Tunnel Dam Hydro Station is a concrete dam located in New London County, Connecticut, built in 1906. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 32 ft32 ft tall and 780 ft long, taller than 74% of U.S. dams with a recorded height. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Tunnel Dam Hydro Station
The primary purpose of Tunnel Dam Hydro Station is hydroelectric. The dam generates hydroelectric power by channeling water through turbines, converting the energy of flowing water into electricity. The dam is owned by Firstlight Power Resources (public utility). It impounds the Quinebaug River near Preston.
The dam stands 32 feet tall and stretches 780 feet across, creates a reservoir covering 100 acres, has a maximum storage capacity of 1,650 acre-feet, and collects water from a drainage area of 744 square miles. Completed in 1906, the structure is over a century old.
This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. 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 11/18/2021.
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Location
| State | Connecticut |
| County | New London |
| Nearest City | Preston |
| River/Stream | Quinebaug River |
| Coordinates | 41.55496, -72.04095 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 32 ft |
| Dam Height | 32 ft |
| Dam Length | 780 ft |
| Year Completed | 1906 (120 years old) |
Storage & Hydraulics
| NID Storage | 1,650 acre-ft |
| Max Storage | 1,650 acre-ft |
| Normal Storage | 1,650 acre-ft |
| Surface Area | 100 acres |
| Drainage Area | 744 sq mi |
| Max Discharge | 33,940 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Firstlight Power Resources |
| Owner Type | Public Utility |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 11/18/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CT00637 |
| Federal ID | CT00637 |
| More Info | State Dam Safety Program |