Data Center Census

Port Washington, Ozaukee County, WI

Port Washington (Lighthouse) Data Center Campus

Also known as Lighthouse

Under constructionGroundbreaking Dec. 2025; ATC refiled its grid-connection application Sept. 14, 2026 after regulators ordered a restart
  1. Rumored
  2. Proposed
  3. Approved
  4. Under construction
  5. Operating

A $15 billion, four-building data center campus on 672 acres on the north side of Port Washington, Wisconsin, developed by Vantage Data Centers for OpenAI and Oracle's Stargate effort. Vantage lists 902 MW of critical IT load; local reporting cites 1.3 GW initially and up to 3.5 GW in later phases. Construction began in December 2025; in August 2026 state regulators sent ATC's $1.3 billion-plus transmission project back for a new application, which ATC refiled in September 2026, and Oracle is litigating PSC credit/collateral rules.

Key facts

Size & schedule

Planned capacity1.3 GW [2]
1.3 GW initially, up to 3.5 GW in later phases, per BizTimes
IT load902 MW [4]
Critical IT load per Vantage
Site size672 acres [1]
DNR says Vantage owns 1,644 acres in the area
Floor area2.5 million sq ft [4]
Buildings4 [4]
Stated investment$15 billion [2]
Permanent jobs (promised)1,000 [2]
300 Vantage employees plus 700 tenant employees after completion
Construction jobs4,000 [5]
Peak of 4,000+ skilled construction workers over a three-year build, per Vantage/Building Trades release
Target completion2028 (Vantage); We Energies CEO said launch on track for late 2027 [4]

Power

UtilityWe Energies (transmission by American Transmission Co.) [7]
Power supplyDeveloper says 70% of campus power from solar, wind and battery storage, with renewable purchases matching the rest [4]
Backup generators45 diesel-fired emergency generators [1]
Source excerpt
“On June 12, 2026, the DNR issued a minor source air pollution control construction permit (25-MIN-094) and initial operation permit (24618528A-F01) for 45 diesel-fired emergency generators.”
Air permitWDNR minor source construction permit 25-MIN-094 and initial operation permit 24618528A-F01 issued June 12, 2026 for 45 diesel-fired emergency generators [1]
Source excerpt
“On June 12, 2026, the DNR issued a minor source air pollution control construction permit (25-MIN-094) and initial operation permit (24618528A-F01) for 45 diesel-fired emergency generators.”
Utility commission casePSCW docket 137-CE-229 (ATC Ozaukee County Distribution Interconnection Project) [9]
ATC grid-connection project serving the campus
Source excerpt
“The project is subject to approval by the PSCW. Additional information about the proposed project can be found on the PSCW website under docket number 137-CE-229.”
Utility commission casePSCW docket 6630-TE-113 (We Energies very large customer tariff; decision of May 21, 2026, challenged by Oracle) [10]
Source excerpt
“Oracle America Cloud Services LLC ("Oracle" or "Petitioner") petitions for review of the Public Service Commission of Wisconsin's ("Commission" or "Respondent") May 21, 2026 decision in Commission Docket No. 6630-TE-113.”

Water

Water use10,000 gal/day [2]
Up to 10,000 gallons daily for cooling, per BizTimes
CoolingAir-cooled and liquid-to-liquid systems with closed-loop chilled water (developer says WUE near zero) [4]

Money & incentives

Tax incentivesTax Incremental District No. 5: Vantage pays upfront for about $175 million in infrastructure (water and sewer main extensions, road improvements), reimbursed through the TID, which stays open up to 20 years or until Vantage is repaid [11]
Source excerpt
“Vantage will pay upfront for an estimated $175 million in infrastructure improvements for the project — including water and sewer main extensions and road improvements — through the newly created TID.”

Local decisions & site

Deciding votePort Washington Common Council unanimously approved resolution creating Tax Incremental District No. 5 for the campus (November 2025) [11]
Source excerpt
“The Port Washington Common Council unanimously approved a resolution Tuesday to create Tax Incremental District, or TID, No. 5 for the data center campus.”

