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The Anti-Salmon Crowd by Borg Hendrickson Idaho Press, May 7, 2019

To confuse you, dam proponents, including some in Congress, tout Columbia Basin’s Snake River per-dam juvenile salmon survival rate as if it applied cumulatively to the entire waterway.

The Corps of Engineers cites a per-dam survival rate trending toward 95 percent, which may be true ... but is deceptively used. Here’s why: The anti-salmon crowd fails to tell you that accumulated dam-by-dam losses through all eight dams leaves only 66 percent survival and doesn’t account for losses occurring in the dams’ reservoirs.

The National Oceanic and Atmospheric Administration’s report does. In 2018, NOAA reported a Snake River juvenile spring-summer chinook survival rate -- from the head of slack water (near Lewiston) to Bonneville Dam’s tailrace (the lowest tailrace) -- at just 38 percent. NOAA also reported a long-term average of just 49 percent.

However, none of the above rates include "delayed mortality." These losses occur between Bonneville and the ocean and result from stress and harms juveniles suffer as they pass through the eight-dam and reservoir obstacle course. Researchers estimate delayed mortality losses of 36 percent to 76 percent.

Therefore, including, as we must, delayed mortality, in 2018 the total Snake River juvenile salmon survival rate ranged between 24 percent to 9 percent. These figures tell the sad, whole-truth story.

Related Pages:
Snake River Dams -- Setting the Record Straight by Kristin Meira, Capital Press, 5/6/19