Giving the Molalla River a Chance

Guest Post by Luke Whitman and Ben Walczak of Oregon Department of Fish and Wildlife

Historic land use practices have taken their toll on native fish in the Molalla River, especially salmon and steelhead. The Molalla River used to support a native run of spring Chinook salmon, with as many as 8,000 wild adults coming back to the river. In the 1940s, the run was estimated between 1,000-1,500 fish. By 1953, only 760 fish came back. Numbers declined steadily during the 1950s and 1960s after many years of intense logging in the drainage, in addition to overfishing and pollution in the Willamette River. The native run of spring Chinook in the Molalla River was gone by the late 1970s. Spring Chinook salmon from the Willamette River were federally listed as threatened under the Endangered Species Act in 1999.

The lower Molalla River still has problems, such as low water from withdrawals, high temperatures in the summer, and fewer side channels. ODFW and the Native Fish Society have done surveys off and on since 2000, finding little natural production of spring Chinook salmon. Poor ocean conditions in recent years have contributed to low returns. A few years ago, ODFW started doing more work to monitor steelhead in the upper Molalla River, also with help from the Native Fish Society. The steelhead surveys showed us how much good habitat is still available for spring Chinook salmon in the upper basin. We decided it was worth taking a chance to bring wild Chinook back to the Molalla River.

The much different habitat in the upper and lower Molalla gave us a unique opportunity to learn more about what limits recovery of native salmon. We designed a study to find the best habitat for spring Chinook salmon and to see if we could get them to come back on their own. We reached out to Olympic Resource Management and Weyerhaeuser, who both gave us permission to access areas where we wanted to release spring Chinook. We decided to release both adult and juvenile spring Chinook into the upper Molalla River for three years to give us the best chance for success.

The first 100 adult spring Chinook salmon that returned to the Minto Fish Facility on the North Santiam River were held separately to be used in this study. Starting in the fall of 2019, some of these adult salmon were spawned and the eggs were sent to the Fish Performance and Genetics Lab at Oregon State University (OSU). Researchers at OSU have found a way to raise salmon that better prepares them for life in the wild. These fish are fed a special food, so they grow slowly, and are spread out in tanks with structures that resemble stream habitat. They are even taught how to avoid predators. Spring Chinook fry from this program were used for the Molalla study so they would have the best chance at survival. Groups of 6,000 juvenile Chinook were released into three different areas at the end of May; the North Fork Molalla, Table Rock Fork, and the upper Molalla River near Copper Creek. Each group had 2,000 fish that were tagged with microchips (like those used for pets) so we can follow their movements. Underwater receivers at different sites will read the microchip tags as the fish swim by. This will help us understand how these fish survive their journey from the Molalla River to the Pacific Ocean and back again as adult salmon coming over Willamette Falls.

Each fall after the juveniles were released, we also released adult spring Chinook from the North Santiam River into the Molalla River. In 2020, we released them at the “Bee Ranch” property where Table Rock Fork meets the Molalla River. In 2021, we released adult salmon in the upper river near where Copper Creek comes in. For 2022, we plan to again release the adults near Copper Creek.

The wildfires in 2020 caused many changes in the upper basin, which we believe will help the river long-term. Many trees have been added to the river and tributaries naturally, increasing habitat complexity, and more gravel has come into the river from faster erosion after the fires. Building on these natural changes, large restoration projects are planned for the next several years. These projects will add more logs and gravel to areas in need and connect side channels. All of this together will provide more habitat for spawning salmon and juveniles rearing through the year. Also, this work will help native winter steelhead.

While the recent changes may help the upper Molalla River, we do not know if it will be enough to overcome problems in the lower river. The extreme weather we have seen in recent years is a major concern. Spring Chinook salmon need enough water to migrate in the spring and hold through the summer before they spawn in the early fall. Warmer conditions may help non-native fish like smallmouth bass and channel catfish move into more areas, while reducing habitat for salmon and steelhead.

Given the hardships facing the Molalla River, it is encouraging that wild steelhead continue to return. We believe that native spring Chinook have a chance to do the same again. We will continue to help these fish along by releasing them where we can and studying their survival. Also, we will keep working with our partners to improve habitat and monitor the changes taking place. With hard work and a little luck, all of these changes may make the Molalla River a better place for wild steelhead and salmon.