IMEA Among Consortium Chosen to Deliver Major Grid-Bolstering Project
Date Posted: 2026-05-22
The Midcontinent Independent System Operator (MISO), the regional transmission organization that serves central and southern Illinois, has selected the Illinois Municipal Electric Agency (IMEA); Ameren Transmission Company of Illinois (ATXI); GridLiance Heartland, LLC; and Dairyland Power Cooperative to develop, build, operate and maintain two major transmission projects across Illinois.
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.
IMEA CEO and President Doug Brown states, “Increasing transmission capacity on the grid is critical to improving resiliency, integrating new resources and supporting long-term economic developments.” He added that the Illinois Municipal Electric Agency is proud to be a partner on these projects and sees the investment as critical to offset transmission costs into the future.
Ameren Transmission Company of Illinois (ATXI), a subsidiary of Ameren Corporation (NYSE: AEE) and GridLiance Heartland, LLC, a subsidiary of NextEra Energy Transmission, LLC will each own 43% of each transmission project. Dairyland Power Cooperative will own 11% and IMEA will own 3%. 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 entire project includes two specific facilities, STIW and WIIL.
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 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.
These projects are expected to be operational in 2034.