Holter Dam
Key Takeaway
Holter Dam is classified as high hazard in Montana. It was completed in 1918 and is 108 years old. Its primary use is hydroelectric. 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 | 124 ft (taller than 99.4% in MT) |
| Dam Length | 1,364 ft |
| Dam Type | Gravity |
| Max Storage | 306.0K acre-ft |
| Normal Storage | 245.0K acre-ft |
| Surface Area | 4,550 acres |
| Drainage Area | 17,150 sq mi |
| Max Discharge | 110,000 cfs |
| Year Completed | 1918 (108 years old) |
| NID ID | MT00559 |
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
NorthWestern Energy
Private
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Holter Dam?
Holter 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 Holter Dam?
Holter Dam is owned by NorthWestern Energy (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Holter Dam built?
Holter Dam was completed in 1918, making it 108 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 Holter Dam?
Holter Dam serves the following purposes: Hydroelectric, Flood Risk Reduction. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Holter Dam?
Holter Dam has a dam height of 124 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 Holter Dam last inspected?
Holter Dam was last inspected on August 2, 2021. Inspection dates indicate when a formal review occurred, not the results of that inspection.