Ackley Lake Dam
Key Takeaway
Ackley Lake Dam is classified as high hazard in Montana. It was completed in 1938 and is 88 years old. Its primary use is irrigation. 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 | 55 ft (taller than 97.2% in MT) |
| Dam Length | 3,514 ft |
| Dam Type | Earth |
| Max Storage | 8.3K acre-ft |
| Normal Storage | 6.0K acre-ft |
| Surface Area | 260 acres |
| Drainage Area | 3 sq mi |
| Max Discharge | 1,410 cfs |
| Year Completed | 1938 (88 years old) |
| NID ID | MT00010 |
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
STATE WATER PROJECTS
State Government
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What is the hazard classification of Ackley Lake Dam?
Ackley Lake 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 Ackley Lake Dam?
Ackley Lake Dam is owned by STATE WATER PROJECTS (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Ackley Lake Dam built?
Ackley Lake Dam was completed in 1938, making it 88 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 Ackley Lake Dam?
Ackley Lake Dam serves the following purposes: Irrigation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Ackley Lake Dam?
Ackley Lake Dam has a dam height of 55 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 Ackley Lake Dam last inspected?
Ackley Lake Dam was last inspected on April 28, 2023. Inspection dates indicate when a formal review occurred, not the results of that inspection.