By Rocky Barker
rbarker@idahostatesman.com
October 07, 2017
 
STANLEY, ID. What is the future of the Columbia River and its salmon? Look to 2015.

That year’s extraordinary combination of overheated river water and low flows killed hundreds of thousands of returning sockeye salmon, devastating a run that had rebounded from near-extinction.

Millions of new sockeye and steelhead smolts migrating the opposite way, to the Pacific, died throughout the river system; only 157 endangered sockeye made it back to the Sawtooth Valley this year.

By the middle of this century, scientists suggest, the temperatures we saw in 2015 will be the norm. The low snowpack and streamflows were examples of what the Pacific Northwest should expect at the end of this century due to rapid climate change caused by the burning of fossil fuels, climatologists say.

“2015 will look like an average year in the (2070s) and there will be extremely warmer years than that,” said Nate Mantua, a NOAA atmospheric scientist in Santa Cruz, Calif.

Scientists, politicians and energy officials have argued for decades over the best way to restore troubled salmon runs along the Columbia and Snake. Their focus has largely been on the dams and human development that reshaped the rivers. But regardless of what other steps we take for the fish, climate change could catch up with them in the coming decades and pose a major threat.

Already, scientists have seen regional snowmelt reach rivers an average of two weeks earlier than historical records indicate. The average temperature of the Columbia River and its tributaries has risen more than 1 degree Fahrenheit since 1960.
     
Climate modelers at the University of Washington’s Climate Impacts Group predict  <https://cig.uw.edu/resources/special-reports/> that the Pacific Northwest’s average annual temperatures will rise a total of 4 to 6 degrees Fahrenheit by 2050. High estimates suggest the increase could exceed 8 degrees, said Joe Casola, the group’s deputy director.

Salmon and steelhead that migrate in the summer and those that spawn and rear in lower-elevation tributaries to the Columbia may not survive these temperatures. In water of just 68 degrees, salmon will begin to die.

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