Alto Pass Reservoir Dam
Key Takeaway
Alto Pass Reservoir Dam is classified as high hazard in Illinois. It was completed in 1964 and is 62 years old. Its primary use is water supply. 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 | 45 ft (taller than 88% in IL) |
| Dam Length | 450 ft |
| Dam Type | Earth |
| Max Storage | 296 acre-ft |
| Normal Storage | 168 acre-ft |
| Surface Area | 15 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 1,900 cfs |
| Year Completed | 1964 (62 years old) |
| NID ID | IL00064 |
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
ALTO PASS WD
Local Government
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Low Hazard 40 ftFrequently Asked Questions
What is the hazard classification of Alto Pass Reservoir Dam?
Alto Pass Reservoir 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 Alto Pass Reservoir Dam?
Alto Pass Reservoir Dam is owned by ALTO PASS WD (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Alto Pass Reservoir Dam built?
Alto Pass Reservoir Dam was completed in 1964, making it 62 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 Alto Pass Reservoir Dam?
Alto Pass Reservoir Dam 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 Alto Pass Reservoir Dam?
Alto Pass Reservoir Dam has a dam height of 45 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 Alto Pass Reservoir Dam last inspected?
Alto Pass Reservoir Dam was last inspected on October 4, 2023. Inspection dates indicate when a formal review occurred, not the results of that inspection.