On June 25, Western Minnesota Municipal Power Agency (WMMPA), represented through its agent Missouri River Energy Services (MRES), and Otter Tail Power Company received the written order from the Minnesota Public Utilities Commission (MN PUC) approving a Route Permit for the Big Stone South to Alexandria (BSSA) 345-kilovolt transmission line. The utilities will co-own the approximately 96-mile transmission line, strengthening the regional grid while supporting reliable, cost-effective electricity to their customers.

BSSA will connect Otter Tail Power’s existing substation near Big Stone City, South Dakota, with MRES’ existing substation near Alexandria, Minnesota. The companies filed the Route Permit application for the Minnesota portion of the line with the PUC on October 22, 2024.

Strengthening grid reliability and resilience

Otter Tail Power is leading development and construction of the BSSA transmission line. Strengthening the transmission system increases resiliency to extreme weather and helps restore power faster when outages do occur. Reliable power requires responsible, long-range planning — not just maintaining infrastructure but improving it.

“This is a significant milestone as new infrastructure takes years to plan, permit, and build, and we appreciate the Commission’s approval of the Route Permit,” said the companies. “Reliability isn’t built through engineering alone. It’s built through accountability, experience, and a proven track record of keeping people informed, respecting landowners, and working through a transparent, regulated process. This investment helps us continue to meet growing energy needs while maintaining a reliable, resilient energy grid for our customers and the region.”

Otter Tail Power and WMMPA received a Certificate of Need from the PUC in October 2024, confirming the line is necessary and appropriately sized, timed, and designed. In January 2025, the South Dakota Public Utilities Commission approved a Facility Permit for the approximately 3.5-mile portion in South Dakota.

Next steps

Right-of-way agents will work with landowners along the approved route to establish easements and determine structure locations. The companies anticipate construction to begin in 2028 and are targeting an in-service date by the end of 2030.

For more information about BSSA, visit BigStoneSouthToAlexandria.com.

For more information about MRES or WMMPA, please contact MRES Vice President & Chief Strategy

Officer Alex Abplanalp at 605-338-4042 or info@mrenergy.com.