Keeping local waters habitable for salmon
High water temperature is a deadly threat to salmon.
Long Live the Kings and the Lake Washington/Cedar/Sammamish Watershed (WRIA 8) Salmon Recovery Council are partnering to solve this unique challenge and support salmon survival.
Salmon at Risk
Lake Washington sockeye salmon, once the largest sockeye run in the Lower 48, are on the verge of collapse.
Chinook salmon are listed as “Threatened” under the Endangered Species Act. Over $125 million has been spent restoring fish access and habitat upstream in the basin of the Ship Canal. All of this may be in vain if water temperature in the Ship Canal continues to increase.
Each summer, sockeye, coho, and threatened Chinook salmon battle worsening conditions on their journey through the heart of Seattle. Hot water temperatures in Lake Washington Ship Canal can be lethal to salmon and only a fraction of salmon reach their spawning grounds in the Cedar and Sammamish Rivers. These Pacific Northwest icons are on a path to extinction in and it’s happening in Seattle’s backyard.
To save these salmon we need to understand the deadly challenges they’re facing, come together, and act before it’s too late.
Warm water weakens salmon
High temperatures in our lakes are getting worse
High water temperatures have been a problem in the Lake Washington Ship Canal for more than two decades, and the problem is only getting worse.
During the June 2021 heat wave, when Seattle reached a record-breaking 108°F, dead sockeye were found around the Ballard Locks fish ladder.
The 2021 heat wave is not an isolated incident. Climate change is causing increasing average annual temperatures and extreme weather events. Extreme temperatures have a generational ripple effect in struggling salmon populations. Even if they can survive to reach their spawning grounds, fish weakened from high temperatures may be less successful in reproducing. These issues will continue to worsen as the impacts of climate change persist.
The warmer water also provides favorable conditions for invasive fish that eat young salmon. There are a few deeper locations in the Ship Canal with colder water, but they often don’t have enough oxygen for the fish to survive. At the Ballard Locks, migrating salmon must transition between cold saltwater and hot freshwater within a few hundred yards. These changes have major impacts on juvenile and adult salmon, including delayed or blocked migration, higher mortality due to increased susceptibility to diseases, fungi, and parasites, and even death.
A Group Effort
The Lake Washington Ship Canal is a Unique Challenge
Typical salmon passage and typical actions, like planting trees for shade, aren’t practical solutions in this area. To save these beloved salmon runs, we will need innovative ideas and community-wide investment to bring cooler waters to the Ship Canal.
In 2020, we convened a team of government and community partners to review the science and evaluate possible solutions to help salmon pass safely through the Ship Canal. Phase 1 of the project focused on reviewing the science and prioritizing promising solutions for further analysis. In Phase 2, which began in 2023, the group is completing an initial feasibility analysis, pursuing water temperature modeling, developing strategies to implement solutions, and supporting ongoing work. Phase 3 will put these solutions into action.
The goal is to create a continuous pathway or connected pockets of water within the Ship Canal where water temperatures and dissolved oxygen levels are within the healthy range for salmon, allowing them to migrate freely.
At the same time, urgent short-term solutions are necessary to keep the salmon runs from collapsing while a long-term fix is in progress. These actions could include changes to operations and redesigning fish passage at the Ballard Locks, where adult salmon face the difficult transition from cool saltwater to warm, low-oxygen freshwater in the Ship Canal.
As Seattle’s summers get warmer, experts agree that we need to pursue multiple strategies to prevent the extinction of these salmon runs, now and for generations to come.