Dulles Airport Dam Reservoir Report

Last Updated: December 22, 2025

The Dulles Airport Dam, located in Loudoun County, Virginia, serves as a crucial water supply infrastructure managed by a public utility.


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Summary

This earth-type dam on Horsepen Run stands at 11.4 feet high and 650 feet long, with a storage capacity of 259 acre-feet and a surface area of 28 acres. While its condition assessment is currently not rated, the dam is under state regulation, permitting, inspection, and enforcement by the Department of Conservation and Recreation, ensuring its safety and compliance with standards.

With a primary purpose of water supply, the Dulles Airport Dam plays a significant role in meeting the water needs of the local community. Although the dam's hazard potential is deemed significant, it has not experienced any recent modifications or emergency preparedness updates. The last inspection in March 2017 indicated compliance with safety guidelines, but further assessments and risk management measures may be necessary to address potential risks and ensure the dam's continued reliability and functionality for water resource sustainability in the region.

Overall, the Dulles Airport Dam represents a vital component of Virginia's water infrastructure, contributing to the management of Horsepen Run's drainage area and providing essential water storage capacity. As climate change impacts water resources, monitoring and maintaining the dam's integrity will be crucial to safeguarding water supply reliability and addressing potential hazards. Collaboration between state agencies, regulators, and stakeholders will be essential to ensure the continued operation and safety of this important water resource asset.

Dam Length

650

Dam Height

11.4

River Or Stream

TR-Horsepen Run

Primary Dam Type

Earth

Surface Area

28

Hydraulic Height

11.4

Drainage Area

1.42

Nid Storage

259

Structural Height

11.4

Hazard Potential

Significant

Nid Height

11
       
Seasonal Comparison

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Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.