Copyright Santa Rosa Press Democrat
For California water managers, the Sierra snowpack has always been like money in the bank. With steady kisses of spring sun, snowmelt reliably flows ever downward until reaching the state’s vast network of reservoirs downstream. But in the spring of 2021, in what turned out to be the second year of a scorching three-year drought, something happened to a meager snowpack. Much of it unexpectedly vanished into the sky or ground. Summer, as it now tends to do, had arrived early. Faced with a cruel choice of who gets the limited water and who goes without, human decisions designated the remnants of California’s once-massive salmon population as the losers. The operators of the state’s largest reservoir, behind Shasta Dam, had already begun to honor contracts that guarantee farmers a lot of water, come drought or deluge. That meant less water in the Sacramento River to keep its inhabitants alive. When adult salmon returned from the Pacific Ocean that winter, they swam upstream to below the dam where they would traditionally spawn. But the low flow in the river was lethally hot. Nearly all the salmon eggs failed to produce offspring. The tragic loss of these salmon is one of too many examples of how California keeps harming an iconic fish species it is supposed to protect. A drought is a setback for salmon in the best of times. Here is how the last one could not have been worse, thanks to human mistakes. California droughts do not announce their arrival or a scheduled departure. The rains simply stop arriving as frequently and California begins to dry up, like it did between October 2020 and September 2021. The period had the lowest rainfall statewide in nearly a century. When the U.S. Bureau of Reclamation completed construction of 602-foot-high Shasta Dam in 1940, it also did something as durable. It contractually promised to longtime water users downstream that their droughts were over. Even in the driest of years, Shasta would provide no less than a 75% allocation of water. For these water districts, that amounts to 1.5 million acre-feet of water, some 487 billion gallons. Both the state and federal governments honored similar contractual promises just about wherever they built Northern California dams. In 2021, the Sierra started February with a below-average snowpack (70% of average). By the beginning of May, that had plummeted to 6% of average. Meanwhile, one of the largest salmon populations in years, some 10,000 winter-run salmon, had been migrating from the ocean to the Sacramento River below Shasta to spawn. But water operators had overestimated Sierra supplies making it into reservoirs by more than 1.3 million acre-feet, the equivalent of two years’ supply for the city of Los Angeles. And the federal government stuck to its contractual water promises to farmers, leading Shasta to plummet to its lowest level in 44 years. An estimated 75% of the salmon eggs died in the Sacramento River that summer because the river, a trickle compared to a wet year, was too hot. Only 3% of all the eggs ultimately survived. California came dangerously close to losing that year’s entire endangered population of the fish. It was because salmon don’t have the same contract for guaranteed water as some “senior” human water users, even though salmon, Californians for tens of thousands of years, are among the most senior residents of them all. Despite the 2021 salmon tragedy on the Sacramento River, there was still hope. One- and 2-year-old California salmon were still in the Pacific awaiting their migration when full adults. But three-quarters never got the chance to spawn. We accidentally ate too many of them. Fishing regulators adjust up or down California’s salmon “harvest” based on how many salmon are believed to be in the ocean, so that sufficient salmon survive to migrate home and spawn. In 2022, the goal was a harvest of about half of an estimated population of 400,000 salmon. But the estimate proved wrong. A follow-up review concluded that the salmon population had been closer to 250,000. So instead of recreational and commercial fishermen catching 50% of what was thought to be in the Pacific, they caught 75% of what actually was there. The result was that the number of fish that survived to migrate and spawn was only half the target. Fishermen are without question among the fiercest human advocates for this species. But we have reached the point where no flaw in salmon management can get a pass. Our best science has overestimated salmon’s ocean populations more often than not over the past two decades. That has led to higher fishing levels. The accidentally high fishing levels of 2022 contributed to a missed opportunity to rebuild salmon populations with more adults returning to spawn. New Year’s Day 2023 was the wet aftermath of a massive atmospheric river that had slammed Northern California. By April, the Sierra snowpack was 231% of the historic average. The drought had broken (although it would take the governor another 17 months to formally declare so). Finally, there was water for salmon. All the dams refilled to a combined 123% of average. Nature couldn’t have designed more perfect conditions for the adult salmon still in the Pacific to return. The rarest California salmon of them all is the one that returns from the ocean in the spring. Its favorite habitat is a single creek, a tributary of the Sacramento River, the confluence near Colusa. Human monitoring efforts estimated that more than 20,000 spring run salmon returned during the hot drought of 2021, more than 90% dying in the warm creek before spawning. In 2023, less than 100 salmon returned to Butte Creek. And then PG&E killed more than half of them. It was, again, an accident. Above the creek is a canal with diverted water to generate hydropower. In August 2023, the canal burst, sending a mountainside of mud into Butte Creek. The life-choking sediment turned the creek orange. It killed nearly 60% of those few salmon and was equally lethal to endangered Central Valley steelhead and yellow-legged frogs. The Federal Energy Regulatory Commission would ultimately find PG&E at fault and order a plan to mitigate the harm. But how do you repair a year’s run of salmon that was down to less than 100 survivors? In one positive sign, this year’s preliminary return appears to be in the low thousands. That is lower than some historical numbers, but far better than nearly undetectable. These examples of human mistakes are by no means equal. How we have over-committed this system to providing large water supplies in the driest of years, as happened in 2020, is a much more lethal and unresolved long-term threat to salmon than one mishap on a creek or a miscalculation of ocean fishing levels by an agency doing its scientific best to sustain the population. Missing here is the most deadly spot in the life cycle for salmon, which is downstream from the reservoirs. We have simply reached the point where there is precious little room left for more human error. And if California hasn’t learned from its recent past, it could only take a few more rounds of mismanagement for wild salmon, seemingly an indestructible species, to begin disappearing from our rivers. Tom Philp is a columnist for the Sacramento Bee.
