Tyee Lake Hydroelectric Project 

 

The Tyee Lake Hydroelectric Project (Project) is located on Tyee Lake and at the head of Bradfield Canal, approximately 40 miles southeast of the community of Wrangell and 60 miles northeast of Ketchikan, Alaska. The Project occupies mostly state lands surrounded by the Tongass National Forest. 

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Power is transmitted from the powerhouse along transmission lines that run north to Wrangell and Petersburg, and south to Ketchikan. The Project provides power to Wrangell Municipal Light and Power, Petersburg Municipal Power and Light, and Ketchikan Public Utilities. The Tyee Lake Project currently contributes approximately 105,800 MWh of electricity annually to the region. 

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The Tyee Lake Project features consist of a spillway weir, lake tap intake, power tunnel, penstock, powerhouse, switchyard, and appurtenant structures. The Tyee Lake Project does not include a dam but diverts water to the powerhouse from the naturally impounded Tyee Lake through a lake tap intake. The reservoir is managed between normal pool elevation 1,396 feet mean lower low water (mllw) and minimum operating pool elevation 1,250 feet mllw. Water is conveyed to the powerhouse, located at tidewater near Bradfield Canal, through an intake from the lake into a drop shaft, through an 8,300-foot-long unlined power tunnel and a 1,350-foot-long steel penstock, which currently houses two Pelton-type horizontal-axis generating turbine units. 

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SEAPA intends to install a third turbine unit in the empty bay of the powerhouse in fall of 2027, increasing the installed capacity of the Project by 50 percent, from 22.5 MW to 33.75 MW.