Ish #3 (Main Dam)
Key Takeaway
Ish #3 (Main Dam) is classified as high hazard in Colorado. It was completed in 1905 and is 121 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 | 42 ft (taller than 83.3% in CO) |
| Dam Length | 6,700 ft |
| Dam Type | Earth |
| Max Storage | 9.1K acre-ft |
| Normal Storage | 7.1K acre-ft |
| Surface Area | 314 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 3,066 cfs |
| Year Completed | 1905 (121 years old) |
| Year Modified | 2003 |
| NID ID | CO01771 |
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
THE ISH RESERVOIR COMPANY
Private
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Significant Hazard 26 ftFrequently Asked Questions
What is the hazard classification of Ish #3 (Main Dam)?
Ish #3 (Main Dam) 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 Ish #3 (Main Dam)?
Ish #3 (Main Dam) is owned by THE ISH RESERVOIR COMPANY (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Ish #3 (Main Dam) built?
Ish #3 (Main Dam) was completed in 1905, making it 121 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 Ish #3 (Main Dam)?
Ish #3 (Main Dam) 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 Ish #3 (Main Dam)?
Ish #3 (Main Dam) has a dam height of 42 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 Ish #3 (Main Dam) last inspected?
Ish #3 (Main Dam) was last inspected on July 20, 2022. Inspection dates indicate when a formal review occurred, not the results of that inspection.