Figures are as stated by the cited source. Where sources disagree, each figure is shown.

Lawsuits

Oracle America Cloud Services LLC v. Public Service Commission of Wisconsinpending [10]
Oracle seeks judicial review of the PSC's May 21, 2026 decision in docket 6630-TE-113 modifying We Energies' proposed financial support requirements for very large customers, citing its Lighthouse campus in Port Washington.
Ozaukee County Circuit Court (Case No. 2026CV000256) · filed Jun 19, 2026
Source excerpt
“In partnership with Vantage Data Centers Wisco Acquisition Company LLC ("Vantage") and OpenAI, Oracle is developing the Lighthouse Data Center Campus in Port Washington, Ozaukee County, Wisconsin, a nearly one-gigawatt data center campus that will span approximately 672 acres and feature four large data center buildings”

Timeline

  1. Common Council approves Final Development Agreement with Vantage Data Centers [3]

  2. Vantage and Wisconsin Building Trades Council announce labor partnership for $15B+ campus [5]

  3. Port Washington Common Council unanimously approves creation of Tax Incremental District No. 5 for the data center campus [11]

  4. DNR issues WEPA compliance determination, wetland exemptions and stormwater coverage [1]

  5. Groundbreaking held as construction begins [2]

  6. Port Washington voters approve a referendum requiring voter approval of future large TIDs; it does not affect the TID already approved for the data center [12]

  7. DNR public hearing on air permit (comment period Mar. 3-Apr. 14) [1]

  8. DNR issues air construction and operation permits for 45 diesel emergency generators [1]

  9. Oracle files petition in Ozaukee County Circuit Court seeking review of the PSC's data center tariff decision [10]

  10. Oracle credit rating falls to BBB-; PSC rejects We Energies request to reconsider collateral rules; Oracle challenges rules in Ozaukee County Circuit Court [7]

  11. PSC requires ATC to restart its application for the $1.3B+ transmission line and five substations serving the campus [6]

  12. ATC refiles its application for the grid upgrades serving the campus, dropping a Trenton-Saukville line segment and restarting the PSC's six-month review [8]

Issues raised

  • Oracle is suing over PSC rules requiring AAA- credit or collateral from data center customers, which could cost it over $100 million a year [7]
  • ATC grid-connection project delayed after PSC reset its 180-day review; December 2027 deadline described as in question [6]

Sources

  1. Port Washington Data Center Proposal
    Wisconsin Department of Natural Resources · Jun 12, 2026 · government
  2. Groundbreaking held as construction begins on $15 billion Port Washington data center
    BizTimes Milwaukee · Dec 17, 2025 · news
  3. Data Center Project
    City of Port Washington · 2025 · government
  4. Port Washington (Lighthouse) Data Center Campus
    Vantage Data Centers · company
  5. Vantage Data Centers and Wisconsin Building Trades Council Partner to Build Port Washington Data Center Development
    Business Wire · Oct 30, 2025 · company
  6. Wisconsin regulators send ATC back to the drawing board on data center connection project
    Wisconsin Watch · Aug 7, 2026 · news
  7. We Energies says Oracle dispute won't derail Port Washington data center
    Milwaukee Neighborhood News Service · Aug 4, 2026 · news
  8. ATC restarts push for grid upgrades serving Port Washington data center
    Wisconsin Watch · Sep 15, 2026 · news
  9. Ozaukee County Distribution Interconnection Project
    American Transmission Co. · Sep 2026 · utility
  10. Oracle America Cloud Services LLC v. Public Service Commission of Wisconsin, petition for review, Case No. 2026CV000256
    Ozaukee County Circuit Court (via WPR) · Jun 19, 2026 · court
  11. Port Washington council approves TID for $15B data center campus as residents continue to speak out
    WPR · Nov 5, 2025 · news
  12. Port Washington voters approve TID referendum
    WUWM · Apr 8, 2026 · news