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Colstrip Transmission System Facts

The Colstrip Transmission System was built in the early 1980s to move power from the Colstrip generating facilities to transmission systems in western Montana. The Colstrip system is made of two 500 kilovolt segments. The first runs from Colstrip to Broadview. The second runs from Broadview to Townsend. Colstrip power moves across the Bonneville Power Administration’s (BPA’s) transmission system west of Townsend before reaching local utility customers and BPA’s main grid.


Colstrip Units 1 and 2 were retired in January 2020. One frequently asked question is: what is happening to the Colstrip Transmission System and the Montana Intertie now that Units 1 & 2 are offline.


The answer is that additional transmission capacity may be available on the Colstrip line, but access to that capacity can only be obtained by following the Federal Energy Regulatory Commission (FERC) rules which are referenced in the fact sheet below. Additionally, access would need to meet requirements under the Montana Intertie Agreement. The following video offers facts to help explain.

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