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We've filed our South Dakota Facility permit.
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Otter Tail Power and Missouri River Energy Services are proposing a new transmission line to connect Otter Tail Power's Big Stone South Substation near Big Stone City in South Dakota to the Alexandria Substation owned by Missouri River Energy Services near Alexandria, Minnesota. We will work closely with landowners, communities, and local officials to identify potential routes and file route permits with appropriate regulatory agencies.

Overview map of transmission line
Explore our interactive map


Otter Tail Power Company, an electric utility owned by Otter Tail Corporation, provides electricity and energy services for approximately 133,000 residential, commercial, and industrial customers across 70,000 square miles in Minnesota, North Dakota, and South Dakota.

Missouri River Energy Services (MRES) is an organization of 61 member municipalities in Iowa, Minnesota, North Dakota, and South Dakota that own and operate their own electric distribution systems. MRES is governed by a 13-member board of directors who are elected by and from the ranks of our member representatives.

Both Otter Tail Power Company and Missouri River Energy Services are members of the Midcontinent Independent System Operator, also referred to as MISO. MISO is a non-profit, member-based regional transmission organization that provides reliable, cost-effective electric systems and operations; dependable and transparent prices; open access to markets; and planning for long-term efficiency.


Long-range transmission planning is necessary to ensure a reliable and efficient regional and interregional transmission system. MISO has identified the BSSA transmission project to support the region's transmission system now and into the future. Otter Tail Power and Missouri River Energy Services are working together with MISO to help keep low-cost energy available and reliable for those who need it. The project will benefit the region by helping to:

  • Ensure electric reliability

  • Increase resiliency to extreme weather events

  • Reduce transmission congestion

  • Increase access to low-cost energy


Developing and constructing a transmission line is a multi-year effort. We'll continue coordinating with landowners, local governments, agencies, and other stakeholders throughout the route development process. The new line is tentatively scheduled to be complete in either 2030 or 2031

Get involved! Click to enlarge

Processes and timing vary from MN to SD. Our project team will refine the timing of these steps to be in compliance with each respective state’s requirements.

Connect with us

Otter Tail Power and Missouri River Energy Services will be engaging with residents, business and property owners, agencies, and other stakeholders.

We still have a ways to go before we finalize a route and begin construction. We are looking forward to your feedback and input as we continue project development.

  • Attend an event

    View upcoming events and past event materials.

    View Events
  • Explore our interactive map

    View our route corridors and add a comment.

    Drop a pin
  • Connect with the team

    Your input is important – we want to hear from you!

    Send us a note

Map & Routing

Learn more about how we route a transmission line and explore our interactive map. Have feedback? Drop a pin to leave us a comment.

See our progress

Library & FAQs

Download project and permitting documents and find answers in our FAQ section.

Learn about the project