Big Lake
Key Takeaway
Big Lake is classified as significant hazard in Montana. It was completed in 1915 and is 111 years old. Its primary use is water supply. Significant hazard means failure could cause economic or environmental damage. Learn more.
Physical Details
| Dam Height | 30 ft (taller than 82.7% in MT) |
| Dam Length | 440 ft |
| Dam Type | Earth |
| Max Storage | 621 acre-ft |
| Normal Storage | 143 acre-ft |
| Surface Area | 38 acres |
| Drainage Area | 4 sq mi |
| Max Discharge | 95 cfs |
| Year Completed | 1915 (111 years old) |
| Year Modified | 2010 |
| NID ID | MT01465 |
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
CITY OF MISSOULA
Local Government
Nearby Dams
Frequently Asked Questions
What is the hazard classification of Big Lake?
Big Lake 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 Big Lake?
Big Lake is owned by CITY OF MISSOULA (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Big Lake built?
Big Lake was completed in 1915, making it 111 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 Big Lake?
Big Lake serves the following purposes: Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Big Lake?
Big Lake has a dam height of 30 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 Big Lake last inspected?
Big Lake was last inspected on August 1, 2017. Inspection dates indicate when a formal review occurred, not the results of that inspection.