Each winter, rains pulse through Oregon’s forests. If we’re lucky, much of this precipitation falls as snow at high elevations, blanketing the Cascades in winter white. As the season turns toward spring, warmer temperatures signal early snowmelt, and the Willamette River basin surges.
As rain and snowmelt gather and spill across the valley floor, they also send a signal that the time has come for spring Chinook salmon to return home. Around late February, the waters have called dozens of these migratory fish back from the Pacific Ocean. Weaving their way through the Columbia River estuary, they take a sharp turn southward, pushing into the Willamette.
They’ve come earlier than their peers who return each fall. Driven by ancient knowledge of the streams their ancestors have called home since time immemorial, they’ve arrived when the flows are just right for climbing and crossing Willamette Falls just outside of Portland. And they keep coming.
Over the span of a month, this cohort of migrating spring Chinook salmon will pass over this natural spillway and travel upstream, carrying with them eggs, milt, and an abundance of marine-derived nutrients gathered during their time in the Pacific.
These fish will spend their summers in the Willamette, congregating in deep pools and cold-water refuges. Back in freshwater, they will not eat again, instead relying on the fat and nutrients carried home with them. As summer arrives, they’ll move farther upstream, chasing cold water.
As the first rains return each September, it’s time for the final leg of the journey. These incredible fish press into the upper reaches of the watershed to spawn in an ancient ritual of return.
Born in the McKenzie River
Upper Willamette River spring Chinook are a distinct group of Chinook salmon adapted to the rivers above Willamette Falls, and our namesake McKenzie River supports one of the most important remaining populations of native spring Chinook in the Upper Willamette Basin. Today, these fish are protected as threatened under the Endangered Species Act.
A salmon’s life begins and ends in a river’s gravel. As September arrives on the McKenzie, a female salmon seeks calmer waters where a range of rock sizes have been deposited across the riverbed. She’ll use her tail to excavate and gather gravel into a protective nest for her young, digging and sorting through day and night. This nest is called a redd. It protects her fertilized eggs and later serves as a home for emerging young fish called alevins. These tiny fish live off a yolk sac while tucked among the gravel for weeks or months, protected by their mother’s skillfully constructed nest.
As the weeks pass, tiny salmon called fry emerge from the gravel and begin one of the most vulnerable chapters of their lives. These fish may be small, but they require a surprisingly complex river system to thrive.
Young salmon need more than flowing water. They require the habitat complexity offered by side channels, shallow edges, large wood that pools water behind it, backwaters, and alcoves. These are the places where fast winter water slows down, leaves and twigs collect, and insects gather. Connected floodplains provide young salmon with places to hide, feed, rest, and grow before beginning their journey toward the ocean.
Research in the McKenzie and throughout the Willamette Basin continues to show just how important this variety of habitat can be for juvenile Chinook as they prepare for several years at sea.
A River With Room to Roam
Historically, the McKenzie River cascaded out of the Three Sisters Wilderness, moving swiftly as steep slopes shaped a path downward. Flowing into the area near Rainbow, the river changed dramatically as ancient glacial scars slowed elevation change and spread the water across a wide and complex floodplain. Here, the river split and braided around islands and fallen trees before coming together again near Vida.
As western expansion reached the area in the late 1800s, dams, roads, development, gravel mining, forestry practices, and other changes led to a simplified river system. Dredging to support material transport carved out a new river channel, offloading sediment into side channels and alcoves. As people worked to create a more predictable river system, channels disappeared, large wood became scarce, and in many places, the ancient web of waterways was transformed into a single, fast-moving channel.
Though this new river system aided the construction of communities and industry along the McKenzie River and other waterways across the Pacific Northwest, these changes also came at the cost of something critical: safe places for salmon to grow.
A fast channel can be a difficult place for small fish to survive a winter storm. A connected floodplain offers alternatives: slower water, cover from predators, and productive feeding areas rich with insects and organic matter. That is one reason McKenzie River Trust and our partners have invested so heavily in reconnecting floodplains at places like Finn Rock Reach, Quartz Creek, and the Lower South Fork McKenzie River.
At Finn Rock Reach, the change is already visible. After restoration reconnected the river with its floodplain, spring Chinook salmon quickly returned to spawn across the site. In the fall of 2023, following the completion of restoration here, NOAA documented 65 redds in the project area. Each of these nests held a new generation of young salmon growing among the gravels that gathered in the restored channels.
