Grupes Reservoir Dam
Key Takeaway
Grupes Reservoir Dam is classified as high hazard in Connecticut. It was completed in 1871 and is 155 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 | 24 ft (taller than 81.2% in CT) |
| Dam Length | 235 ft |
| Dam Type | Concrete |
| Max Storage | 311 acre-ft |
| Normal Storage | 171 acre-ft |
| Surface Area | 23 acres |
| Drainage Area | 10 sq mi |
| Max Discharge | 2,900 cfs |
| Year Completed | 1871 (155 years old) |
| NID ID | CT00057 |
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
City of Norwalk
Local Government
Nearby Dams
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Significant Hazard 18 ftNew Canaan Reservoir Dam
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Significant Hazard 5 ftSiscowit Reservoir Dam
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Significant Hazard 6 ftFrequently Asked Questions
What is the hazard classification of Grupes Reservoir Dam?
Grupes 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 Grupes Reservoir Dam?
Grupes Reservoir Dam is owned by City of Norwalk (Local Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.
When was Grupes Reservoir Dam built?
Grupes Reservoir Dam was completed in 1871, making it 155 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 Grupes Reservoir Dam?
Grupes 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 Grupes Reservoir Dam?
Grupes Reservoir Dam has a dam height of 24 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 Grupes Reservoir Dam last inspected?
Grupes Reservoir Dam was last inspected on April 17, 2019. Inspection dates indicate when a formal review occurred, not the results of that inspection.