LIHI Certificate #5 - Skagit Project, Washington

Project Name Skagit
LIHI Certificate No. 5
LIHI Certificate Term May 15, 2016 – May 15, 2031
Owner Seattle City Light
State Washington
Location Located between river mile 97 and 105 on the Skagit River in northeastern Puget Sound, Washington
Installed Capacity Total: 805.4 MW
Gorge Powerhouse: 173 MW
Diablo Powerhouse: 182.4 MW
Ross Powerhouse: 450 MW
Average Annual Generation 2,349,793 MWh (5-year ave)
Facility Type store and release
FERC No. P-553 issued in 1995, expires 04/30/2025

The Skagit Project is located within the Ross Lake National Recreation Area (RLNRA) on the Skagit River in Whatcom County in northwest Washington. The RLNRA is managed by the National Park Service (NPS) and the Skagit River is classified as a Wild and Scenic River for its outstanding fisheries, wildlife, and scenic quality. The Skagit River runs 150 miles east-to-west from its headwaters in the Canadian Cascades of British Columbia to Puget Sound near Mount Vernon, Washington, draining 1.7 million acres along its route. Snowmelt from the mountain ranges in British Columbia and Washington provide a source of cool water that offers abundant fish habitat. Outside of Alaska, this region is the most heavily glaciated region in the U.S. and is also one of the snowiest places on earth, according to the NPS.

In the early 20th century, demand for municipal power soared in the Seattle region. In 1910, Seattle City Light (SCL) was founded as a separate lighting department to provide electric utility services to the region, and J.D. Ross, a self-taught engineer and second superintendent of SCL pushed ahead with the goal of harnessing the power of the Skagit River through a series of three dams. Ross and SCL received approval from the federal government in 1918 and began to construct a railroad to transport workers to the remote site of Newhalem, where workers would live while they worked on the first dam, the Gorge Dam. The three dams were constructed sequentially over 40+ years to meet growing power demands for the City of Seattle, with completion dates in 1924 (Gorge Dam), 1936 (Diablo Dam), and 1952 (Ross Dam). Power began generating from the final project in 1952, marking the conclusion of the Skagit Project and the nearly 50-year construction project it supported. The project now provides one-fifth of SCL’s power needs.

In 1991, the project owner completed a Settlement Agreement with various stakeholders which included additional flow management, aquatic habitat enhancement, recreational facility improvement, revegetation, historic and cultural resource protection, and compensation to Native American tribes. This agreement was revised several times, most recently in 2011. Further, the current agreement organized three committees to implement the terms of the settlement. They are the Wildlife Lands Acquisition Group, Flow Plan Coordinating Committee (FCC), and the Nonflow Plan Coordinating Committee (NCC). The members of these committees include the NPS, US Forest Service, US Fish and Wildlife Service (USFWS), National Marine Fisheries Service, Upper Skagit Tribe, Sauk-Suiattle Tribe, Swinomish Indian Tribal Community, Washington Department of Fish and Wildlife, and Seattle City Light.

The project is comprised of three separate facilities:

  1. Ross Dam is a 540-foot-high concrete arch dam with two 24.5-foot-diameter, 1900-foot-long concrete power tunnels. The power tunnels convey water to four vertical type Francis turbines with a combined capacity of 450 MW.
  2. Diablo Dam is a 300-foot-high concrete arch dam with one 19.5-foot-diameter, 1900-foot-long concrete power tunnel. Water is conveyed to the powerhouse via two 15-foot-diameter, 290-foot-long steel lined penstocks. The powerhouse contains four vertical Francis turbines with a combined capacity of 182.47 MW.
  3. Gorge Dam is a 300-foot-high concrete arch and gravity dam with one 20.5-foot-diameter, 11,000-foot-long concrete power tunnel, leading to four penstocks controlled by butterfly valves. The powerhouse contains four vertical Francis turbines with a combined capacity of 173 MW.