Carrying the Ocean Home
Each of these channels eventually flows downstream. After months of foraging and growing, young Chinook travel downstream, leaving the McKenzie for the Willamette, Columbia, and finally the Pacific Ocean. Along the way, they undergo an extraordinary transformation called smoltification, preparing their bodies for life in saltwater. In the Columbia River estuary, brackish water helps these young fish acclimate as they make the transition from river to ocean.
Once at sea, salmon rapidly grow from small freshwater fish into powerful ocean predators. They gain weight quickly, fueled by small fish, including herring, sand lance, and pilchards, as well as squid and crustaceans. Most will spend two to three years migrating across the Pacific Rim, dodging predators such as orcas and sea lions.
As they reach four to five years old, the river will call them home. Salmon are linked to their natal streams. As winter runoff flows from the mouth of the Columbia, it’s time to return.
When adult salmon return to freshwater, they bring the ocean with them. Nearly all of their adult body mass has been gained at sea through years of feeding on smaller fish and other marine creatures. A returning Chinook may carry 12 to 25 pounds or more of this ocean-grown body back into freshwater.
Salmon die shortly after spawning, gifting their bodies to aquatic insects, birds, mammals, and other scavengers. As their carcasses decompose, marine-derived nitrogen and other nutrients enter streams, soils, and plants. Scientists have even traced salmon-derived nitrogen into streamside trees and forest invertebrates.
In this way, salmon blur the boundary between ecosystems. The forest shades and cools the river. Fallen trees create pools and shelter for young fish. Insects from streamside vegetation become food for salmon, and years later, salmon return nutrients gathered in the Pacific to those same rivers and forests.
Forest feeds salmon, and salmon feed our forests.
Holding Steady, With Room to Grow
There is encouraging news in the McKenzie Watershed. A recent study completed by NOAA showed that “most Pacific Coast salmon and steelhead listed under the Endangered Species Act have increased in abundance over the past 25 years.” The research also considered the role of habitat restoration activities, like those on the McKenzie and at haich ikt’at’uu on the coast, in aiding species stabilization and recovery.
Though the changes are leaning positive, the population of spring Chinook salmon in the Upper Willamette remains far below recovery goals, and hatchery-origin fish still make up a significant part of each year’s return.
For a salmon population to sustain itself over the long term, each generation must, on average, produce enough returning adults to replace itself. Over the past decade, that has mostly been true in the McKenzie Watershed. The greater challenge is moving beyond holding the population steady toward a larger, more resilient annual return.
Some of the pressures salmon encounter are enormous and difficult to address locally. Conditions in the Pacific Ocean, including changing temperatures and periods of low ocean productivity, strongly influence whether young salmon survive and eventually return as adults.
But freshwater habitat is something we can improve here at home.
For young salmon, having access to slower, complex off-channel habitat can mean the difference between being swept downstream during high water and finding a protected place to rest, feed, and grow. Restoring side channels, reconnecting floodplains, adding large wood, and giving rivers more room to move create more of these places, giving the next generation more opportunities to survive its first months and years.
One small fish resting behind a log may eventually reach the Pacific Ocean. Years later, it could make its way back into the McKenzie Watershed. And when it does, it will carry the ocean home with it, sustaining an ancient link between forest and sea.
More from the field:
The River Returns to haich ikt’at’uu
After 15 years of planning and development, a major conservation project near the town of Florence has achieved its goal: connecting a large swath of restored farmland to the Oregon Coast. The Siuslaw Estuary is a 217-acre expanse that’s expected to accommodate the return of salmon, lamprey, shorebirds, and native plants as it transforms with the tides.
Restoration Underway at Quartz Creek
McKenzie River Trust and partners broke ground on a major floodplain restoration project on Quartz Creek this May. The project aims to reconnect the creek with its historic floodplain, benefiting the ecosystem and the plants, animals, and people who rely on it.
Partners Resume Restoration on the Siuslaw River Estuary
Partners from the Confederated Tribes of Coos, Lower Umpqua and Siuslaw Indians, the Siuslaw Watershed Council, and McKenzie River Trust are preparing for a second season of restoration on the Siuslaw River at Waite Ranch. Beginning in summer 2023, the tidal restoration project is working to return around 200 acres of estuarine wetlands to the Siuslaw River system.