Ameren Illinois Constructing New Substation to Bolster Electric Grid in Southern Illinois

New substation will enhance electric service reliability for customers, support economic growth in the area

Key Takeaways:

• Customers in Williamson County and across Southern Illinois will soon benefit from improved reliability thanks to new and upgraded electric substations.
• Substations are critical elements in a reliable, resilient energy grid.
• The new Stilleys substation should be completed and in service by May 2026.

MARION, Ill. (March 3, 2026) - Ameren Illinois is constructing a new substation and making an upgrade to an adjacent substation in Crab Orchard. These projects will enhance energy service reliability, promote access to more sources of energy and improve load capacity for customers in both Williamson County and across southern Illinois.

• Stilleys transmission substation: Construction is underway to meet expected growth in energy demand in southern Illinois. The new substation will handle high-voltage electricity coming into the region and step down the voltage before the electricity is transported to other nearby distribution substations. The substation is designed to support growing economic development in the region.
• Crab Orchard distribution substation: Crews will be upgrading a transformer and other equipment inside the substation. A new power line will also be added from the new Stilleys substation to Crab Orchard substation. These enhancements add flexibility and resiliency to meet future customer demand. The added capacity is similar to expanding a two-lane highway to a six-lane major highway.

"Substations do not get a lot of fanfare, but they are critical elements in a reliable, resilient energy grid," said Ty Lindhorst, director of south region electric operations for Ameren Illinois. "With these enhancements, Ameren Illinois is taking proactive steps to prepare for the future needs of our electric customers. We're excited to bring these benefits to our customers in southern Illinois."

The new Stilleys substation should be completed and in service by May 2026.

About Ameren Illinois
Ameren Illinois delivers energy to 1.2 million electric and more than 800,000 natural gas customers throughout central and southern Illinois. Our service territory covers more than 1,200 communities and 43,700 square miles and our mission is to power the quality of life. For more information, visit AmerenIllinois.com. Follow us at @AmerenIllinois or Facebook.com/AmerenIllinois.