WaterMark / Jurisdictions / Loudoun County, VA
Loudoun County, VA: Data Center Water Impact
Reference data for evaluating a data center proposal in Loudoun County, VA. Every figure below is a stored value with its primary source attached. Facility-scale results are produced by the assessment tool.
Water supply
| Metric | Value | Source / basis |
|---|---|---|
| Water utility | Loudoun Water | Utility of record |
| Supply source | Potomac River / Goose Creek Reservoir | Utility of record |
| Treatment capacity | 62 MGD | Water stress: WRI Aqueduct 4.0, HUC-8 basin 02070008. Utility data: Loudoun Water 2024 Annual Report. |
| Water rate | $8.65 / 1,000 gal | Loudoun Water published rate schedule |
| Watershed stress | High (3.4 / 5) | Water stress: WRI Aqueduct 4.0, HUC-8 basin 02070008. Utility data: Loudoun Water 2024 Annual Report. |
Watershed consumptive use
Basin: Middle Potomac-Catoctin (HUC-8 02070008). Figures are consumptive use, not withdrawal, because evaporative data center loss is consumptive. USGS data year 2020.
| Category | Consumptive use (MGD) | Share of basin |
|---|---|---|
| Residential | 6 | 16.5% |
| Thermoelectric power | 3 | 8.2% |
| Industrial | 1 | 2.7% |
| Irrigation | 1 | 2.7% |
| Mining | 0.4 | 1.1% |
| Existing data centers | 25 | 68.7% |
| Total | 36.4 | 100.0% |
Total is the sum of the categories listed above. Shares are each category divided by that total. Source: USGS Water Use 2020, Loudoun County. Existing data center segment: Loudoun Water non-residential customer reports.
Grid generation water (Scope 2)
Generating the electricity a data center consumes evaporates water at the power plant. That volume is real, it is attributable, and it is excluded from most corporate "water positive" accounting. On a thermal grid it is frequently comparable to the facility's own cooling water.
| Metric | Value | Source / basis |
|---|---|---|
| Grid region | PJM Interconnection | PJM |
| Electric utility | Dominion Energy | Utility of record |
| Grid water intensity | 0.42 gal / kWh | Macknick et al. 2012 consumption factors, weighted by PJM GATS EY2024 generation mix |
| Local peak demand | 1,200 MW | PJM |
| Modeled rate impact | 10% to 20% | See methodology |
Where this water is consumed: PJM grid plants serving Loudoun are distributed across MD, VA, PA, OH and WV. Scope 2 water for the existing Data Center Alley load is consumed largely outside the local Potomac basin.
Run this county at your facility size. The assessment tool computes direct (Scope 1) and indirect (Scope 2) water for a specific load, cooling system, and mitigation stack, with the same citations attached.
Reducing the footprint here
A high stress reading is a design constraint, not a verdict. Closed-loop and dry or hybrid cooling, adiabatic assist, immersion, and reclaimed or non-potable sourcing each move the direct number, and siting against a cleaner grid mix moves the indirect number. The solutions catalog lists each option with its water reduction, its energy and cost tradeoff, and its source.
Regulatory and siting status
Data Center Alley — saturated. ~25 MGD existing DC consumptive use; transmission constraints; growing community pushback. On 22 Jul 2026 the Board of Supervisors voted 6-1 to direct staff to prepare a temporary pause on new data center applications, site plans, and substations, for decision 15 Sep 2026. Nothing is adopted; the County Attorney has said he does not believe the Board has authority under the Dillon Rule to impose one. A separate item ending the grandfathering of pre-Feb 2025 by-right applications is set for introduction 1 Sep 2026.
- Hyperscale activity
- High existing data center load
Sources: Water: Loudoun Water 2024 report. Grid: PJM. Incentives: VA Code §58.1-609.3. Pause proposal: Virginia Business, Jul 2026; Virginia Mercury, 17 Aug 2026. Grandfathering repeal: Virginia Business, 21 Aug 2026.
Comparative siting scores for this county, alongside every other county tracked, are on the US Siting Matrix.
Related counties
| County | Water source | Watershed stress |
|---|---|---|
| Prince William County, VA | Occoquan Reservoir | High (3.4/5) |
| Henrico County, VA | James River | Medium (2.6/5) |
| Mecklenburg County, VA | Roanoke River / Buggs Island Lake | Low-Medium (1.8/5) |
| Spotsylvania County, VA | Rappahannock River | Medium (2.4/5) |
| Frederick County, VA | Shenandoah River + Anderson Lake | Low-Medium (2/5) |
How these numbers are derived
Assumptions, formulas, and the full source list are in the methodology. WaterMark is published by Standard Water Corp and is not affiliated with any data center developer, utility, or government agency.