background levels within 3 to 5 years.
- Macroinvertebrates will likely take several years to fully reestablish.
- Chum salmon (imprinted to return) run size during the years that the lost year-class would be expected to return as mature spawners will be reduced and composed entirely of spawners from other year classes and will potentially take several generation cycles to return. In addition, it is likely that the spawning substrate necessary for their reproduction will be impaired by fine sediment during the second year (and not fully recovered for 1 to 3 years after that). New gravel recruited from upstream may not reach the lower 2.6 miles during that time. The result will be essentially a loss of several year-classes of chum salmon. The long-term increase in available chum salmon spawning habitat is expected to increase chances of successful recolonization of the White Salmon River basin by chum salmon.
- With exception of mussels, benthic macroinvertebrates (such as crustaceans and aquatic insects) recolonization should occur within 6 months to a year. Mussels have longer life-spans and are relatively slow growing and will take more time to recolonize new substrates.
- The loss of approximately 2.8 acres of lake fringe wetlands is expected to be mitigated by establishment of riverine and slope wetlands within 1 to 5 years of dam removal.
Here are the PacifiCorp habitat restoration plans.
The salmonid recovery strategy, which also includes Endangered Species Act listing status, for the White Salmon River can be found here. Here are a couple recent paper abstracts on the topic. An anadromous fish passage inventory for the White Salmon River and its tributaries can be found here. Based on the inventory, Underwood Conservation District’s top 10 project list is:
1. Buck Creek: White Salmon Irrigation District dam and diversion fish passage and screening improvements
2. Indian Creek: fish passage restoration through culvert at RM 0.05
3. Mill Creek: fish passage restoration through culvert at RM 0.32
4. Indian Creek: fish passage restoration through culvert at RM 1.30
5. Rattlesnake Creek: habitat enhancement including mitigation of cattle impacts, riparian planting, large woody debris placement and invasive species removal
6. Buck Creek: habitat enhancement including instream, side channel and riparian habitats
7. White Salmon River: habitat enhancement of floodplain
8. White Salmon Tributary 9.90 and 9.91: fish passage restoration and riparian enhancement
9. Indian Creek: riparian enhancement and thinning in Reach 1
10. Upper Rattlesnake Creek: enhancement of hydrologic conditions
A US Fisheries and Wildlife progress report on White Salmon River bull trout can be found here.