A century ago, engineers scoured the upper Skagit River searching for bedrock to site three dams.
"There is a great scarcity of electric current in Western Washington," Seattle City Light boss J.D. Ross said in a 1921 pamphlet pushing his plan for dams on the Skagit to bring cheap power to the growing city.
The Skagit made good on Ross' promise of providing plentiful, low-cost power for Seattle. But it came at a high price for the Upper Skagit Indian Tribe.
"Hydropower in the upper Skagit has provided benefits to the city of Seattle for over a century now and the disproportionate lack of reinvestment in the Skagit must be seriously looked at, because our precious river is in dire need of help," Scott Schuyler, the tribe's natural resources director, said in an article for the Northwest Treaty Tribes.
Seattle City Light filed its pre-application document to relicense its Skagit River hydroelectric project with FERC on April 30 [P-553].
The tribe believes hydropower's negative effects extend into Puget Sound, Schuyler said. "The Skagit tribes rely on a healthy, productive Skagit to sustain our fishing culture, and today we are faced with a complete fishery disaster."
The project's priorities "are, in descending order of importance: flood control, downstream fish protection, recreation, and power production," the preapplication document states.
The Skagit River Hydroelectric Project's license was renewed in 1995 following a major settlement to protect fisheries [EL78-36-000]. The utility spent tens of millions of dollars on environmental and cultural mitigation.
The river is the only one in the Puget Sound region that is home to all five native salmonid species. It also provides habitat for three fish species—Chinook salmon, steelhead and bull trout—listed as threatened by the federal government.
Seattle already has had talks with 21 entities, including federal and state agencies, tribes, and nongovernmental organizations, to develop initial study plans. The preapplication proposes 24 studies. SCL has to file a study plan by Oct. 12, and the initial study report is slated to come out in early 2022.
The hydro project's license expires April 30, 2025. The city must file its relicensing application by April 30, 2023.
The project's three dams—Gorge, Diablo and Ross—operate as one generation resource that provides about 20 percent of Seattle City Light's load requirements, according to the document.
Combined, the dams have 650 MW installed capacity. In March, SCL filed revised documents and asked FERC to increase the authorized installed capacity to 805 MW; no decision has been made.
Gorge has 173 MW capacity and 52 percent annual capacity factor; Diablo has 182 MW capacity and 48 percent annual capacity factor; and Ross has 450 MW capacity and 13.4 percent annual capacity factor, according to the document.
Gorge's plant capability is 207 MW, but generating capacity is capped at 173 MW due to constraints exacerbating head loss.
Two 230-kV lines connect the Skagit project, which is located in Whatcom, Skagit and Snohomish counties. From 2014 through 2018, the project's average annual energy production was more than 2.5 million MWh.
The current project license requires Seattle City Light to use Ross Lake for flood control. The reservoir must provide 60,000 acre-feet in flood storage by Nov. 15 and 120,000 acre-feet by Dec. 1 through March 15. Flows on the Skagit can be capped at 5,000 cubic-feet per second based on National Weather Service forecasts for river level downstream.
Once past flood control mandates, the license requires SCL to fill Ross Lake as soon as possible after April 15, with full pool by July 31, for recreational uses.