Minnesota Power and American Transmission File Application for 345-kV Transmission Line in Itasca and St. Louis Counties, MN

Minnesota Power and American Transmission (ATC) have filed a combined application for a Certificate of Need and Route Permit to build a 345-kV Iron Range-St. Louis County-Arrowhead Transmission Line (ISA) in Itasca and St. Louis counties, Minnesota to strengthen reliability of the regional grid, expand transmission capacity and support growing energy needs.

The application for ISA project was submitted to the Minnesota Public Utilities Commission on January 5. While the construction is expected to begin in late 2027, depending on regulatory approvals, operations are anticipated to initiate before 2032.

The ISA project includes about 67.5 miles of new transmission infrastructure designed to enhance the reliability, efficiency, and transfer capability of the grid. The proposed route runs from Minnesota Power’s Iron Range Substation near Grand Rapids to its St. Louis County Substation near Hermantown, connecting to ATC’s adjacent Arrowhead Substation.

About 92% of the route follows or replaces existing transmission corridors, minimizing environmental and land-use impacts. The project includes three key segments:

• Segment 1: 32.7 miles of new 345 kV line along existing rights-of-way from the Iron Range Substation to the Floodwood area.
•  Segment 2: Replacement of 33.3 miles of 230 kV line with 345 kV double-circuit structures from the Floodwood area to the St. Louis County Substation.
• Segment 3: 1.5 miles of new double-circuit 345 kV line connecting Minnesota Power’s St. Louis County Substation to ATC’s Arrowhead Substation.

The project also includes expansions of ATC’s Arrowhead Substation and Minnesota Power’s St. Louis

County Substation to accommodate new connections and modifications to Minnesota Power’s Iron Range Substation.

The ISA project is part of the MISO Long-Range Transmission Plan Tranche 2.1 Portfolio, approved in 2024. It will:

• Strengthen the regional transmission grid as operating conditions become more variable.
• Increase grid efficiency as energy is transferred from where it is produced to where it is needed.
• Support integration of renewable generation and meet growing demand for clean energy.

“This project is an investment in our communities and in the future as the way energy is produced and used continues to evolve and the operation of the grid becomes more dynamic,” said Josh Skelton, Minnesota Power chief operating officer. “Reliable transmission infrastructure is essential for connecting renewable resources and meeting the region’s growing energy needs.”