Ketchikan Public Utilities is a member of SEAPA (Southeast Alaska Power Agency), along with the Utilities of Wrangell and Petersburg, who both get their hydropower primarily from Tyee Lake. Ketchikan and the Northern communities are linked by large transmission lines, called the intertie. SEAPA and Ketchikan have a Power Sales Agreement (PSA), which requires that Ketchikan purchase SEAPA's power for any requirement beyond what it can generate from its grandfathered projects Ketchikan Lakes and Silvis/Beaver Falls.
Hydropower is Ketchikan's primary source of power generation. Ketchikan gets its hydropower from several projects: Ketchikan Lakes, Silvis Lakes, Beaver Falls, Whitman Lake, along with SEAPA's Swan and Tyee Lake projects when available. When lake levels are low, supplemental diesel power may be required. KPU has several very large diesel generators at Bailey power plant and two smaller units at North Point Higgins. These are only used as backup generators, not for primary power generation unless lake levels are too low, and power is not available from SEAPA.
Ordinarily, Ketchikan receives enough precipitation through rain and snow to supply about 50% of its firm power requirements with its own hydropower. The additional 50% comes from the power sales agreement with SEAPA. SEAPA owns both Swan Lake and Tyee Lake, and only SEAPA, under the power sales agreement, could develop the next energy production facility in their network.
There is a permit for a Mahoney Lake hydro-facility that is owned by the village of Saxman. They do not have the capital to build the facility, and they cannot obtain a loan to build the facility unless SEAPA and KPU would agree to purchase power from them every year, on a regular basis. SEAPA ordinarily has enough power to support all three member communities without additional hydro-power and therefore would not agree to bring power from Mahoney Lake into the mix until the existing Swan and Tyee projects are fully utilized. Accruing multimillion dollar bond-debt to construct a facility that would be used only infrequently makes the proposal to develop Mahoney economically untenable.
Green - Reservoir levels are high or rising steadily - Diesel supplementation is unlikely.
normal - Diesel supplementation may be necessary at a later date.
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Upper Silvis Lake
Lower Silvis Lake