Seattle City Light said it has filed the Updated Study Report with the Federal Energy Regulatory Commission, an important milestone in the relicensing process for the Skagit River Hydroelectric Project.
The 711 MW Skagit River Hydroelectric Project is a series of three dams and hydro powerhouses that provide 20% of City Light’s power. The three power-generating facilities are Ross, Diablo and Gorge. The operational priorities in order of importance are flood control, downstream fish protection, recreation and power production. The current FERC license for the project expires in 2025.
The utility said this filing is the culmination of 18 months of intense research on the Skagit River, with the results of 33 studies included. Numerous Seattle City Light staff and expert consultants conducted these studies according to the study plan set in July 2021 to better understand and address environmental and other effects of the three-dam system. At the request of its partners, City Light expanded the initial study plan and nearly doubled the funding to $20 million. The studies included:
- Three for recreation
- Eight for water, water quality and river dynamics
- Five for fish
- Six for wildlife and other species
- Four for cultural impacts
- Four for wetlands and plants
- Three for operations
FERC did not require all of the 33 studies for the relicensing process, but they were completed as part of the utility’s commitment to the Tribes and local, state and federal agencies, according to a release. These license partners will use the studies to guide protection, mitigation and enhancement plans as a part of the next license agreement.
Study findings will help inform many future decisions, including operations, flow, environmental restoration projects and recreational opportunities. Here are just a few of the many insights:
- Genetic studies – which help better understand and manage fish – identified a new sub-population of rainbow trout in the upper watershed above Ross Dam, which has likely been in existence for thousands of years.
- The research helped Seattle City Light create new models to help balance flood risk management, water storage and the flows needed to protect healthy salmon down river.
- The utility developed a better understanding of the potential habitat that is available to support fish in the reservoirs.
One of the most asked-about changes to dam operations is around fish passage. Seattle City Light committed to evaluating the feasibility of providing upstream and downstream fish passage at Gorge, Diablo and Ross dams. An aquatic habitat study was included among the 33 studies conducted to address the suitability of fish habitat in Ross Lake. These studies will inform the fish passage program being developed.
As part of its Draft License Agreement filed with FERC in November 2022, City Light laid the groundwork for a comprehensive fish program, including fish passage, that makes improvements to the entire ecosystem. Many other agencies and Tribes will have input into the design and implementation of the fish program, and more work will be done. City Light will include a fish passage program in the Final License Application (FLA) to be filed at the end of April.
Seattle City Light was created by the citizens of Seattle in 1902 to provide affordable, reliable, and environmentally responsible electric power to the City of Seattle and neighboring suburbs.