Ross Dam impounds Ross Lake, the largest and uppermost reservoir at the project. This 24-mile-long reservoir extends into Canada and consists of the primary water storage system for the project, and is used for flood control, power generation, fishery protection, and recreation. Ross Dam is drawn down in fall and winter make room for spring glacial melt and runoff to support flood control efforts. Four miles downstream of Ross Dam, the Diablo Dam impounds the 4.5-mile-long Diablo Lake. Water levels in the lake are maintained primarily for daily and weekly regulation of flows coming from the Ross powerhouse. Diablo Lake is particularly well-known for its brilliant bright turquoise color, a result of suspended powder from ground rocks due to the surrounding glaciers. The Gorge Dam impounds Gorge Lake, the smallest and furthest downstream development at Skagit. Located 4 miles downstream from Diablo, the reservoir fluctuates only several feet and flows are regulated by operating conditions at Diablo and Ross dams. The project operates in a store and release mode, with flows highly regulated by the FCC. Flows are adaptively managed annually based on precipitation, river level, tributary flows, and seasonal runoff, all meant to promote successful salmon and steelhead populations throughout all stages of their life cycle.

PLUS-Standard: The project modifies operation of the facility based on real-time information collected by its biologists, implementing numerous and voluntary non-flow habitat enhancements. The net benefits are also demonstrated by the steadily increasing proportion of Skagit Chinook salmon spawning since 1991, with an average of 78% of all fall/summer Chinook spawning in this region (~8,000 fish). Washington Department of Fish and Wildlife considers the Chinook salmon stock “healthy,” and this basin features the most abundant run of naturally spawning Chinook in the Puget Sound region. The Skagit River System Cooperative (the fisheries and environmental group for the Swinomish and Sauk-Suiattle Tribes) noted that “tangible benefits observed while working with SCL to implement their license include routinely providing additional flow beyond their minimum requirements to provide a higher level of incubation and emergence success of salmon and steelhead as well as funding research that has increased the scientific knowledge of fish and fish habitat specific to the basin.”

Waters within the project reach are designated as Category 1 and Category 2, the highest water quality standards in the state. The waters are highly suitable for aquatic biota and wildlife habitat as well as recreation. The project owner has supported water quality monitoring activities in Ross Lake and six tributaries. The monitoring assesses threats from land-use practices, climate change, and atmospheric depositions. Four of these monitoring stations are located along Ross Lake and provide continuous data on water temperature and chemistry, chlorophyll-a, and zooplankton. The data help guide management actions, especially with the presence a threatened and endangered species in the reservoir.

The Skagit River is a critical region and focus of fish recovery in the Puget Sound region with abundant populations of Pacific salmon (chinook, coho, pink, chum, and sockeye) and three anadromous species: steelhead, sea-run cutthroat trout, and sea-run dolly varden. Historical evidence indicates that populations of steelhead and salmon likely never made it past the natural migratory barriers of turbulent rapids and waterfalls in Gorge Canyon. Critical habitat for spawning salmonids and steelhead exists downstream of the Gorge powerhouse and operational flows are designed to support these species and their habitat.

Ross Lake is home to the largest-known population of bull trout (a federally threatened species) in the contiguous US, due in part to the cold-water conditions from ice and snowmelt that provides suitable summer habitat conditions. The reservoir level is managed to provide flood control, ensure recreation in the summer months (generally maintained at full pool), accommodate snowmelt from surrounding mountains and glaciers and releases as needed for downstream fishery protection and power generation. The project owner has also implemented programs to support trout habitat and increase population numbers in the Gorge and Diablo reservoirs.

PLUS-Standard: The project has an adaptive management program in place that guides management actions to support anadromous fish on a real-time basis. The monitoring program includes the following elements: (1) annual field monitoring surveys to measure any adult chinook and steelhead take during spawning low flow periods; (2) surveys conducted every ten days during spawning periods to document the number of redds (spawning nests) dewatered due to project operations; and (3) estimates of chinook and steelhead fry stranding take due to flow fluctuations. Further action that informs the management actions are contained in the Revised Fisheries Settlement Agreement in 2011, which provides key formulas and methods for adjusting project flows on a real-time basis to promote healthy anadromous fish reproduction downstream.

