* 8/7/25 - Green Light for Ameren Illinois $1.6B, 380-Mile Transmission Build .............................
Buzz Sawyer
380 miles of high voltage lines will benefit entire state, increase access to energy sources
PEORIA, Ill., Aug. 5, 2025
Green Light for Ameren Illinois $1.6B, 380-Mile Transmission Build
Certificate clears construction start later this year on new 345-kV lines and three substations across the state
Ameren Illinois’ Central Illinois Grid Transformation Program will add 380 miles of 345-kV lines and three new substations, with upgrades to five others across 13 counties. Approval clears construction to start later this year, with the line energized in phases through 2029.
August 7, 2025
Ameren Illinois announced Aug. 5 that the Illinois Commerce Commission granted a certificate of public convenience and necessity for its Central Illinois Grid Transformation Program. The approval clears the way for construction later this year on 380 miles of 345-kilovolt transmission lines, three new substations and upgrades to five existing substations across 13 counties as part of a $1.6-billion upgrade.
The project stems from the Midcontinent Independent System Operator (MISO) 2024 Long-Range Transmission Plan Tranche, which identified critical bottlenecks in the Midwest grid.
The new lines will be co-located alongside existing Ameren corridors across 13 central Illinois counties—from the Mississippi River at Quincy through the Peoria metro area to Tazewell County.
Eight substations—three new facilities at Camp Point, Kenney and Piper City and five rebuilt or expanded stations in Brown County, Pontiac, Gibson City, Iroquois County and Peoria—will be tied into the network, with upgraded communications and supervisory control and data acquisition systems to monitor and control equipment remotely.
“At a time when the Midwest faces a persistent shortage of the electricity needed to meet rising demand, this vital project will provide energy access and certainty for businesses and residential growth,” said Shawn Schukar, chairman and president of Ameren Transmission Co. of Illinois, in a company release.
Ameren filed its joint petition in January 2024 (ICC Docket 24-0088), submitting detailed routing maps, a preliminary cost-benefit analysis and wetland assessment summaries. Commission staff issued 25 data requests, probing right-of-way acquisition plans, load-flow modeling, environmental mitigations and coordination with third-party infrastructure owners.
Map courtesy of Ameren Illinois
Public hearings in Springfield in May 2024 drew testimony from private-landowner groups and individual witnesses who suggested alignment tweaks. However, commission staff, along with Ameren engineers, said such deviations would raise costs by 2%–4% or require new substation work, and approved the original alignment as “necessary to maintain reliability and support future load growth.”
Several commenters raised land‐use and health concerns: James Williams, whose Iroquois County farm borders a 138-kV line, urged the commission to “use existing rights-of-way” rather than take new farmland. Matthew Hadsall of Peoria County warned, “My greatest concern as a father of seven children is their health living close to high-voltage power lines,” and asked for a quarter-mile residential setback.
Ameren responded that “existing environmental controls and species-protection measures meet all state and federal requirements” and that package deviations could increase costs or complicate substation design.
Pooled analyses have found that children in homes with average extremely low-frequency magnetic fields above 0.3–0.4 µT—levels common within about 100 m of major transmission lines—face roughly twice the risk of childhood leukemia, and the International Agency for Research on Cancer classifies these fields as possibly carcinogenic to humans (Group 2B).
Still, leading health agencies maintain that routine residential exposures pose little substantiated risk: the World Health Organization reports “no substantive health issues” at environmental field levels, and the U.S. Environmental Protection Agency notes that studies have not consistently demonstrated adverse effects at typical exposure levels.
Read More:
Illinois Commerce Commission Docket 24-0088 | Central Illinois Grid Transformation Program
Detailed plans accompanying the petition that ENR reviewed show that new and upgraded circuits will cross or parallel 42 railroad segments, 16 major pipeline corridors and 78 existing high-voltage circuits within half-mile buffers, requiring coordination with more than 100 infrastructure owners. Notice was sent under ICC Rule 305.60 to all affected railroads and utilities.
In its July 2 final order, the commission imposed two conditions: Ameren must file quarterly updates on right-of-way negotiations, and submit a final wetland-mitigation plan at least 90 days before beginning work in any county.
The utility also must secure local zoning and building permits, complete endangered species and cultural-resource reviews, and finalize MISO interconnection studies before mobilizing in mid-2026.
Project management will be handled by an internal Ameren services team, employing union contractors and local subcontractors for line work, substation assembly, surveying and road monitoring. Easement negotiations are led by Emerald Energy & Exploration, Volkert and Contract Land Services.
Cost allocation splits roughly $1.29 billion in transmission-plant costs into $1.225 billion borne by Ameren Transmission Co. and $66 million by Ameren Illinois, with 91% charged to the broader MISO Midwest sub-region and 8.87% to downstate customers.
“When we increase system capacity, everyone wins,” Thomas Pauk, project manager for the program, stated in the release. “Opening new energy pathways promotes lower costs in the future and helps keep customer rates affordable.”
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Key milestones include the first right-of-way status report due Oct. 1; preliminary mobilization in November; Adams County wetland-mitigation plan due Dec. 3; main-line stringing and tower erection mid-2026; and phased energization through late 2029.
ENR contacted Ameren for additional details on awarded contractors, substation technical specifications, performance targets and workforce projections. Brad Brown, a spokesman for Ameren, said the company could not provide those particulars before press time but added, “I will clarify the $1.6 billion cost estimation is inclusive of a segment that goes into Missouri; the Illinois Commere Commission cost estimate is for just under $1.3 billion.”