MISO selects consortium of Ameren, GridLiance, Dairyland, Illinois Municipal Electric Agency to deliver major grid-bolstering projects in Illinois

ST. LOUIS, May 19, 2026 /PRNewswire/ -- The Midcontinent Independent System Operator (MISO) has selected a consortium of Ameren Transmission Company of Illinois (ATXI), a subsidiary of Ameren Corporation (NYSE: AEE); GridLiance Heartland, LLC, a subsidiary of NextEra Energy Transmission, LLC; Dairyland Power Cooperative; and the Illinois Municipal Electric Agency (IMEA) to develop, build, operate and maintain two major transmission projects. ATXI and GridLiance will lead the development of these projects, while Dairyland and IMEA will own a portion of both projects when they are placed in service.

The Sub T – Iowa/Illinois State Line – Woodford County (STIW) and Woodford County – Illinois/Indiana State Line (WIIL) projects are the foundation of a new 765-kilovolt (kV) backbone that will deliver safe, reliable and cost-competitive energy to serve Midwest communities for decades to come. 

The STIW project includes the construction of two new 765-kV transmission lines spanning approximately 149 miles. One 765-kV line will run from the Woodford County Substation west to the Iowa/Illinois state line, and the other 765-kV line will continue west from the Iowa/Illinois state line to the Sub T Substation in Iowa. The STIW project has a MISO estimated cost of $940 million.

The WIIL project includes the construction of two new 765-kV transmission lines that span a total of 88 miles and the construction of a new 765/345-kV substation. One 765-kV line will run east from the existing Woodford County Substation in central Illinois to the Illinois/Indiana state line. The other 765-kV line will run northeast from the Woodford County Substation for approximately 1.5 miles toward the existing Collins Substation before interconnecting with a separate 765-kV line segment. The WIIL project has a MISO estimated cost of $718 million.

ATXI, GridLiance, Dairyland and IMEA will have ownership stakes in both projects of 43%, 43%, 11% and 3%, respectively.

"We are committed to delivering infrastructure that strengthens the grid and creates value for customers both now and over the long term," said Shawn Schukar, chairman and president of ATXI. "The collaboration between ATXI, GridLiance, Dairyland and IMEA enables us to work with our local communities, regulators and local contractors to effectively and efficiently build this valuable transmission system expansion while supporting the growth in our region."

"These projects are critical to building a stronger, more resilient transmission backbone for the Midwest," said Matt Valle, president of NextEra Energy Transmission, LLC. "We're proud to work with ATXI, Dairyland and IMEA to deliver needed energy infrastructure to enhance reliability, support growing energy needs and benefit communities for decades to come."

"As a critical services provider, Dairyland is pleased to be part of a consortium that will help ensure the reliability and flexibility of the transmission system in the Upper Midwest for current and future generations," said Ben Porath, Dairyland executive vice president and chief operating officer.

"Increasing transmission capacity on the grid is critical to improving resiliency, integrating new resources and supporting long‑term economic developments," said IMEA CEO and President Doug Brown. "The Illinois Municipal Electric Agency is proud to be a partner on these projects."

Both WIIL and STIW are competitive projects in MISO's Long Range Transmission Planning Tranche 2.1 Portfolio, which was originally approved in December 2024. Both projects have expected in-service dates of 2034, following the regulatory review process and thorough stakeholder and community engagement.

About Ameren Corporation
St. Louis-based Ameren Corporation powers the quality of life for 2.5 million electric customers and more than 900,000 natural gas customers in a 64,000-square-mile area through its Ameren Missouri and Ameren Illinois rate-regulated utility subsidiaries. Ameren Illinois provides electric transmission and distribution services and natural gas distribution services. Ameren Missouri provides electric generation, transmission and distribution services, as well as natural gas distribution services. Ameren Transmission Company of Illinois develops, owns and operates rate-regulated regional electric transmission projects in the Midcontinent Independent System Operator, Inc. For more information, visit Ameren.com, or follow us at @AmerenCorp, Facebook.com/AmerenCorp, or LinkedIn.com/company/Ameren.

About NextEra Energy Transmission
NextEra Energy Transmission, LLC is North America's leading competitive transmission company. With more than 3,200 miles of transmission lines in operation and development in 19 states and Canada, the company is strengthening and modernizing the electric grid to meet the country's growing energy needs. NextEra Energy Transmission owns, develops, finances, constructs, operates and maintains transmission assets across the continent. The company operates through its regional subsidiaries to integrate diverse energy sources. NextEra Energy Transmission, LLC is a subsidiary of Juno Beach, Florida-based NextEra Energy, Inc. For more information, visit www.NextEraEnergyTransmission.com. 

About Dairyland Power Cooperative
Headquartered in La Crosse, Wis., Dairyland provides the wholesale electrical requirements for 24 distribution cooperatives and 27 municipal utilities. These cooperatives and municipals, in turn, supply the energy needs of over 800,000 people in a four-state service area. Dairyland delivers electricity via 3,708 miles of transmission lines and 400 distribution substations located throughout the system's 44,500 square mile service area. Visit www.DairylandPower.com.

About Illinois Municipal Electric Agency
The Illinois Municipal Electric Agency (IMEA) is a not-for-profit unit of local government created in 1984 that provides wholesale power supply and related services to municipal electric systems across Illinois. IMEA is currently comprised of 32 municipal electric systems, each of which owns and operates its own electric distribution system, with some also operating local power generation plants. Through collective action, IMEA helps its member communities secure affordable, reliable and sustainable energy while preserving local control over rates, services and utility-related solutions. For more information, visit www.imea.org.

SOURCE Ameren Corporation