On June 25, Otter Tail Power Company and Western Minnesota Municipal Power Agency (WMMPA), represented through its agent Missouri River Energy Services (MRES), received the written order from the Minnesota Public Utilities Commission (MPUC) 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 and supporting reliable, cost-effective electricity.
BSSA will connect Otter Tail Power’s existing substation near Big Stone City, South Dakota, with MRES’s existing substation near Alexandria, Minnesota. The companies filed the Route Permit application for the Minnesota portion of the line with the MPUC 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 MPUC 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.
This news release is available at otpco.com/newsroom.
About Otter Tail Power Company
Otter Tail Power Company, a subsidiary of investor-owned Otter Tail Corporation (Nasdaq Global Select Market: OTTR), is headquartered in Fergus Falls, Minnesota. The company generates, transmits, and distributes electricity to approximately 134,200 customers in 422 communities across 70,000 square miles of Minnesota, North Dakota, and South Dakota.
To learn more about Otter Tail Power, visit otpco.com. To learn more about Otter Tail Corporation, visit ottertail.com.
About Missouri River Energy Services
Missouri River Energy Services (MRES) is a South Dakota-based not-for-profit joint-action agency that provides wholesale electricity and energy-related services to 61 member municipalities in Iowa, Minnesota, North Dakota, and South Dakota. MRES is committed to enhancing the value of member utilities to their communities by supplying reliable, cost-effective, long-term energy and energy services in a fiscally responsible and environmentally sensitive manner.
To learn more about MRES, visit mrenergy.com.
About Western Minnesota Municipal Power Agency
Western Minnesota Municipal Power Agency (WMMPA) was incorporated on June 16, 1976, as a municipal corporation and political subdivision of Minnesota. WMMPA has a formal relationship with MRES through which WMMPA finances the construction and acquisition of the generation and transmission facilities for MRES members. MRES provides the administrative services to manage WMMPA’s portfolios. WMMPA’s membership includes most of the Minnesota members of MRES.
