West Fork Bitterroot (Painted Rocks)
Key Takeaway
West Fork Bitterroot (Painted Rocks) is classified as high hazard in Montana. It was completed in 1940 and is 86 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 | 143 ft (taller than 99.6% in MT) |
| Dam Length | 800 ft |
| Dam Type | Earth |
| Max Storage | 45.1K acre-ft |
| Normal Storage | 31.7K acre-ft |
| Surface Area | 655 acres |
| Drainage Area | 316 sq mi |
| Max Discharge | 3,300 cfs |
| Year Completed | 1940 (86 years old) |
| NID ID | MT00019 |
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
Frequently Asked Questions
What is the hazard classification of West Fork Bitterroot (Painted Rocks)?
West Fork Bitterroot (Painted Rocks) 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 West Fork Bitterroot (Painted Rocks)?
West Fork Bitterroot (Painted Rocks) is owned by STATE WATER PROJECTS (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was West Fork Bitterroot (Painted Rocks) built?
West Fork Bitterroot (Painted Rocks) was completed in 1940, making it 86 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 West Fork Bitterroot (Painted Rocks)?
West Fork Bitterroot (Painted Rocks) 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 West Fork Bitterroot (Painted Rocks)?
West Fork Bitterroot (Painted Rocks) has a dam height of 143 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 West Fork Bitterroot (Painted Rocks) last inspected?
West Fork Bitterroot (Painted Rocks) was last inspected on October 17, 2023. Inspection dates indicate when a formal review occurred, not the results of that inspection.