Holly
Key Takeaway
Holly is classified as high hazard in Colorado. It was completed in 1979 and is 47 years old. Its primary use is flood risk reduction. 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 | 40 ft (taller than 81.3% in CO) |
| Dam Length | 1,170 ft |
| Dam Type | Earth |
| Max Storage | 455 acre-ft |
| Normal Storage | 0 acre-ft |
| Surface Area | 23 acres |
| Drainage Area | 2 sq mi |
| Max Discharge | 14,010 cfs |
| Year Completed | 1979 (47 years old) |
| NID ID | CO02214 |
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
URBAN DRAINAGE & FLOOD CONTROL DISTRICT (THOMAS, S
Local Government
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Significant Hazard 12 ftFrequently Asked Questions
What is the hazard classification of Holly?
Holly 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 Holly?
Holly is owned by URBAN DRAINAGE & FLOOD CONTROL DISTRICT (THOMAS, S (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Holly built?
Holly was completed in 1979, making it 47 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 Holly?
Holly serves the following purposes: Flood Risk Reduction. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.
How tall is Holly?
Holly has a dam height of 40 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 Holly last inspected?
Holly was last inspected on September 29, 2021. Inspection dates indicate when a formal review occurred, not the results of that inspection.