City Light Owned Hydroelectric Resources

City Light owns and operates several hydroelectric facilities that typically supply more than half of our customers' power needs. In addition to generating electricity, our facilities provide opportunities for recreational activities such as camping, fishing, and hiking. We are also committed to maintaining our excellent record of regulatory compliance and environmental stewardship, including the support of ongoing programs for the protection of fish, plants, animals and other natural, cultural, and historic resources.

A rainbow forms over the rushing water at Boundary Dam

Hydroelectric Facilities

The Skagit River Hydroelectric Project is located in Whatcom, Skagit, and Snohomish counties in the upper watershed of the Skagit River in the Cascade Mountains. The Project consists of three power-generating facilities - Ross, Diablo, and Gorge - that supply approximately 20% of City Light's electric power. The Project includes over 100 miles of transmission lines from the Diablo Switchyard to the Bothell Substation. 

The operational priorities in order of importance are flood control, downstream fish protection, recreation, and power production. 

In 2003, the Skagit Project was the first large hydroelectric facility in the nation to be certified as a Low Impact Hydropower Project - recognizing it for its commitment to environmental stewardship.

Relicensing the Skagit Project

The Skagit Project operates under a federal license that will expire on April 30, 2025. We are currently collaborating with local partners to develop an application for a new license that will last for the next thirty to fifty years. This includes working with federal and state agencies, Tribes, and other organizations to determine how best to protect the natural and cultural resources of the area for the duration of the new license.

Learn More About Skagit Relicensing

Fish Protection

At the Skagit Project, we adjust flows through the dams on a seasonal, monthly, and daily basis to supply the right amount of water for adult salmon and steelhead when they return to lay their eggs and to protect the young fish when they emerge. We work closely with regional partners to restore and protect habitat that salmon and steelhead need to complete their life cycles.

Wildlife Habitat Protection

We have purchased over 10,000 acres of land dedicated to fish and wildlife habitat preservation, and we provide annual funding for wildlife research and monitoring by the National Park Service and U.S. Forest Service. We converted a historic building into a laboratory to support research on wildlife and vegetation in the North Cascades ecosystem, and our ongoing management of the right-of-way along roads and transmission lines is designed to enhance natural vegetation and increase species diversity.

Learn more about our work to protect the environment

Recreational Opportunities

The Environmental Learning Center on Diablo Lake is supported by City Light with an educational endowment to fund educational programs at the learning center. We also provide funding to build new trails and outdoor learning areas, as well as to build, renovate and maintain recreational trails, campgrounds, and boat launches on lands managed by the National Park Service and US Forest Service. For nearly 100 years we have provided boat tours for visitors to enjoy the beauty of the North Cascades while also learning more about hydroelectricity and the rich history of Seattle City Light.

Learn More About Skagit Tours

Erosion Control

City Light provides funding to the National Park Service to stabilize and replant native vegetation on eroded sites along Ross Lake and Project roads. This reduces sedimentation, protects salmon spawning habitats, and improves the beauty of the area. We also fund the maintenance of a greenhouse to grow native plants for use in landscaping and erosion control.

Cultural Site Protection

We actively protect historic buildings and facilities determined to be eligible for listing on the National Register of Historic Places. To mitigate impacts to cultural and archaeological resources, we work with local Tribes, First Nations, and federal land managers.

Supporting Local Tribes

City Light has supported the Upper Skagit Indian Tribe, Swinomish Indian Tribal Community, Sauk-Suiattle Tribe and Nlaka'pamux Nation for cultural activities and to inventory and protect their traditional cultural properties.

Boundary Dam is located on the Pend Oreille River near the city of Metaline Falls, Washington. The project's federal license includes measures that mitigate the impacts of Boundary's operations on recreational, fisheries, land, cultural, and wildlife resources.

Preserving and Managing Fisheries

City Light implements measures to ensure protection, mitigation, and enhancements of the fisheries located in or around the dam. Measures include innovative research in the 250 square miles of tributaries draining directly into the Boundary Reservoir to guide future actions concerning federally endangered species, and extensive habitat and fisheries restoration. We also stock trout in numerous lakes around the Boundary Project. Trout species consist of west slope cutthroat, rainbow, rainbow triploid, and/or tiger trout. Approximately 12,000 pounds of fish are planted annually.

