Potomac River Dam #4
Key Takeaway
Potomac River Dam #4 is classified as significant hazard in Maryland. It was completed in 1869 and is 157 years old. Its primary use is hydroelectric. Significant hazard means failure could cause economic or environmental damage. Learn more.
Physical Details
| Dam Height | 20 ft (taller than 41.2% in MD) |
| Dam Length | 715 ft |
| Dam Type | Gravity |
| Max Storage | 6.8K acre-ft |
| Surface Area | 675 acres |
| Drainage Area | 5,900 sq mi |
| Max Discharge | 1,000,000 cfs |
| Year Completed | 1869 (157 years old) |
| Year Modified | 1994 |
| NID ID | MD00078 |
Safety Information
No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities.
Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?
Ownership
DOI NPS
Federal Government
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Low Hazard 22 ftFrequently Asked Questions
What is the hazard classification of Potomac River Dam #4?
Potomac River Dam #4 is classified as Significant Hazard. No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.
Who owns and operates Potomac River Dam #4?
Potomac River Dam #4 is owned by DOI NPS (Federal Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Potomac River Dam #4 built?
Potomac River Dam #4 was completed in 1869, making it 157 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.
What is the primary purpose of Potomac River Dam #4?
Potomac River Dam #4 serves the following purposes: Hydroelectric. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Potomac River Dam #4?
Potomac River Dam #4 has a dam height of 20 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 Potomac River Dam #4 last inspected?
Potomac River Dam #4 was last inspected on July 26, 2023. Inspection dates indicate when a formal review occurred, not the results of that inspection.