Oneco Pond Dam is a masonry dam located in Windham County, Connecticut, built in 1900. It carries a Significant hazard potential classification.
Dam profile
NID height · 9 ft9 ft tall and 120 ft long. 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 Oneco Pond Dam
The primary purpose of Oneco Pond Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Hank Graff (private). It impounds the Moosup River near Sterling.
The dam stands 9 feet tall and stretches 120 feet across, creates a reservoir covering 12 acres, has a maximum storage capacity of 66 acre-feet, and collects water from a drainage area of 36 square miles. Completed in 1900, 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. An emergency action plan is in place for this dam.
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Location
| State | Connecticut |
| County | Windham |
| Nearest City | Sterling |
| River/Stream | Moosup River |
| Coordinates | 41.69347, -71.81065 |
Physical Characteristics
| Dam Type | Masonry |
| NID Height | 9 ft |
| Dam Height | 9 ft |
| Dam Length | 120 ft |
| Year Completed | 1900 (126 years old) |
Storage & Hydraulics
| NID Storage | 66 acre-ft |
| Max Storage | 66 acre-ft |
| Normal Storage | 66 acre-ft |
| Surface Area | 12 acres |
| Drainage Area | 36 sq mi |
| Max Discharge | 1,365 cfs |
Ownership & Safety
| Purpose | Recreation |
| Owner | Hank Graff |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Not assessed |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CT00611 |
| Federal ID | CT00611 |
| More Info | State Dam Safety Program |