The project lands consist of 191 acres. However, the project owner collectively owns, protects, and manages almost 14,000 acres of habitat below the facility. These lands are managed for fishery protection, wildlife mitigation, and endangered species protection. The project owner provides funding for several river and habitat restoration programs. Further, the project lands were assessed for habitat enhancement efforts. Efforts were focused on riparian areas and corridors, wetlands, and mature forest communities. The Skagit facilities are surrounded by the North Cascades National Park, which includes a temperate rainforest on the western side and a ponderosa pine forest on the eastern side and features over 300 glaciers. Roughly 70% of the basin is under federal administration as designated wilderness and/or national park. The topography changes from mountainous regions to floodplains and rolling uplands as the Skagit River approaches Puget Sound. The estuaries and tidal flats located in these downstream reaches attract numerous migratory bird species, including snow geese and trumpeter swans. According to the federal agencies that manage the Wild and Scenic Rivers Program, the Skagit river is “the largest and most biologically important river draining to Puget Sound” and is immensely popular for recreation activities.

Threatened or endangered species potentially present in the project vicinity include the grey wolf, grizzly bear, Canada lynx, Northern spotted owl, marbled murrelet, bull trout, steelhead, and Chinook salmon. Wolf populations were nearly eliminated from Washington by 1930 but have made a steady recovery. Individuals are regularly sighted around Ross Lake, but there are no impacts to the species from project operations. Though bear habitat is potentially found on project lands, very few individuals have been found in the Cascade Mountains. Project operations do not impact the bear species. Canada lynx habitat in the state is primarily located in high elevations and east of the Skagit reservoirs. Depending on old forests, the species is threatened by logging and development, though their habitat lies far outside the lower altitudes of the project. The Northern spotted owl prefers dense forest, potentially including the Ross Lake National Recreation Area, though the species is not known to nest in the area and no critical habitat is present in the project area. The marbled murrelet, a seabird, typically ranges within 40 miles of the ocean, with a maximum extent of 55 miles inland. The project area lies 60+ miles from the ocean. The project owner does manage lands that have potential habitat for the species, but this lies outside of the project area.

PLUS-Standard: The project owner maintains a monitoring program for bull trout including by conducting radio telemetry and spawning surveys and has funded significant research on trout populations in collaboration with state, federal, and Canadian partners. Further, the project owner conducts annual surveys of the drawdown zone and transitory barrier removal to allow fish to access feeder tributaries.

The project supports many cultural and historic resources. The reach downstream of the Gorge powerhouse in the town of Newhalem contains many structures listed on the National Register of Historic Places (NRHP). The town was constructed to house workers building the Skagit project. Several archaeological sites exist downstream and the project owner has provided funding to three Native American tribes to conduct their own confidential inventories of cultural resources. The Diablo and Ross dams and powerhouses are listed on the NRHP. Ross Lake supports 144 prehistoric sites and 67 isolated prehistoric artifacts or features. The sites indicate the subsistence of the aboriginal Native American tribes, including hunting, gathering, and fishing. The Upper Skagit River Valley Archeological District was listed on the NRHP in 2004. The area exhibits nearly 10,000 years of settlement in the area by indigenous people groups. The project owner has worked to enhance educational opportunities on historical uses of the sites and surveys, tests, and evaluates the status of the sites and any maintenance needed.

Recreational resources at the project include boating, fishing, hunting, camping, climbing, and hiking. The project owner has provided $17 million to construct and maintain recreation facilities along the Skagit River in collaboration with NPS and USFWS. Additionally, the project owner provided $9 million to construct the North Cascades Environmental Learning Center which offers multimedia and research opportunities, laboratories, and dining/lodging facilities for almost 100 guests. Public access is provided free of charge where safe.

Compliance Status

The Certification includes the following condition:

  • Condition 1: The current FERC license for the facility will expire on April 30, 2025, before the end of the 10-year term of the new LIHI Certificate. LIHI Certification does not imply any judgment or recommendation on what the terms of future FERC licenses should be. If the facility owner executes one or more comprehensive Settlement Agreements (SA’s) with stakeholders, receives a new state Water Quality Certification (WQC), or receives a new FERC license before the end of the new LIHI certification term, the facility owner shall provide LIHI with notification of that fact within 30 days of the relevant issuance, and describe all differences between the previous requirements and new requirements under the new FERC license, new SA’s, or new WQC conditions that are relevant to the LIHI Criteria. LIHI staff will review those differences and decide whether the project continues to meet the LIHI Criteria and whether any changes will be required to the current LIHI Certificate. LIHI reserves the right to modify its certification of the facility to maintain consistency with future FERC and state requirements and all agency recommendations therein.

