Mianus River Dam
Mianus River Dam is a concrete dam located in Fairfield County, Connecticut, built in 1920. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
About Mianus River Dam
The primary purpose of Mianus River Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Town Of Greenwich (local government). It impounds the Mianus River near Greenwich.
The dam stands 20 feet tall and stretches 350 feet across, creates a reservoir covering 48 acres, has a maximum storage capacity of 525 acre-feet, and collects water from a drainage area of 30 square miles. Completed in 1920, 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. The most recent inspection on record was 04/29/2021.
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Location
| State | Connecticut |
| County | Fairfield |
| Nearest City | Greenwich |
| River/Stream | Mianus River |
| Coordinates | 41.04277, -73.58937 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 20 ft |
| Dam Height | 20 ft |
| Dam Length | 350 ft |
| Year Completed | 1920 (106 years old) |
Storage & Hydraulics
| NID Storage | 525 acre-ft |
| Max Storage | 525 acre-ft |
| Normal Storage | 525 acre-ft |
| Surface Area | 48 acres |
| Drainage Area | 30 sq mi |
| Max Discharge | 10,158 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Town of Greenwich |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 04/29/2021 |
| Emergency Action Plan | No |
Identifiers
| NID ID | CT00045 |
| Federal ID | CT00045 |
| More Info | State Dam Safety Program |