DEQ Requires Microsoft to Pay $2.5M for Leesburg Data Center Air Pollution
Microsoft has been ordered by the Virginia Department of Environmental Quality (DEQ) to pay $2.5 million for exceeding air quality permits at its Leesburg data center. This violation occurred after a substation failure caused the facility to rely on backup diesel generators for seven days. The Loudoun County Board of Supervisors is also researching ways to regulate data center generator usage.
The Virginia Department of Environmental Quality (DEQ) has mandated that Microsoft pay $2.5 million in penalties for violating air quality permits at one of its Leesburg data centers. The violation stemmed from a catastrophic failure of the Cochran Mill electrical substation on June 27, 2025, which forced the data center to operate 62 emergency diesel generators for seven days.
Microsoft's permit for the data center limits fuel consumption and emissions of various pollutants, including nitrogen oxides and particulate matter. The DEQ's order by consent stated that Microsoft exceeded these limits during the extended outage. Following a notice of violation, Microsoft initially challenged the DEQ's emission calculation methodology but later provided stack testing data that confirmed the exceedances. As part of the settlement, Microsoft will also invest $31 million in a dual-feed system to reduce future power failure risks, and $2.4 million of the penalty will fund mobile air monitoring stations and sensors in Northern Virginia.
The Piedmont Environmental Council (PEC) has consistently raised concerns about data center emissions in the region, arguing that while individual data centers may meet DEQ standards, the cumulative impact of Loudoun County's extensive data center development is not adequately analyzed. PEC Senior Land Use Field Representative Gem Bingol highlighted the need for cumulative analysis, contrasting it with DEQ's focus on individual facility compliance.
In response to ongoing concerns, Supervisor Koran T. Saines (D-Sterling) of the Loudoun County Board of Supervisors is leading an initiative to research potential county regulations on data center backup generator usage. This effort, which received support in July, is currently underway, though a timeline for proposals is not yet available.