Marking the second time in the past six years, nearly the entire hatch of endangered winter-run chinook salmon were wiped out in 2021 due in part to high water temperatures in the Sacramento River in the Redding area.
Fisheries officials said a vitamin deficiency in adult fish also likely contributed to the deaths of their offspring.
Only about 2.6% of the wild winter-run salmon that hatched in the river survived long enough to make it to Red Bluff, according to a memo from the California Department of Fish and Wildlife.
And then less than half of the fish that made it to Red Bluff also survived to make it out to the San Joaquin Delta. It was one of the worst years on record for winter-run survival, according to the National Marine Fisheries Service.
"Clearly, it was a grim year for winter-run chinook. The temperatures were not favorable in the river, which obviously was a result of the low water (in Lake Shasta) and the high temperatures" in the Sacramento River, said Michael Milstein, a spokesman for the National Marine Fisheries Service.
Even before the past two years of drought, the winter-run were having a rough go of it. The winter-run are an endangered species, and nearly all the fish spawn in the in the river and tributaries in the Redding area.
Open the Golden Gate: Young salmon hitch ride to the Pacific
But warm river temperatures and the drought were only partly to blame for the fish die-off, Milstein said.
A diet-based thiamine deficiency among female adult fish in the ocean was passed on to the young fish and also contributed to their deaths, he said.
Debate over Shasta Dam water releases
John McManus, president of the Golden State Salmon Association, said federal and state agencies were to blame for letting too much water out of Shasta Dam and leaving warm water in the river that killed the young fish.
The U.S. Bureau of Reclamation, which operates Shasta Dam, received permission from the State Water Board to continue to supply water to farmers south of Redding, McManus said.
"And the change we'd like to see is before the state board grants permission to violate the rules, they first require the big water operators to reduce deliveries of water to the agricultural sector so that everybody is sharing in the pain and it doesn't just all fall on the salmon fishery," McManus said.
During last year's drought, those with junior water rights, such as the Bella Vista Water District in Redding and Clear Creek Community Service's District in Happy Valley, had their allocations from the bureau severely reduced.
Those agencies with senior water rights, such as the Anderson-Cottonwood Irrigation District and some irrigation agencies south of Red Bluff, had their allocations cut 25%.
The city of Redding, which has both junior and senior water rights, had water cuts ranging from 25% to 75%.
"So I've got no beef with delivering water to Redding. You've got a bunch of people there that need water. But downstream, it's a long way down to the Delta. And there's quite a bit of water that was released out of Lake Shasta last year that never made it as far as the Delta. And it didn't go to urban areas. It didn't go to human health and safety and it sure as heck didn't go to keep the salmon fishery afloat," McManus said.
But Don Bader, Redding area manager for the bureau, disputed McManus' claims about violating state and federal water-use rules.
He said irrigation agencies south of Redding did have their water allocations cut back.
In 2021, the bureau faced very low levels in Lake Shasta and little rain for the second year in a row, Bader said.
"So we started out in a very, very tough situation going into the spring and summer, and then based on that, in May, we developed the best available temperature management plan in coordination with both state and federal agencies. Given these dire conditions, and I want to emphasize, we did not run out of cold water (in Lake Shasta) based on this plan that was developed in May," Bader said.
Cold water needed to protect fish
Cold water is necessary for winter-run salmon eggs to hatch and the newborns, called fry, to survive.
Before Keswick and Shasta dams were built, the winter run used to spawn in the rivers and creeks upstream of where Lake Shasta is now.
Fisheries biologists say the winter-run need the type of cold water they used to spawn in before the dams were built. So operators at Shasta Dam try to release cold water from lower levels in the lake to ensure the salmon eggs and young hatches survive.
The young fish start to die when the water temperature in the river exceeds about 57 degrees.
In a letter to National Marine Fisheries Service and state Department of Fish and Wildlife officials, Erica M. Meyers chairperson, Winter-Run Project Work Team for the state, said the water temperatures in the river at times were too warm.
"Winter-run Chinook Salmon in 2021 spawned during one of the warmest and driest years on record, and Sacramento River water temperatures during the majority of the incubation period exceeded limits for safe egg incubation," Meyers wrote.
Most of the salmon caught in the ocean and in fresh water streams are raised in hatcheries, including Coleman National Fish Hatchery in Anderson.
But McManus said when the winter-run suffers, it affects the entire fishery and there can be restrictions on the number of salmon that can be caught.
Still "tough sledding ahead"
There are four species of salmon that spawn in the Sacramento River and its tributaries: the winter run, fall run, late fall and spring run.
Milstein said that in light of the past two years of drought, fisheries officials with his agency predicted about 25% of the young fish would make it to Red Bluff.
In 2014 and 2015, more than 90% of salmon hatches died in the river before reaching Red Bluff. That die-off was due to warm water in the Sacramento River, officials said.
The Livingston Stone Fish Hatchery near Shasta Dam does raise winter-run chinook salmon to help ensure the species survival.
In the long run, state and federal officials are trying to get winter run to spawn in other North State streams, so the fish aren't completely dependent on the Sacramento River in the Redding area, Milstein said.
There are plans underway to truck winter-run salmon around Shasta and Keswick dams and reintroduce them to the McCloud River for spawning there, he said.
The bureau is also working on removing barriers on Battle Creek that would allow fish to spawn upstream of Coleman fish hatchery.
Bader said that despite the recent rains in December, Lake Shasta was still very low for this time of year and the state could face more drought conditions in 2022.
"We're still at the lowest level on Jan. 4 for Lake Shasta on record, so we still have some really, really tough sledding ahead of us if we don't get more rain," he said.
Damon Arthur is part of a team of journalists who investigate wrongdoing and find the unheard voices to tell the stories of the North State. He welcomes story tips at 530-338-8834 by email at firstname.lastname@example.org and on Twitter at @damonarthur_RS. Help local journalism thrive by subscribing today!
This article originally appeared on Redding Record Searchlight: Warm water leads to thousands of salmon deaths in the Sacramento River