NorthWestern Energy proposes to construct, operate and maintain the Mountain States Transmission Intertie (MSTI), a 500 kilovolt (kV) 1,500 megawatt transmission line, delivering electricity from the state of Montana to customers in the Western United States. The intent of the MSTI project is to address the need for new electric transmission service from generating sources to customers and to help bolster the western power grid.
MSTI will begin at the new Townsend Substation, which will be constructed about five miles south of Townsend, Montana. The line is being designed to proceed south into southeastern Idaho connecting to Idaho Power Company’s existing Midpoint Substation, 10 miles north of Jerome, Idaho.
Energy carried on the MSTI line will be generated primarily from renewable electric generating facilities located in Montana. This electricity will be sold by those generators to customers to help fulfill new energy demand and Renewable Portfolio Standards established by western states. The MSTI line is a new conduit for delivering this clean electricity between its collection point at Townsend to those needing this energy. NorthWestern Energy will operate and maintain the MSTI line but is not engaged in generating the electricity on the MSTI line. The Midpoint Substation is a primary electric distribution point in the western United States.
Currently, an Environmental Impact Statement (EIS) is being conducted in Montana and Idaho to determine a route for MSTI project. Work on the EIS began in July 2008 when NorthWestern submitted to the Bureau of Land Management (BLM) and the Montana Department of Environmental Quality (MDEQ) its application for siting the MSTI project. In this website you will find additional information about the siting process. The Draft EIS is scheduled for release soon from the BLM and MDEQ. That will initiate another series of public meetings in the areas where the line is sited. Please return to the MSTI website often for continued updates. If you have additional question or concerns please contact the MSTI team at NorthWestern Energy and we will assist you to find the right information about the MSTI project.
Cost to Build MSTI $1 Billion
Estimated Route Miles 430 miles depending on final route determination
Capacity 1,500 megawatts
Tower Height 125 to 140 feet depending on terrain
Tower Description Guide V towers or Monopoles (Single circuit)
Width of Right of Way 220 feet
Estimated Tax Benefits Annually $15 to 37 million in Montana - $2,282,000 in Idaho