Unionville Pond Dam
Unionville Pond Dam is an earth dam located in Worcester County, Massachusetts, built in 1909. It carries a Significant hazard potential classification and has a fair condition assessment.
About Unionville Pond Dam
The primary purpose of Unionville Pond Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Ma Department Of Conservation & Recreation (state). It impounds the Chaffins Brook near Holden.
The dam stands 21 feet tall and stretches 200 feet across, creates a reservoir covering 19 acres, has a maximum storage capacity of 380 acre-feet, and collects water from a drainage area of 6 square miles. Completed in 1909, 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 fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. An emergency action plan is in place for this dam. The most recent inspection on record was 06/02/2022.
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Location
| State | Massachusetts |
| County | Worcester |
| Nearest City | Holden |
| River/Stream | Chaffins Brook |
| Coordinates | 42.36139, -71.83901 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 21 ft |
| Dam Length | 200 ft |
| Year Completed | 1909 (117 years old) |
Storage & Hydraulics
| NID Storage | 380 acre-ft |
| Max Storage | 380 acre-ft |
| Normal Storage | 100 acre-ft |
| Surface Area | 19 acres |
| Drainage Area | 6 sq mi |
| Max Discharge | 187 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | MA Department of Conservation & Recreation |
| Owner Type | State |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 06/02/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MA00620 |
| Federal ID | MA00620 |
| More Info | State Dam Safety Program |