Six Mile - Main
Key Takeaway
Six Mile - Main is classified as high hazard in Colorado. It was completed in 1892 and is 134 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 | 35 ft (taller than 75.7% in CO) |
| Dam Length | 3,050 ft |
| Dam Type | Earth |
| Max Storage | 2.2K acre-ft |
| Normal Storage | 1.4K acre-ft |
| Surface Area | 124 acres |
| Drainage Area | 3 sq mi |
| Max Discharge | 11,552 cfs |
| Year Completed | 1892 (134 years old) |
| NID ID | CO00250 |
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
BOULDER & WHITE ROCK DITCH & RESERVOIR CO. (GRANT,
Private
Nearby Dams
Boulder - South
Boulder, CO
High Hazard 45 ftSix Mile - Northwest
Boulder, CO
Low Hazard 14 ftBoulder - North
Boulder, CO
High Hazard 44 ftDavis No. 2
Boulder, CO
Low Hazard 11 ftDavis No. 1
Boulder, CO
High Hazard 10 ftHayden
Boulder, CO
High Hazard 27 ftSt. Joe Tailings
Boulder, CO
Low Hazard 37 ftLeggett & Hillcrest
Boulder, CO
High Hazard 28 ftFrequently Asked Questions
What is the hazard classification of Six Mile - Main?
Six Mile - Main 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 Six Mile - Main?
Six Mile - Main is owned by BOULDER & WHITE ROCK DITCH & RESERVOIR CO. (GRANT, (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Six Mile - Main built?
Six Mile - Main was completed in 1892, making it 134 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 Six Mile - Main?
Six Mile - Main serves the following purposes: Irrigation, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Six Mile - Main?
Six Mile - Main has a dam height of 35 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 Six Mile - Main last inspected?
Six Mile - Main was last inspected on August 9, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.