Horsepen Dam

Horsepen Run· Loudoun, Virginia· Earth· 50 ft tall

High Hazard Water Supply Public Utility

Key Takeaway

Horsepen Dam is classified as high hazard in Virginia. Its primary use is water supply. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.

Physical Details

Dam Height	50 ft (taller than 92.9% in VA)
Dam Length	600 ft
Dam Type	Earth
Max Storage	15.2K acre-ft
Normal Storage	129 acre-ft

Surface Area	18 acres
Drainage Area	23 sq mi
NID ID	VA107007

Safety Information

High Hazard

Loss of human life is likely if the dam fails.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: Yes

Last Inspection: July 20, 2021

State Regulated: Yes

Regulatory Agency: Department of Conservation and Recreation

Ownership

Metro-Washington Airport Authority

Public Utility

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Moorefield Station East Swm Pond Dam

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Aol Dam No. 1

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Moorefield Station West Swm Pond Dam

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Farmwell Road and Estate Place Dam

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Dulles Airport Dam

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Frequently Asked Questions

What is the hazard classification of Horsepen Dam?

Horsepen Dam is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Horsepen Dam?

Horsepen Dam is owned by Metro-Washington Airport Authority (Public Utility). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

What is the primary purpose of Horsepen Dam?

Horsepen Dam serves the following purposes: Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Horsepen Dam?

Horsepen Dam has a dam height of 50 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.

When was Horsepen Dam last inspected?

Horsepen Dam was last inspected on July 20, 2021. Inspection dates indicate when a formal review occurred, not the results of that inspection.

Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.