Cochrane
Key Takeaway
Cochrane is classified as high hazard in Montana. It was completed in 1957 and is 69 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 | 100 ft (taller than 99% in MT) |
| Dam Length | 856 ft |
| Dam Type | Gravity |
| Normal Storage | 8.5K acre-ft |
| Surface Area | 249 acres |
| Drainage Area | 23,270 sq mi |
| Max Discharge | 140,000 cfs |
| Year Completed | 1957 (69 years old) |
| NID ID | MT00556 |
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
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Low Hazard 36 ftFrequently Asked Questions
What is the hazard classification of Cochrane?
Cochrane 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 Cochrane?
Cochrane is owned by NorthWestern Energy (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Cochrane built?
Cochrane was completed in 1957, making it 69 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 Cochrane?
Cochrane 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 Cochrane?
Cochrane has a dam height of 100 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 Cochrane last inspected?
Cochrane was last inspected on August 12, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.