MISO Awarded $1.23 Billion of Iowa 765-Kilovolt Line and Substation Work

MISO selected a consortium of Ameren, GridLiance and Dairyland on Oct. 22 to build the East Adair-Minnesota/Iowa State Line-Arbor Hill-York Avenue project, a roughly $1.23 billion transmission package in southern Iowa. The scope is one new 765-kilovolt line of about 187 miles, one new 345/765-kilovolt substation, and two new 345-kilovolt lines totaling about 22 miles. MISO said the group offered the best overall value on design, execution capability and regulatory experience.

The award sits inside MISO's Long Range Transmission Planning Tranche 2.1 portfolio, which the grid operator's board approved on Dec. 12, 2024: 24 projects, 3,631 miles of line and $21.8 billion across nine Midwest states, with a stated cost-to-benefit ratio of 1.8 to 3.5. MISO put the Iowa package out for competitive bid on Dec. 11, 2025, took proposals through May 26, 2026, and priced the work at $1,226.3 million in 2024 dollars. Ameren Transmission Company of Illinois and NextEra Energy Transmission's GridLiance Heartland will each own 42.5 percent once the project is in service, and Dairyland Power Cooperative holds the remaining 15 percent. The same three were selected earlier this year for the STIW and WIIL projects in Illinois.

The field scope is transmission-voltage construction, part of what Ameren describes as a planned 765-kilovolt backbone. The long line runs north from a new East Adair substation in southern Iowa to the Minnesota state line. One 345-kilovolt line runs south from East Adair to a dead end east of York Avenue; the other runs north to the existing Arbor Hill substation. East Adair is the electrical center of the job, a 345/765-kilovolt yard carrying the structures, bus work, breakers, grounding grid, and protection and control wiring that the voltage class requires.

None of it is imminent. The 345-kilovolt scope carries a June 1, 2032 in-service date and the 765-kilovolt scope a June 1, 2034 date, and the consortium still has to clear state regulatory review, routing and community engagement before crews mobilize. The announcement named no job figures and no contractors below the ownership level.

Iowa licenses electricians through the Electrical Examining Board, housed in the Department of Inspections, Appeals and Licensing, and its Class A journeyman license requires a registered apprenticeship or an approved training plan plus an exam. Much of a utility transmission build sits outside that system. Iowa Code section 103.22 exempts employees of investor-owned utilities, municipal utilities and electric cooperatives from licensure while acting within the scope of their employment, and extends the same treatment to firms under contract to those utilities for work within the utility's public service obligations. The licensed commercial and industrial work arrives later and behind the meter, in whatever load the backbone ends up carrying.

The capital is committed and the in-service dates are set. The buildings that will draw on the line have not been announced.