Friday June 24, 2022

The Lewiston Tribune

As the planet warms, Idaho’s high-elevation streams may remain cold enough for spring chinook salmon, but lower flows will reduce the abundance and quality of spawning and rearing habitat, according to a soon-to-be-published study.

Snowpack-dependent flows have already dropped about 20% from levels recorded in the late 1950s. That decreased spawning habitat by about 10%. Flow velocity is down 17% and side channel habitat declined 6%.

But those losses are modest compared to what researchers led by University of Idaho professor Daniele Tonina predict will happen in the future.

“Before, the headwater streams were an ideal place,” Tonina said. “Now they will be less ideal.”

Tonina’s team used a new type of lidar, a remote sensing system, combined with hydraulic modeling, to predict how Bear Valley Creek, a tributary to the Middle Fork of the Salmon River, will change as air temperatures become warmer and more winter precipitation falls as rain instead of snow, and mountain snowpacks don’t persist as long into summer months.

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