2023: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.  For Condition 1, the project reported no changes. On March 7 2023 the updated study report was filed with FERC. On April 28, 2023 the relicensing Final License Application was filed with FERC.

2022: No material changes or compliance issues were identified. The project remains in compliance based on the annual review.  For Condition 1, the project reported no changes. On March 8, 2022 the relicensing initial study report was filed with FERC and a response to comments on the report was filed on June 6, 2020.

2021: There were no reported changes or compliance issues. The project remains in compliance based on the annual review.

2020: There were no reported changes or compliance issues. The project remains in compliance based on the annual review.

2019: There were no reported changes or compliance issues. The project remains in compliance based on the annual review.

2018: There were no reported changes or compliance issues. The project remains in compliance based on the annual review.

2017: Annual reporting for the current Certificate has not yet taken effect.

Certification History

January 1, 2022: The LIHI Certificate term has been extended in accordance with Revision 2.05 of the LIHI 2nd Edition Certification Handbook issued January 1, 2022. Refer to the facility table above for the new term.

January 26, 2018:  The 30-day appeal window closed for the preliminary decision of the Skagit Hydroelectric project on December 30th, 2017 with no appeals to the decision received. The Recertification decision is therefore final.

December 5, 2017: The Skagit Hydroelectric project has received preliminary approval for a new 10-year term of Low Impact Certification. As provided for in the LIHI 2nd Edition Certification Handbook, the Preliminary Decision, along with the Application Reviewer’s report and (if prepared) report of the Executive Director, will be posted on the Institute’s web page for 30-days during which time those who provided comments during the application’s 60-day public comment period can appeal the decision. Any appeal must include specific reasons why the appellant believes the hydropower facility does not meet one or more criteria. Appeal requests can be submitted by email to with “Skagit Hydroelectric Project” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Ave, Suite 2, Lexington, MA 02420. All requests will be posted to the website and the applicant will have an opportunity to respond. Any response will also be posted. Requests must be received by 5 pm EST on December 30, 2017. If no appeal requests are received and the decision becomes final, the new term for the Skagit project will be May 15, 2016 through May 14, 2026.

July 26, 2017: The Low Impact Hydropower Institute received a complete application from the Skagit Hydroelectric project on July 20, 2017. The complete application can be found below. LIHI is seeking public comment on this application.  Specifically, we are interested in knowing whether you think the Skagit project continues to meet the LIHI Low Impact Certification Criteria, as revised in the 2nd Edition Handbook.  Please review the program and criteria in LIHI’s Handbook and then review the Project’s application materials. Comments that are directly tied to specific LIHI criteria (flows, water quality, fish passage, etc.) will be most helpful, but all comments will be considered.  Comments may be submitted to the Institute by e-mail at with “Skagit Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Avenue, Suite 2, Lexington, MA 02420.  Comments must be received at the Institute on or before 5 pm Eastern time on September 26, 2017 to be considered.  All comments will be posted to the web site and the applicant will have an opportunity to respond.  Any response will also be posted.

December 16, 2016: The Skagit Hydroelectric project has been granted an additional extension of the current certificate term. The new expiration date is July 31, 2017. See extension letter for explanation below.

March 18, 2016: The Skagit Hydroelectric project has been granted an extension of the current certificate term. The new expiration date is November 15, 2016. See below for extension letter.

August 28, 2008: The Skagit River Project has been recertified as low impact, continuing to meet LIHI’s eight environmentally rigorous criteria. The project was issued an eight-year certificate, effective May 15, 2008 and expiring May 15, 2016.

July 12, 2008: The Low Impact Hydropower Institute received a comment letter from Aaron Johnson regarding the certification of the Skagit Hydroelectric Project. The letter can be found in the Files section below.

Certification Files

2017 Recertification

2008 Recertification

2003 Certification

Key Documents