Fish Guidance Systems

Water temperatures crucial for Chinook salmon

With California potentially facing a continuation of drought conditions into a fourth year, officials are making plans to hold back more water at Shasta Lake next year in an effort to save an increasingly endangered species of fish – the winter-run Chinook salmon.

This would help to keep water temperatures in the Sacramento River at 56 degrees F (13.3 degrees C) or lower, the threshold for keeping juvenile salmon alive. It is estimated that around 95% of juvenile winter-run Chinook salmon died in 2014 as a result of temperatures becoming too warm. A previous attempt to maintain low water temperatures appear to have failed, partly because it was found that temperature gauges were faulty and the river was running warmer than predicted. By the time officials made further restrictions to the release of water from Shasta Lake, temperatures were occasionally creeping as high as 58 degrees F (14.4 degrees C), and in October 2015 officials with the National Marine Fisheries Service said preliminary data showed even more of the juvenile salmon were killed this year.

The measuring of water temperature in 2016 will be crucial. Chinook salmon has a three-year spawning cycle and could face extinction if they suffer a third year of high mortality rates, according to a water board staff report. The winter-run Chinook are listed as endangered under the federal Endangered Species Act.

Garwin Yip, Branch Chief of Water Operations, with NOAA Fisheries Central Valley Office says limited water resources require hard choices. "As far as water goes, if we're in another drought year it's going to be tough for everybody including the fish."