Southern Illinois Reliability Project

Ameren Illinois has completed and energized the Southern Illinois Reliability Project. The 140 miles of rebuilt, 345 kV line is providing greater energy reliability, more access to renewable energy and has increased transmission capacity across seven counties in southern Illinois.


The Southern Illinois Reliability Project reconstructed the existing 230-kV transmission line from Cahokia to Joppa, originally built in the 1950s. Customers in St. Clair, Washington, Perry, Franklin, Williamson, Johnson and Massac counties are now benefiting from the infrastructure upgrades.

The upgraded transmission line is improving system reliability while opening pathways for clean energy to be distributed to the region. It is also increasing transmission capacity to meet the area's growth needs.

Crews completed the Southern Illinois Reliability Project in December 2023. Land restoration efforts will continue into the spring of 2024.

Southern Illinois Reliability Project Community Benefits

  • Rebuilding aging infrastructure and enhancing our energy system to improve reliability
  • Promoting access to renewable energy resources like solar
  • Increasing transmission capacity

Contact Us

Phone: 618.808.3093


Southern Illinois Reliability Project
c/o Volkert
1500 Eastport Plaza Drive, Suite 200
Collinsville, IL 62034

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