Big Stone South to Alexandria
Transmission LineThis project will help enhnace the transmission grid and continue to provide reliable, cost-effective electricity to customers across the region.
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Written comments will be accepted through October 20, 2025, by 4:30 p.m. Learn more here!
Overview
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 have worked closely with landowners, communities, and local officials to identify potential routes and file route permits with appropriate regulatory agencies.
Explore our interactive map
Explore our interactive map
Benefits
Long-range transmission planning is necessary for 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:
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Enhance electric reliability
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Increase resiliency to extreme weather events
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Reduce transmission congestion
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Increase access to low-cost energy
Schedule
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 by the end of 2030.
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- Minnesota Route Permit Application filed - 2024
- Survey activities, right-of-entry and right-of-way coordination - 2024 to 2027
- Anticipated Minnesota Public Utilities Commission decision on Route Permit - 2026
- Prepare contractors and materials for construction - 2026 to 2027
- Construction - 2028 to 2030
- Energize line - 2030
- Restoration - 2030 to 2031
Processes and timing vary from MN to SD. The South Dakota Public Utilities Commission approved our Facility Permit in January 2025. 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 continue engaging with residents, business and property owners, agencies, and other stakeholders.
The MN PUC public hearings are an important part of the regulatory process, and an opportunity to hear from you directly on the route options being considered. We look forward to your feedback and input as we continue to develop the project.
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Attend an event
View upcoming events and past event materials.
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Explore our interactive map
View our Proposed Route Options.
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Map & Routing
Learn more about how we route a transmission line and explore our interactive map.
See our progressLibrary & FAQs
Download project and permitting documents and find answers in our FAQ section.
Learn about the project
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.