Water quality issue from Yolo refuge overflow has killed 76 salmon - FISHBIO

Monday November 15, 2021

Daily Republic —

Seventy-six Chinook salmon died when the oxygen content at the lower end of Putah Creek reached extremely low levels due to a high organic material buildup in the water.

It is possible, however, that as many as two dozen of the fish perished because beavers had stopped the flow of water before their dams could be breached, said Rich Marovich, the retiring streamkeeper for the Lower Putah Creek Coordinating Committee and the Solano County Water Agency.

Only four salmon are known to have traveled upstream to spawning areas since the boards at the Los Rios Check Dam were removed Nov. 2.

“It’s an unfolding story. It’s early in the migration season so if we get some more rain events, we attract more fish,” Marovich said. “So it’s not necessarily a dire result at this point, but it is a concern.”

Marovich said the heavy rains Oct. 24 dislodged loads of organic material and caused an overflow from the east levee to drain into the Yolo Bypass Wildlife Area.