405 



Drawdowns of Lower Snake Reservoirs and John Day Pool Offer 

 Greatest Promise to Provide In-River Passage for Migrating 

 Juveniles of Idaho's Threatened and Endangered Salmon 



by Jim Baker. Sierra Club 



Huge hj^roelectric dams — four each on the mainstems of the Lower 

 Columbia and Lower Snake Rivers — inflict the bulk of preventable 

 mortalities on the wild threatened and endangered salmon from the Snake 

 River Basin. The U.S. Army Corps of Engineers built these eight dams 

 without any provision for safe passage by migrating juvenile salmon from 

 central Idaho. This is an historical fact. 



Mainstem Dams Are the Predominant Killer of Wild Salmon from the Snake 

 River Basin 



Thus biologists at the National Marine Fisheries Service, the 

 Northwest Power Planning Council, the Columbia Basin Fish and Wildlife 

 Authority, and the Bonneville Power Administration have concluded that the 

 dams inflict at least 80-95 percent of the human-caused mortalities on wild 

 Snake River salmon. Any recovery plan for these fish must put 80 percent of 

 the effort into 80 percent of the problem. 



These eight dams inflict heavy mortalities on migrating juvenile 

 salmon in two ways: by impeding passage at the dam structures themselves, 

 and by slowing movement through the reservoirs. While the precise 

 relationship has not been established to date, more than 10,000 yeau-s of 

 successful salmon runs, more than 20 years of the best available field data, 

 and the sound professional judgment of agency and Tribal biologists all 

 confirm that, when water runs downhill faster in the Columbia-Snake Basin, 

 salmon swim upstream in greater numbers. Recent reports which find no 

 or an uncertain relationship between flows and juvenile salmon survival were 

 conducted and /or contracted by the Bonneville Power Administration (BPA), 

 electric utilities, factories directly serviced by BPA, or Snake River seaports 

 — all of which oppose substantially greater flow augmentation and the 

 reservoir drawdowns. (For further discussion, see Appendix A.) 



Only three means — fish transportation, flow augmentation, and 

 reservoir drawdowns — have been realistically proposed to pass migrating 

 juvenile salmon past the dams and through the reservoirs. 



Juvenile Fish Transportation Is a Failed E^xperiment 



While the Corps of Engineers has conducted its fish transportation 

 experiment for more than 15 years. Snake River salmon populations have 

 dropped to the brink of extinctions. The Corps has never demonstrated any 



Drawdowns Oflfer Greatest Promise — Pcige 1 



