The Potomac hasn’t been this low in recorded history. Millions of Marylanders depend on it. And a sprawling industry upstream faces no meaningful limits on how much it can drink.
By Michael Phillips | MDBayNews
The Potomac River is at the lowest level ever recorded for this time of year — a data point drawn from more than 130 years of measurements — and the region that depends on it for drinking water is heading into summer with no secondary source, no rain in the forecast sufficient to reverse the trend, and a new and growing drain that wasn’t a serious factor the last time the basin ran this dry.
That drain is Northern Virginia’s data center industry. And Maryland, despite bearing much of the downstream risk, has no formal voice in how Virginia permits, regulates, or limits it.
The U.S. Drought Monitor placed 31% of the D.C. region in severe drought as of last week, with the remainder in moderate drought. The Interstate Commission on the Potomac River Basin — the interstate body that manages the river’s water supply — issued its April outlook, finding an above-normal probability that backup reservoirs will need to be tapped this summer or fall. That would be the first such release in more than a decade; the last time the Army Corps of Engineers was asked to release water from the upstream reservoirs was 2010.
“It’s been over 10 years since we asked the Army Corps of Engineers to release water from the reservoirs on the Potomac River,” ICPRB Executive Director Michael Nardolilli said. “The likelihood of releases from the backup reservoirs is increasing.”
The river is the sole source of drinking water for Washington D.C. and Arlington County, and the primary source for the Maryland and Virginia suburbs. WSSC Water — which serves 1.9 million customers across Montgomery and Prince George’s counties — draws the majority of its supply from the Potomac, supplemented by the Patuxent River system. The region’s three major water utilities, D.C. Water, WSSC Water, and Fairfax Water, share access to three backup reservoirs when the Potomac flows drop too low. The closest of those is Little Seneca Reservoir, in Montgomery County, Maryland.
In other words, the emergency buffer for a multi-state, multi-million-person water system sits in Maryland.
One River. No Backup. One State Calling the Shots.
The data center problem is structural. Loudoun County, Virginia — which hosts what experts describe as the world’s largest concentration of data centers, with more than 200 facilities built and over 100 more in the development pipeline — sits along the Potomac watershed. Water used to cool server equipment represents a significant and growing share of total basin withdrawals.
According to the Piedmont Environmental Council, Loudoun County’s data centers account for roughly 2 to 3 percent of total water withdrawals from the Potomac basin under normal conditions. During peak summer months, when cooling demand spikes alongside regional drought risk, that figure can climb to 8 percent.
To put that in context: Maryland residents are asked to limit lawn watering and car washing during drought advisories. A single county in Virginia can quietly draw eight cents of every dollar of water the river produces in summer, with no disclosure requirement, no individual facility reporting mandate, and no obligation to coordinate with downstream states.
Maryland is being told to conserve water while a single county upstream can quietly take up to 8 percent of the Potomac at peak demand.
The American Rivers organization named the Potomac the most endangered river in the United States for 2026, citing both the data center expansion and the impact of a major sewage spill in January that sent more than 300 million gallons of raw sewage into the river following a pipeline collapse in Cabin John, Maryland. That spill — caused by infrastructure failure, not data centers — led Maryland and the Justice Department to file suit against DC Water last week. But conservationists and water managers are now pointing to the data center issue as a longer-term structural threat.
“There needs to be transparency and a cumulative assessment of how these facilities impact water supplies,” Potomac Conservancy Director Matt Calvert said in the organization’s response to the most-endangered designation.
What Virginia Did — And What It Didn’t
Virginia’s General Assembly was not asleep. The 2026 session saw lawmakers file more than 60 bills aimed at the data center industry. Of those, 15 passed and were sent to Governor Abigail Spanberger’s desk.
One of the water-related measures that cleared the legislature — Senate Bill 553 — requires utilities to report monthly water volumes supplied to data centers to the state’s Department of Environmental Quality. Reporting begins in 2027.
That sounds like progress. It isn’t enough.
The Potomac Conservancy, which lobbied for the bill, acknowledged that the final version was weakened during the legislative process. As written, SB 553 requires utility-level reporting, not individual facility disclosure. It does not mandate reporting of peak daily usage, nor does it require any assessment of water consumption for proposed new data centers before they’re approved. The numbers it will eventually produce will be aggregates — useful to analysts, invisible to affected communities.
