Development has made the Pilchuck River warmer, harming fish
GRANITE FALLS — The Pilchuck River is getting warmer, and that’s not a good sign for future salmon runs.
The temperature of the water has risen about 5.4 degrees Fahrenheit above the historic norm, according to the state Department of Ecology.
Higher temperatures stress fish — including endangered species of salmon — and make them more susceptible to disease while affecting their reproductive system. The Department of Ecology released a plan this month detailing strategies to cool down the river.
Development is the main cause of warmer water into the river, Ecology watershed planner Heather Khan said.
A thick canopy of forest once shaded the Pilchuck River, she said.
Logging practices, agricultural uses and the conversion of land into hard, impervious surfaces like concrete all play a role in raising temperatures, she said. Climate change might play a role, but Ecology hasn’t studied that as a potential contributing factor.
Higher temperatures in the river slow down a fish’s swimming speed, making it more susceptible to predators, Khan said.
https://www.heraldnet.com/news/development-has-made-the-pilchuck-river-warmer-harming-fish/