Despite Habitat Improvements Over 20 Years, Spring Chinook In Washington’s Tucannon River Still At Risk Of Extinction, Steelhead Doing Better

Twenty years of habitat improvements on southeast Washington’s Tucannon River are resulting in a mix of outcomes for adult anadromous fish returning to the river, especially over the past few years. Steelhead returns have grown significantly, while spring Chinook salmon returns are far below project objectives and the fish continue to be at serious risk of extinction.

Returns of adult steelhead have grown from about 200 in 2021 to 1,800 in 2024, higher than the project objective of 1,000 returning fish, according to Kris Buelow of the Snake River Salmon Recovery Board, speaking to the Northwest Power and Conservation Council at its November meeting in Portland. The Tucannon River in southeast Washington flows from the Blue Mountains to the lower Snake River near Dayton, emptying into the Snake River between Little Goose and Lower Monumental dams.

However, spring Chinook are returning in numbers far below the 750-fish objective with less than 200 Chinook and 20 redds or nests found in 2023.

There was an upward trend of more adult Chinook in the Tucannon basin between 2008-2015, but a decline began in 2016 that continues today, a Council blog by Peter Jensen says. The Tucannon has the only remaining population of spring Chinook in the lower Snake. The salmon were listed as threatened under the federal Endangered Species Act in 1992. Other listed species in the Tucannon subbasin include fall Chinook, summer steelhead and bull trout.

A July 2022 presentation to the Council by biologists from the Washington Department of Fish and Wildlife explained that “a series of challenges hit in the form of floods; fires; high pre-spawning adult mortality; high juvenile outmigration mortality; predation in the mainstem Snake and Columbia rivers on outmigrants; and changes in marine survival as ocean productivity declines,” the Council blog says.

During the years 1997 to 2002, the state agency implemented a captive broodstock program to help restore the spring Chinook run. However, the produced fish performed lower than expected due to poor egg quality and low fertilization success. The smolt to adult return rates were half of standard hatchery supplementation program survivals.

In 2006, increased hatchery smolt production went from 132,000 to 225,000 fish. In-river pre-spawn mortality increased. There were good returns, lots of fish left in river for natural spawning, but relatively few redds.

From 2016-2022, 100 percent of returning adult fish were captured and held at Lyons Ferry Hatchery on the Snake River for out-planting into the Tucannon. Adult outplants occurred in 2016, 2017 and 2018. No outplants occurred from 2019-2021.

By 2022, when WDFW briefed the Council on Tucannon River spring Chinook, both hatchery and wild fish returns to the river had dropped back to their 1992 levels when they were listed. Smolt to Adult returns for the Tucannon hatchery program are the lowest in the entire Snake River basin.

See CBB, July 14, 2022, CURRENT RECOVERY PLAN NOT WORKING: TUCANNON RIVER SPRING CHINOOK IN BIG TROUBLE, OPTIONS EXPLORED, HTTPS://COLUMBIABASINBULLETIN.ORG/CURRENT-RECOVERY-PLAN-NOT-WORKING-TUCANNON-RIVER-SPRING-CHINOOK-IN-BIG-TROUBLE-OPTIONS-EXPLORED/

This coming year WDFW will release Tucannon spring Chinook hatchery smolts below Bonneville Dam in the lower Columbia as an emergency measure needed to continue to prevent the population from becoming extinct.

The Tucannon project is one of seven habitat “umbrella” projects supported by the Council’s Fish and Wildlife Program. This and the other projects focus on improving ecological function in support of ESA-listed salmonid recovery in the Tucannon River, a Nov. 5 Council Memorandum says (https://www.nwcouncil.org/fs/18971/2024_11_2.pdf). It is administered and coordinated by the Snake River Salmon Recovery Board, which is the Washington regional organization for salmon recovery. The Board is managing the Tucannon River project with the Confederated Tribes of the Umatilla Indian Reservation, Columbia Conservation District, Nez Perce Tribe, US Forest Service and WDFW. The project’s goal is to restore the Tucannon to an “ecologically functioning watershed which possesses resiliency in the presence of future climate changes,” the Memo says.

Under the Northwest Power Act, the Council’s F&W Program relies heavily on protecting, maintaining and improving habitat as an effective means of restoring and sustaining fish and wildlife populations affected by the hydropower system in the Columbia River Basin. The Power Act authorizes offsite mitigation outside the immediate area of the hydro-system, including tributaries and subbasins like the Tucannon.

Originally, as a healthy river, the Tucannon had multiple channels and braids that separated forested islands that divided up flows. “The river had more equilibrium with riparian forests and was more ecologically functional and productive,” Buelow said.

However, there have been more recent changes due to a number of human-caused activities, beginning with commercial timber harvest, followed by channelizing (straightening and diking) the river to aid livestock and agricultural operations, the Council blog says.

The channelizing came about throughout the 1960s after a series of floods caused property and infrastructure damage along the river. The U.S. Army Corps of Engineers supported land managers in straightening and leveeing large sections of the river, confining it to a single channel at a steeper gradient and with increased water speed. From 1967 to 1978, about half of the Tucannon’ s total river length was lost due to channelization and confinement.

The river had become a steep, powerful stream, Buelow said in his presentation, a disconnected river and floodplain with single deep channels, he added.

Work began 20 years ago to restore the river to an ecologically functioning watershed, to bolster its resilience to future climate changes, and to support recovery goals of sustaining 750 returning adult spring Chinook and 1,000 summer steelhead.

The habitat improvements slowed the flow by removing levees and adding woody debris. The intact river now has multiple, braided and shallower channels, the floodplain is reconnected and there is more wetted area, all while increasing the floodplain by as much as 50 percent.

Once the changes are made, then just “Let the river do the work,” Buelow said. The projects create “a lot more space for fish to live.”

In his presentation to the Council, Buelow focused on projects completed over the past five years, as well as those coming up in 2025 and 2026 to 2029. The habitat objectives include floodplain connectivity, channel complexity, reducing stream power and slowing the river, increasing channel length, improving pool frequency and quality, riparian health, and flow and temperature mediation.

The projects completed since 2020 have improved more than five miles of river. An additional 2.3 miles of habitat improvements are planned for 2025 and about 3.4 miles of improvements are planned during the four-year period 2026 to 2029. So far federal, state, tribal and local restoration partners have restored about 15 miles of river since 2010.

For background, see:

— CBB, July 14, 2022, CURRENT RECOVERY PLAN NOT WORKING: TUCANNON RIVER SPRING CHINOOK IN BIG TROUBLE, OPTIONS EXPLORED, HTTPS://COLUMBIABASINBULLETIN.ORG/CURRENT-RECOVERY-PLAN-NOT-WORKING-TUCANNON-RIVER-SPRING-CHINOOK-IN-BIG-TROUBLE-OPTIONS-EXPLORED/

– CBB, Jan. 15, 2021, WASHINGTON STATE SALMON RECOVERY REPORT: MOST POPULATIONS NOT MAKING PROGRESS, SOME ON PATH TO EXTINCTION https://columbiabasinbulletin.org/washington-state-salmon-recovery-report-most-populations-not-making-progress-some-on-path-to-extinction/