Seattle’s three mountain dams generate one-fifth of the city’s power, and a century after they were built engineers now want to create a “water highway” so salmon can reach the other side

Those same dams have supplied Seattle with power since the early 1920s; today they remain one of Seattle’s largest providers of non-carbon emitting energy. However, it has been over a hundred years since the first power was generated from the Skagit River.

During that time, attention has increasingly turned toward salmon that once migrated through the watershed.

Could a river altered by three massive dams ever reconnect with fish that once traveled its upper reaches?

A pathway back to lost habitat

There has existed a barrier to salmon migration for decades. The dams stand between salmon and extensive areas of their upstream habitats.

As a result of this situation, a major relicensing agreement has taken place between Seattle City Light, tribal government entities, state and federal agencies, and others. This relicensing agreement outlines a pathway toward re-establishing a connection between salmon and their historic habitat.

The Skagit Project includes Ross Dam, Diablo Dam and Gorge Dam, as well as lakes, high voltage transmission lines and associated infrastructure extending throughout the entire watershed.

Since 2018, Seattle City Light has worked with partners to develop a new license for the Skagit Project, whose previous federal license expired on April 30, 2025.

After several years of negotiations, the parties involved agreed to a comprehensive settlement outlining how operations of the Skagit Project will be managed for many years to come.

A settlement years in the making

This settlement included provisions related to generating power, managing floods, providing recreational opportunities, meeting tribal requirements, protecting the environment and recovering salmon stocks.

One primary area of emphasis in the settlement relates to fish passage and restoring fish habitat.

Seattle City Light and its partners describe the effort as a comprehensive fish passage program intended to reconnect salmon with historic habitat in the watershed.

The agreement aims to reconnect salmon to areas of the watershed that have been closed off for generations.

Restoring habitat beyond the dams

Salmon are renowned for migrating between oceans and freshwater rivers. Historically, fish migrated through substantial segments of the Skagit Watershed prior to dam construction altering the river system.

Fish passage is identified as one of the central environmental agreements within the relicensing settlement.

In addition to fish passage, the agreement contains plans for estuary and river restoration programs to enhance populations of native fish species and to improve water quality.

Tribal governments participated significantly in negotiations leading up to the settlement. According to Seattle City Light and the Government of Seattle, the agreement represents years of collaborative efforts with the Sauk-Suiattle Indian Tribe, Swinomish Indian Tribal Community, Upper Skagit Indian Tribe, and other agencies and organizations.

The overall framework relies upon ongoing scientific studies, environmental monitoring, and adaptive management processes as the project continues moving forward.

How will salmon reach upstream habitat?

The settlement’s fish passage program is intended to reconnect salmon with parts of the watershed that have been inaccessible for generations. The planned system is expected to transport salmon around the dams.

Young migrating salmon will likely be trucked around the dams, while adult salmon returning from the ocean will be transported above the dams to spawn.

According to Seattle City Light, the comprehensive fish passage program is part of an overarching vision for restoring salmon runs while continuing to produce reliable renewable electricity.

Agreement terms include commitments for fish passage, habitat restoration, long-term monitoring, and continuing cooperation among tribes, agencies, and project operators.

More than 100 years after the first dams were built to supply Seattle with electricity, engineers and river managers are working toward a new phase for the Skagit watershed. Their goal is to help salmon reach parts of the river system that have been inaccessible for generations.