Lake John D Long
Key Takeaway
Lake John D Long is classified as high hazard in South Carolina. It was completed in 1978 and is 48 years old. Its primary use is recreation. 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 | 49 ft (taller than 96.3% in SC) |
| Max Storage | 2.1K acre-ft |
| Normal Storage | 1.2K acre-ft |
| Surface Area | 81 acres |
| Year Completed | 1978 (48 years old) |
| NID ID | SC01523 |
Safety Information
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?
Ownership
SC DEPARTMENT OF NATURAL RESOURCES
State Government
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Significant Hazard 36 ftFrequently Asked Questions
What is the hazard classification of Lake John D Long?
Lake John D Long 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 Lake John D Long?
Lake John D Long is owned by SC DEPARTMENT OF NATURAL RESOURCES (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Lake John D Long built?
Lake John D Long was completed in 1978, making it 48 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 Lake John D Long?
Lake John D Long serves the following purposes: Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Lake John D Long?
Lake John D Long has a dam height of 49 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 Lake John D Long last inspected?
Lake John D Long was last inspected on March 21, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.