Potomac River Named Most Endangered in U.S. for 2026, Citing Data Center Growth and Water Demands

The Potomac River ranks as the most endangered river in the U.S. according to American Rivers’ 2026 list, released this month. The designation is largely driven by rapid, uncontrolled data center expansion in the watershed and by the impacts of a major sewage spill into the river in January 2026.

The Piedmont Environmental Council (PEC) issued a statement on April 16 in response to the report. PEC President Chris Miller stated that the listing underscores the cumulative impacts of data centers on natural resources, including access to clean and abundant water that serves the Washington metropolitan area.

Loudoun County, home to one of the world’s largest concentrations of data centers and bordering the Potomac River, accounts for roughly 2–3% of total water withdrawals from the basin. That figure can rise to as high as 8% during the peak summer months, when cooling demand is highest. The PEC statement identified three main issues surrounding data center water usage in Virginia:

– Insufficient transparency: Data centers are not currently required to report detailed water usage, and localities are not mandated to evaluate water consumption when approving new projects. Peak summer usage can reach up to three times the average monthly demand and as much as ten times the average daily demand, coinciding with periods of heightened drought risk and increased regional water use.

– Lack of cumulative impact assessment: Virginia has more than 600 data centers. While individual facilities may not pose a severe strain, their combined water and electricity demands—especially peak daily usage during drier late-summer conditions—lack comprehensive statewide tracking. These impacts extend beyond local jurisdictions, affecting households, farms, hospitals, schools, and other users.

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