Placer County sees native runs of Chinook salmon - they navigate from the Sacramento river into smaller tributaries. However, the number of fish returning to our creeks is weather dependent and highly variable. Salmon need adequate depth and flow of water to travel upstream in smaller waterways. High flow years in Auburn Ravine have seen as many as 358, whereas drier years have seen as few as 11.
Chinook are essential for the health of our waterways - they begin their lives in fresh water streams, growing strong enough to venture through the delta and out to the Pacific ocean. They will spend the majority of their adult lives, anywhere from two to seven years, at sea before returning to their birth waterways where they spawn and die - bringing nutrients from the ocean upstream that support countless species.
However, our chinook populations are at risk. Historically, California was home to one of the largest salmon populations in the world - according to Dr. Carson Jeffers, over two million adult chinook salmon would return to the Central Valley before colonial contact. A mere fraction of that number of fish return to the Central Valley each year, with only 99,274 adult chinook returning to the Sacramento River Basin in 2024. Sacramento River Winter-run chinook have been listed as an endangered species since 1994 and Central Valley Spring chinook were listed in 1999.
Chinook in the central valley are adapted to California’s unique and extreme hydrology, defined by periods of flood and drought. But their life strategies have been interrupted as we have reshaped our waterways through mining, damming, and levee building.
Threats to Juvenile Salmon
Adult chinook salmon face threats coming upstream - juvenile salmon face an entirely different set of threats, primarily due to loss of side channel and wetland habitat, and irrigation canals.
Ninety-five percent of California wetland has been lost, largely due to levee building on rivers for flood control. Under normal hydrologic conditions, rivers flood and span out over wetland flood plains. These are prime habitats for juvenile salmon to feed and grow before making their journey to the ocean. Without this natural "nursery” salmon face increased predation as they travel through the delta to the ocean, due to their smaller size.
On rivers with irrigation canals, juvenile salmon face yet another danger - being sucked into unscreened irrigation drainages. Where dams slow the flow of water, juvenile salmon are naturally attracted to faster moving water being pulled into irrigation canals. In a study on Auburn Ravine, over 1700 juvenile salmon were pulled into irrigation canals, leaving them disconnected from the ocean, where they inevitably die.
Though threats to salmon are overwhelming /loom over our waterways, restoration efforts are active and promising - primarily through dam removal, wetland/side channel restoration, water management and monitoring. Reach out to Sierra Club Placer group today to join our efforts to save Placer salmon.