Lake Washington Ship Canal Sustainable Rivers Project
The U.S. Geological Survey (USGS) and the U.S. Army Corps of Engineers (USACE) are refining a water quality model to better understand temperature and salinity dynamics in the Lake Washington Ship Canal and evaluate conditions for migrating salmon. This effort supports the Sustainable Rivers Program, balancing navigation, water management, and ecosystem health.
For over a century, the Lake Washington Ship Canal (LWSC) and Ballard Locks have shaped the flow of water in Seattle, linking Lake Washington to Puget Sound. Constructed in 1916, this navigation project artificially connected bodies of water and transformed the surrounding ecosystem in ways both intentional and unexpected. The redirection of the Cedar and Sammamish Rivers, the lowering of Lake Washington by nine feet, and the conversion of Salmon Bay from a brackish estuary to a freshwater environment forever altered the region’s natural hydrology.
Today, the U.S. Geological Survey (USGS) and the U.S. Army Corps of Engineers (USACE) are working together to inform LWSC management strategies and their effects on salinity, water temperature, and other variables. This effort is critical for the survival of native salmon and steelhead, which must navigate the Ship Canal during migration. With Chinook salmon, steelhead, and bull trout listed as threatened under the Endangered Species Act, scientists and water managers are looking for solutions to improve conditions for these cold-water fishes.
A changing waterway and its effects on fish
Each summer, as boats pass through the Ballard Locks, saltwater seeps into the freshwater system, pushing upstream toward Lake Union and the Montlake Cut. At the same time, the LWSC has warm temperatures in the summer, creating a stressful environment for cold-water fishes. These species rely on cool, oxygen-rich water, but as temperatures climb, their stress levels increase, making migration more difficult and survival uncertain. Finding a way to reduce thermal stress on migrating fish is not just an ecological concern—it’s a critical step toward preserving the region’s natural heritage.
Using science to guide solutions
To address this concern, USGS was asked to review and update the USACE's existing CE-QUAL-W2 model for water temperature and salinity. CE-QUAL-W2 simulates water movement, temperature, and salinity throughout the LWSC. The model provides a way to test different management strategies, helping scientists and engineers predict how changes in water flow or infrastructure might improve conditions for fish.
The USGS is reviewing and updating this model, to ensure it accurately represents observed conditions. Through a detailed review process, scientists will assess how well the model captures key environmental factors and identify opportunities for improvement. The goal is to release an updated model that can help decision-makers explore different approaches—whether that means adjusting water releases, modifying the locks' operation, or even considering new infrastructure solutions.
This collaborative effort is part of the broader Sustainable Rivers Program, a partnership between USACE and The Nature Conservancy aimed at modernizing water management to benefit both people and ecosystems. By applying cutting-edge scientific modeling, resource managers will be better equipped to make informed decisions that support both waterway operations and the fish that depend on them.
The U.S. Geological Survey (USGS) and the U.S. Army Corps of Engineers (USACE) are refining a water quality model to better understand temperature and salinity dynamics in the Lake Washington Ship Canal and evaluate conditions for migrating salmon. This effort supports the Sustainable Rivers Program, balancing navigation, water management, and ecosystem health.
For over a century, the Lake Washington Ship Canal (LWSC) and Ballard Locks have shaped the flow of water in Seattle, linking Lake Washington to Puget Sound. Constructed in 1916, this navigation project artificially connected bodies of water and transformed the surrounding ecosystem in ways both intentional and unexpected. The redirection of the Cedar and Sammamish Rivers, the lowering of Lake Washington by nine feet, and the conversion of Salmon Bay from a brackish estuary to a freshwater environment forever altered the region’s natural hydrology.
Today, the U.S. Geological Survey (USGS) and the U.S. Army Corps of Engineers (USACE) are working together to inform LWSC management strategies and their effects on salinity, water temperature, and other variables. This effort is critical for the survival of native salmon and steelhead, which must navigate the Ship Canal during migration. With Chinook salmon, steelhead, and bull trout listed as threatened under the Endangered Species Act, scientists and water managers are looking for solutions to improve conditions for these cold-water fishes.
A changing waterway and its effects on fish
Each summer, as boats pass through the Ballard Locks, saltwater seeps into the freshwater system, pushing upstream toward Lake Union and the Montlake Cut. At the same time, the LWSC has warm temperatures in the summer, creating a stressful environment for cold-water fishes. These species rely on cool, oxygen-rich water, but as temperatures climb, their stress levels increase, making migration more difficult and survival uncertain. Finding a way to reduce thermal stress on migrating fish is not just an ecological concern—it’s a critical step toward preserving the region’s natural heritage.
Using science to guide solutions
To address this concern, USGS was asked to review and update the USACE's existing CE-QUAL-W2 model for water temperature and salinity. CE-QUAL-W2 simulates water movement, temperature, and salinity throughout the LWSC. The model provides a way to test different management strategies, helping scientists and engineers predict how changes in water flow or infrastructure might improve conditions for fish.
The USGS is reviewing and updating this model, to ensure it accurately represents observed conditions. Through a detailed review process, scientists will assess how well the model captures key environmental factors and identify opportunities for improvement. The goal is to release an updated model that can help decision-makers explore different approaches—whether that means adjusting water releases, modifying the locks' operation, or even considering new infrastructure solutions.
This collaborative effort is part of the broader Sustainable Rivers Program, a partnership between USACE and The Nature Conservancy aimed at modernizing water management to benefit both people and ecosystems. By applying cutting-edge scientific modeling, resource managers will be better equipped to make informed decisions that support both waterway operations and the fish that depend on them.