Five years of drought has not been kind to the threatened spring-run chinook salmon on Deer and Mill creeks in Tehama County.
The official count won’t be tallied for many weeks, but environmental scientist Matt Johnson estimates the number of fish on both creeks will be in the hundreds. Last year Deer Creek saw about 268 spring-run chinook return to where they were born. About 127 spring chinook returned to Mill Creek. Johnson, with the California Department of Fish and Wildlife in Red Bluff, estimates Deer Creek will see more then 300 fish this year, and Mill Creek fewer than 100.
The spring-run chinook is listed as threatened on the federal Endangered Species list. Mill, Deer and Butte creeks are grouped together as an “evolutionary significant unit,” when it comes to conservation, Johnson explained. That means they are technically the same species of fish, even though they migrate to different waterways.
Butte Creek is expected to have thousands of returning fish this year.
Johnson said the main reason there are fewer fish in Mill and Deer creeks is because more young fish die on their way to the ocean.
Where waters flow
Butte Creek dumps into the Sacramento River near Colusa at river mile 80 — 80 miles upstream from the river’s mouth. Spring-run salmon mature and get ready to spawn in pools up Butte Creek Canyon.
Mill Creek enters the Sacramento River near Los Molinos, at river mile 230, Johnson said. Deer Creek joins the river just a few miles south of Mill Creek.
“That’s literally 100 miles more of the Sacramento River that those juveniles have to swim through and survive,” he said.
Fish cycle
Spring-run chinook migrate upstream in the spring months, and spawn in September and October.
The years 2012-2015 were drought years, which means we are now seeing fish return that hatched during the drought year of 2013.
“I’m scared as a biologist, looking at what is going to happen next year and 2018,” Johnson said.
“It could be really dire for these fish.”
Along both Deer and Mill creeks, landowners have so many water rights that in times of drought the creeks could run dry if all property owners took their full water rights, Johnson said. See watershed information here: http://tinyurl.com/jfbfjnt.
Working together
In 2014 and 2015 drought years wildlife managers “worked extensively with local diverters, in some cases achieving voluntary cooperation to leave water in streams,” Johnson said.
“In other cases we had the state Water Board curtail water diversions,” to protect the threatened spring-run chinook.
Fish pulses
Los Molinos Mutual Water Co. helped work out a plan to provide more water at critical times for fish. Water manager Darrell Mullins said his company has been using pulse flows since the 1980s, which stimulates fish to migrate upstream.
Mullins said there are also plans for a new fish ladder on the upper diversion of the creek and water exchanges include wells when more water is needed for fish.
“We want to save our fish. We are proud of them,” Mullins said.
Room for hope
Salmon are resilient. In any given year some will stray to creeks where they were not born, Johnson said. Sometimes fish will migrate after two years, sometimes after four. These traits have helped fish survive through various conditions over thousands of years.
Johnson said the impacts of this most recent drought will be felt for several years.
Mill Creek has had recent improvements that should help fish over the long haul, including a new fish ladder at a lower diversion and a new fish screen.
A new fish ladder is also planned for this summer, Johnson said.
However with only a few hundred fish, the populations in these creeks are extremely vulnerable.
Just a few generations ago, before dams blocked fish from reaching the upper reaches of the Sacramento tributaries, spring-run chinook could be found in 18 tributaries.
Contact reporter Heather Hacking at 896-7758.