Relicensing the South Fork Tolt Hydroelectric Project

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South Fork Tolt Reservoir and Dam Aerial View

Project Description

The City of Seattle owns and operates the South Fork Tolt Hydroelectric Project (Project) under a license administered by the Federal Energy Regulatory Commission (FERC). Through Seattle City Light and Seattle Public Utilities, the City is working to relicense the Project and will be working closely with federal and state agencies, Tribes, and other licensing participants throughout the multi-year relicensing process.

The 16.8-megawatt Project is City Light’s newest hydroelectric facility. The Project was completed in 1995 to generate electricity from the existing Tolt Reservoir and Dam, which are owned and operated by Seattle Public Utilities to provide about 30-40% of the drinking water supply for 1.5 million people in the greater Seattle area.

The City's goal for the relicensing process is to obtain a new FERC license that enables City Light to continue to deliver affordable, reliable, and environmentally responsible energy services to our customers in a manner that maintains the City's long-term water supply. While the Project supplies less than 1% of City Light's power requirements, it is an important source of renewable energy for its customers. It powers the Tolt Water Treatment Facility and helps balance out the power provided by other renewable sources in the region, thus filling in gaps and increasing resiliency within the local power grid.

FERC issued the City its initial license for the Project in the 1980s. This 40-year license will expire in July 2029. The City will formally initiate the relicensing process with the filing of its Notice of Intent (NOI) to relicense the Project and Pre-Application Document (PAD) no later than July 19, 2024. Following submittal of the NOI and PAD, the City will work with licensing participants and interested parties to develop and implement relicensing studies, which will inform the City’s application for a new license to be filed no later than July 19, 2027.


The Project is located on the South Fork Tolt River, approximately 35 miles east of the city of Seattle in the foothills of the Cascade Mountains, near the towns of Carnation and Duvall. All Project facilities are located within unincorporated King County on the South Fork of the Tolt River, which merges with the North Fork Tolt River below the Project to form the Tolt River, a tributary to the Snoqualmie River.

Community Benefits

Issuance of a new FERC license will allow the City to continue producing clean, carbon-free energy from the Project for the next 30-50 years. Through the relicensing process, the City will coordinate with licensing participants and interested parties to develop proposed protection, mitigation, and enhancement measures for inclusion in the new license to benefit environmental and cultural resources impacted by the Project during the new license term.

What's Happening Now?

Project Update (Fall 2023): During the spring and summer of 2023, the City conducted initial outreach and meetings with interested licensing participants and interested parties. Over the fall, resource working groups were formed, comprised of City staff and licensing participant representatives. Concurrently, the City is working to develop the NOI and PAD, which is expected to be filed in early 2024.

South Fork Tolt FERC Relicensing Schedule

High-Tech “Spherical” Video of the South Fork Tolt Project

This interactive spherical video provides an opportunity to view the hydroelectric project and its facilities, the Tolt Reservoir and Dam, and the South Fork Tolt River as it joins the Tolt River and enters the Snoqualmie River.

City Light

Dawn Lindell, Interim General Manager and CEO
Address: 700 5th Ave, Seattle, WA, 98104
Mailing Address: PO Box 34023, Seattle, WA, 98124-4023
Phone: (206) 684-3000

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.