Hammonasset Dam
Hammonasset Dam is a concrete dam located in New Haven County, Connecticut, built in 1956. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Hammonasset Dam
The primary purpose of Hammonasset 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 South Central Ct Rwa (public utility). It impounds the Hammonasset River near Clinton.
The dam stands 63 feet tall and stretches 447 feet across, creates a reservoir covering 280 acres, has a storage capacity of 4,300 acre-feet, and collects water from a drainage area of 19 square miles. Completed in 1956, the structure is well into its service life at over 50 years 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 10/16/2024.
At 63 feet, this dam is taller than 96% of all dams in the United States.
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 | Clinton |
| River/Stream | Hammonasset River |
| Coordinates | 41.35815, -72.61253 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 63 ft |
| Dam Height | 63 ft |
| Dam Length | 447 ft |
| Year Completed | 1956 (70 years old) |
Storage & Hydraulics
| NID Storage | 4,300 acre-ft |
| Normal Storage | 4,300 acre-ft |
| Surface Area | 280 acres |
| Drainage Area | 19 sq mi |
| Max Discharge | 14,385 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | South Central CT RWA |
| Owner Type | Public Utility |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 10/16/2024 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CT00400 |
| Federal ID | CT00400 |
| More Info | State Dam Safety Program |