Lower Ansonia Reservoir Dam
Lower Ansonia Reservoir Dam is an earth dam located in New Haven County, Connecticut, built in 1887. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Lower Ansonia Reservoir Dam
The primary purpose of Lower Ansonia Reservoir Dam is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by City Of Derby (local government). It impounds the Naugatuck River Trib near East Derby.
The dam stands 18 feet tall and stretches 423 feet across, creates a reservoir covering 9 acres, has a maximum storage capacity of 90 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1887, the structure is over a century old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 12/13/2021.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Connecticut dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Connecticut |
| County | New Haven |
| Nearest City | East Derby |
| River/Stream | Naugatuck River Trib |
| Coordinates | 41.31967, -73.07427 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 18 ft |
| Dam Height | 18 ft |
| Dam Length | 423 ft |
| Year Completed | 1887 (139 years old) |
Storage & Hydraulics
| NID Storage | 90 acre-ft |
| Max Storage | 90 acre-ft |
| Normal Storage | 71 acre-ft |
| Surface Area | 9 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 210 cfs |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Derby |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 12/13/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CT00027 |
| Federal ID | CT00027 |
| More Info | State Dam Safety Program |