The Public Service Commission of Wisconsin voted unanimously Thursday to revoke the completeness determination for American Transmission Co.'s grid expansion serving the Vantage Data Centers campus in Port Washington, sending a project estimated at $1.3 billion to $1.7 billion back to the start of the state approval process.
ATC's application described new high-voltage transmission lines, new substations, and infrastructure upgrades across Ozaukee, Washington, Sheboygan, Calumet, Fond du Lac, and Manitowoc counties, with construction planned to begin in December 2026 and completion targeted for the end of 2027. The buildout exists to deliver power to the hyperscale campus Vantage is developing on the Port Washington lakefront. A completeness determination is the ruling that starts the commission's formal review clock, so revoking it does not reject the lines; it erases the review's starting line.
Behind the reset sits a filing record that kept moving. After the commission ruled the application complete in December 2025, ATC submitted 564 further documents, and a July revision raised the estimated cost to as much as $1.7 billion, according to Urban Milwaukee. Commission staff and ratepayer advocates argued the accumulating changes left regulators and the public without a settled picture of what they were being asked to approve.
Commission Chair Summer Strand said the changes had consequences beyond paperwork. "In addition, and equally troublesome, the magnitude and volume of changes have created a barrier to parties and the public's participation in this proceeding," she said, as reported by Wisconsin Public Radio.
Procedure, not merit, decided the outcome. "We have strict timelines that are feasible only when we have a complete application," Commissioner Marcus Hawkins said. Revoking completeness dissolves the review deadline that had bound the commission to a December decision, and ATC must now file a fresh application in a new proceeding, with the statutory review clock starting over. How long that adds to the schedule is unknown, and neither the commission nor ATC has put a number on it.
Reaction from both companies was measured. ATC said it was "disappointed" and "considering its options," in remarks quoted by Urban Milwaukee. A Vantage spokesperson said: "We will review the Commission's written order when available and evaluate the appropriate next steps." Neither company has published a revised energization date for the campus.
For operators planning capacity behind new transmission, the decision shows an approval clock can restart even after an application has been ruled complete. Any energization date that depends on a line still in front of regulators now carries that reset risk in Wisconsin.
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