Learn more about our Tributary Aquatic Habitat Program

Read our Fish and Aquatics Management Plan to learn more.

Land and Wildlife Habitat Protection

We are committed to protecting and enhancing the land and wildlife resources affected by Boundary Project operations. Measures we implement include:

  • Shoreline erosion, monitoring and treatment
  • Weed management
  • Protection of rare, threatened, and endangered plants
  • Wildlife monitoring
  • Management of Project Habitat Lands that provide areas for a variety of wildlife species
  • Environmental awareness and education for staff and recreationists

Read our Terrestrial Resources Management Plan to learn more.

Cultural Resource Preservation

We work in partnership with the U.S. Forest Service, Bureau of Land Management, Bureau of Indian Affairs, and Kalispel Tribe of Indians and consult with the Washington Department of Archaeology and Historic Preservation and the Federal Energy Regulation Commission to protect cultural resources throughout the Boundary Project area. The measures we implement include:

  • Evaluating proposed activities for their potential to affect historic properties
  • Monitoring cultural site conditions
  • Conducting archaeological surveys
  • Implementing site protection and data recovery activities

In 2018, the Boundary Project was listed on the National Register of Historic Places

Recreational Opportunities

The Boundary Project occupies a highly scenic, uncrowded setting that offers many outdoor recreational opportunities, including boating, fishing, sightseeing, picnicking, camping and much more.

  • Boundary Dam tours offer a look into the massive limestone cavern where our Visitor's Gallery is located.
  • The Forebay Recreation Area at Boundary Dam is now open after substantial improvements to the campground, day use area and boat launch. It offers 22 campsites (including RV and car sites), flush toilets and potable water areas with hook-ups, dump stations and showers. Sites also have fire rings and picnic tables, as well as BBQ grills and a boat launch.
  • The Metaline Waterfront Park, owned and operated by the town of Metaline, has been updated by City Light and now includes a boat launch, boarding float, kayak ramp and parking. Also added is a new group shelter with fire pit, playground equipment, a restroom building, landscaping and a wooden bridge across Linton Creek that runs through the middle of the park. All improvements were built with accessibility in mind.
  • The Vista House, built in 1965, provides panoramic views of the dam and surrounding landscape. It provides interpretive displays, restrooms, and a picnic area.
  • Additional recreational sites along the reservoir shoreline provide opportunities for camping, fishing and day use. City Light is developing a new portage trail near the falls in 2022 to provide non-motorized boaters an alternative to avoiding the rapids at the falls.
  • The canyon reach area of the reservoir between Metaline Falls and Boundary Dam offers spectacular views of geology and steep rock faces, wildlife, dense forest vegetation, nearby mountains and waterfalls (including Peewee Falls). City Light is constructing two new viewpoints and trailheads along the eastern ridge of the canyon, complete with parking and restrooms by 2021. For hiking enthusiasts, we are also constructing a new 4-6-mile trail connecting the Peewee Falls and Riverside Mine Canyon viewpoints by 2023.

For more information about recreational opportunities, please call (509) 446-3083 and select option 9, or email us.

Located in east King County in the Cascade Mountains, the Cedar Falls Hydroelectric Project was City Light's first hydroelectric plant built to light the streets of Seattle. It was also the nation's first municipally owned hydroelectric project. Started in 1902, it was finally completed in 1914 and included the Masonry Dam, penstocks, powerhouse, and a company town. The Masonry Dam that creates the Chester Morse Reservoir is used for power generation while also providing about 70% of the domestic water supply to the Seattle metropolitan area of approximately 1.4 million people.  Water flow from the reservoir is also managed to provide favorable instream flow conditions for salmon and steelhead reproduction.

The stream flows are managed under the City of Seattle Cedar River Watershed Habitat Conservation Plan (HCP).

Cultural Resource Protection

The Cedar Falls Project is located within two National Register listed districts - the Seattle Municipal Light and Power Plant and the Cedar River Watershed Cultural Landscape. City Light actively protects cultural resources in the project area, as well as helping to mitigate impacts to these resources. We partner with Seattle Public Utilities, local Tribes, federal, state and county agencies in the management of cultural resources.

