By closely monitoring river temperatures during a hot summer, the Nisqually Tribe has been able to make quick decisions to protect fish health.
The tribe has deployed six temperature monitors throughout the watershed. “Tribal staff regularly download data from the monitors to give tribal and state co-managers a clear picture of temperature conditions,” said David Troutt, natural resources manager for the tribe.
If a stream’s water gets too warm, juvenile salmon have to expend more energy to survive, which can often lead to starvation. Diseases that kill salmon are also more virulent and spread easily in warm water.
Low snowpack in the upper watershed coupled with a warm, dry summer has meant low flows and high temperatures in the Nisqually.
“Even as Tacoma Power lets more water through their reservoir in the upper watershed to help, we’re facing lower water and warming stream banks,” Troutt said. “These worsening conditions mean that near real-time data is important, to give us the ability to make quick decisions to protect fish.”
For example, the tribe recently closed down a weir to allow free migration of salmon through the warmer sections of the river. The tribe has been operating the weir since 2011 to separate hatchery-produced chinook salmon from naturally spawning fish migrating upriver.
“The long-term goal of creating a self-sustaining population of chinook has to take a back seat to the deteriorating conditions we’re seeing on the river,” Troutt said. “We can only hope that these changes we’re making can prevent a salmon disaster on the Nisqually this summer.”
The tribe has also worked with the city of Centralia, which has shut down hydroelectric operations on the river. The city operates a diversion dam, so shutting down power production this summer allows more water to reach a vital stretch of river for chinook.