The bigger transparency battle remains unsettled. Virginia data centers are not currently required to report detailed individual water usage, and localities approving new data center projects are under no obligation to evaluate cumulative water consumption impacts before issuing permits. According to the Piedmont Environmental Council, peak summer usage from data centers can reach up to three times average monthly demand and as much as ten times average daily demand — precisely when the Potomac is most stressed and when Maryland water managers are watching river flows most closely.
The industry’s leverage in Richmond is formidable. Virginia currently provides data centers roughly $1.6 billion annually in sales tax exemptions — the largest such incentive in the state for any single industry. A battle to eliminate or condition that exemption consumed the 2026 legislative session and remains unresolved; Spanberger called a special session for April 23 to settle the budget standoff it created.
Maryland has no seat at that table.
The Infrastructure Gap Maryland Can’t Solve Alone
The ICPRB’s December 2025 water supply study — the commission’s comprehensive review, published every five years — found that in four out of nine modeled extreme drought scenarios, the backup reservoir system could run out of water as early as 2030. The commission described the D.C. region as uniquely vulnerable: it is the only major metropolitan area in the United States that relies on a single river as its primary source and maintains less than one day of backup water supply on hand at any given time.
The leading proposed solution is converting the Travilah Quarry in Rockville, Maryland, into a large-scale backup reservoir — filled during wet periods, drawn down during droughts. The U.S. Army Corps of Engineers launched a feasibility study for the project, known as “quarry, plus,” funded in part by the Metropolitan Washington Council of Governments. But the study’s timeline depends on federal funding that, as ICPRB has noted, is currently uncertain.
The D.C. region is the only major metro in America relying on a single river — with less than one day of backup water supply.
That uncertainty is not abstract. A three-year federal feasibility study with federal funding in limbo, on a 2030 risk horizon, is not a comfortable position for a region where 69 percent of Maryland is currently under drought conditions.
WSSC Water CEO Kishia L. Powell put the challenge plainly in the commission’s December report: “The Potomac River has provided the vast majority of the region’s drinking water for generations. But climate pressures and growing demand will impact our ability to meet the region’s needs in just a few years.”
What Maryland’s Leaders Owe Marylanders
The drought is not Virginia’s fault. Data centers moving to Northern Virginia is not, by itself, an act of malice against Maryland’s water supply. The interstate cooperation framework the ICPRB operates under has served the region well for decades, and Virginia’s 2026 legislature made more of an effort on data center transparency than many previous sessions did.
But accountability journalism requires noting what is true: Maryland has approximately 69 percent of its landmass under drought conditions right now, its primary source of drinking water is at historic lows, the most important emergency backup reservoir is in Montgomery County, and the single largest new variable in the basin’s water demand picture — data center cooling in Loudoun County — faces no individual disclosure requirements, no cumulative impact reviews at permitting, and no interstate coordination obligation, until at least 2027, and only at the aggregate level even then.
One river supplies millions. One state controls the spigot. And Maryland doesn’t have a seat at the table.
The Moore administration has been vocal about protecting Marylanders from federal threats and regional economic pressures. Protecting the state’s water supply from unregulated upstream demand is, by any reasonable definition, the same type of problem.
Maryland’s congressional delegation and the Moore administration should be pressing ICPRB to formalize water-demand limits on basin-wide industrial users as part of the compact’s existing authority. Maryland and Virginia should be in direct negotiation — outside the legislative session calendar — about what data center water reporting means for shared resource management. And WSSC Water’s drought contingency plans, the status of the Travilah Quarry feasibility study, and the Army Corps timeline should be part of the public record Marylanders can access, not buried in commission technical reports.
The river is at record lows. The summer hasn’t started yet.
Sources: Interstate Commission on the Potomac River Basin, April 2026 Water Supply Outlook; ICPRB, 2025 Washington Metropolitan Area Water Supply Study (December 2025); U.S. Drought Monitor, April 17, 2026; Piedmont Environmental Council, April 2026 statement; American Rivers, 2026 Most Endangered Rivers Report; WSSC Water; MultiState Policy Watch; Virginia Mercury; Maryland Matters/WTOP; Potomac Conservancy.
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