The South Fork Tolt River Hydroelectric Project is City Light's newest hydro facility. It was completed in 1996 to leverage the Seattle Public Utilities Tolt Reservoir and Dam that has been providing approximately 30% of the drinking water to the metropolitan Seattle area since 1964. The Tolt is an earthen dam located on the South Fork Tolt River in the foothills of the Cascades in east King County and is upstream of a water fall that is a natural barrier to fish passage.

While Seattle City Light's South Fork Tolt hydroelectric facility supplies less than 1% of Seattle City Light's power requirements, it is an important source of renewable energy for the utility.

Tolt Project License

The current license (FERC Project No. 2959) for the South Fork Tolt River Hydroelectric Project was initially issued in 1984 by the Federal Energy Regulatory Commission. Federal and state agencies and the Tulalip Tribes filed motions with FERC to intervene in the relicensing procedure focusing primarily on the need to provide adequate long-term provisions for flows, habitat restoration and monitoring. City Light filed a settlement agreement in 1988 which included fish and wildlife protection measures and mitigation jointly signed by the City, state and federal fish and wildlife agencies, and Tulalip Tribes. The agreement was accepted by the FERC, incorporated into the license and the stay was lifted in 1989. The forty-year license will expire in July 2029.

The Tolt Fish Advisory Committee (TFAC), which is comprised of the parties that negotiated the Settlement meets on an as-needed basis to oversee implementation of and compliance with license required mitigation and related operations. 

Fish Protection

City Light works in partnership with Seattle Public Utilities and the TFAC to ensure protection, mitigation and monitoring of fish located downstream of the dam. This work includes:

  • Adjusting flows from the dam on a seasonal and monthly basis to provide the right amount of water for fish to access habitat, spawn, and rear in the South Fork Tolt River
  • Decreasing flows at the Dam or at the project slowly, so fish can sense the change and move safely to deeper water preventing them from getting trapped
  • Ensuring water is continuously passed to the river, even when the project trips offline
  • Monitoring water quality
  • Conducting studies and research with a focus on salmon and steelhead to guide decisions on their protection, to better understand the South Fork Tolt River as their home, and assist in defining restoration actions
  • Implementing fish habitat projects with a focus on improving river process, like placing large wood in the South Fork Tolt in the form of jams 

Watch a video highlighting our research

Read one of our published reports

Watch a video highlighting one of our fish habitat projects

Recreational Opportunities

The Tolt Project is located inside the City of Seattle's Municipal Watershed that supplies Seattle and surrounding communities with drinking water. To maintain high-quality drinking water the area is closed to the public and recreation. To make up for this, City Light provided financial support to King County Parks to assist in the development of the Moss Lake Natural Area and to the USFS for the development of the Middle Fork Snoqualmie Trailhead and parking lot.

Cultural Site Protection

We actively protect cultural resources within the project area per the terms of the Tolt FERC License in partnership with Seattle Public Utilities, local Tribes, and federal, state, and county land managers.

Land and Habitat Protection

We are committed to protecting and enhancing our land and habitat in the Tolt Basin. Above the reservoir, the City of Seattle successfully exchanged lands within the South Fork Tolt Watershed in 1977 with Weyerhaeuser Company, giving Seattle 70% ownership (approximately 8,400 acres) of the land that supplies the water. The eastern 30% lies in the Mt. Baker-Snoqualmie National Forest. Seattle Public Utilities (SPU) manages these lands. You can learn about SPUs South Fork Tolt Municipal Watershed Management Plan for the Tolt watershed upstream of the dam.

In the Tolt/Snoqualmie Watershed downstream of the dam, City Light's Endangered Species Act Land Program purchases land that supports quality Chinook and steelhead habitat. The lands in the program were purchased with City Light and grant funds. Working with partners we also actively restore habitat that benefits both fish and wildlife in the basin.

The Newhalem Powerhouse is a small, run-of-river hydropower facility originally constructed in the 1920's to provide power to build the Gorge Dam and Powerhouse, and the associated construction camp. The project is located entirely on federal lands on Newhalem Creek, a small tributary to the Skagit River, which enters the river downstream of City Light's Skagit River Project. When operational (typically during late fall, winter, and spring when creek flows are highest) the Powerhouse can produce 2MW of power. Today, the project is primarily used as a source of emergency power for the Skagit River Project and associated facilities.