PSC deals major blow to transmission project supporting Port Washington data center

State utility regulators have dealt a major setback to a more than $1 billion transmission project that would serve the hyperscale data center campus being built in Port Washington.

The Public Service Commission of Wisconsin unanimously voted on Thursday to revoke a “completeness” determination for American Transmission Co.’s application to build a major distribution and interconnection project.

That means American Transmission Co., or ATC, will have to submit a new application for the project. Regulators said the application had seen such extensive revisions that it was difficult for officials and the public to adequately review.

PSC chair Summer Strand said ATC filed or refiled 564 application documents after receiving a completeness determination late last year. She said the “magnitude and volume of changes to the application” resulted in what she called a “moving-target application.”

That “created a situation where our staff cannot uphold their responsibilities, and this has created an impediment to their preparation of offered evidence,” Strand said. “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.”

It’s a rare move for the utility regulator.

American Transmission Co. and a ratepayer watchdog both say it’s the first time they’ve seen the PSC revoke a completeness determination in recent decades, if ever.

While the decision isn’t a denial of the project itself, ATC needs to file a new application in a new proceeding with the agency, essentially restarting the process from the beginning.

“This is not a decision made lightly,” Strand said. “I recognize the impacts this decision will have on construction timelines and in-service dates for the project. This is an unfortunate outcome.”

In PSC filings, ATC had said the project is needed to provide electric service to a new data center under construction.

A spokesperson for Vantage Data Centers, one of the developers behind the Port Washington data center campus, said in a statement that the company respects the commission’s role, but it is disappointed in the decision.

The spokesperson said Vantage will work with utilities, officials and the public to pursue “responsible development” of the transmission infrastructure needed to support the project.

“We will review the Commission’s written order when available and evaluate the appropriate next steps,” the statement read.

The cost of the Ozaukee County Distribution project was estimated to be between $1.3 billion and $1.7 billion, according to a revised application filed in July. It would have included new substations, new high-voltage transmission lines and upgrades to existing infrastructure.

The project’s infrastructure would have spanned Ozaukee, Washington, Sheboygan, Calumet, Fond du Lac and Manitowoc counties. American Transmission Co. hoped to begin construction in December and complete the buildout by the end of 2027.

The PSC previously gave the utility’s application a “completeness” determination in December 2025. But since then, the agency said ATC filed “a large number” of substantial changes to its application.

Last month, the agency’s administrative law judge raised concerns about missing and changing information in the application. 

The commission’s vote closed the current case and eliminated the December 2026 deadline for regulators to rule on that application.

In a statement, an ATC spokesperson said the company was disappointed in the PSC’s decision and was “considering its options.”

“We recognize there is significant public interest in this project and appreciate the time people have taken to participate in the PSCW process and share their perspectives,” the statement read.

American Transmission Co. argued against revoking the completeness determination in filings with the PSC, saying it would be a first for the utility regulator.

“In its entire history, the Commission has never revoked a determination that a CPCN application is complete,” attorneys for ATC wrote in a regulatory filing. “It should not do so for the first time here.”

But the project faced a lot of pushback from locals and anti-data center activists. That includes comedian Charlie Berens, who submitted comments to the PSC critical of the utility’s proposal.

“It’s no longer clear to the public or public officials what their actual plans are,” he wrote. “Allowing ATC’s half-assed attempt at transparency would set a terrible precedent for Wisconsin.”

All three PSC commissioners were critical of the volume of changes to ATC’s proposal.

PSC Commissioner Marcus Hawkins said he believed a new application was the only way to give the public and intervening parties “the process that they deserve.”

“We have strict timelines that are feasible only when we have a complete application,” he said. “Given that it sounds like we are finding that we do not have that today, this seems to be the only option that allows our requirements to play out.”