Nabnasset Pond Dam is an earth dam located in Middlesex County, Massachusetts, built in 1926. It carries a Significant hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 14 ft14 ft tall and 200 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic embankment section and the water level is illustrative.
About Nabnasset Pond Dam
The primary purpose of Nabnasset Pond 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 Westford (local government). It impounds the Blue Brook to Stony Brook near Westford.
The dam stands 14 feet tall and stretches 200 feet across, creates a reservoir covering 146 acres, has a maximum storage capacity of 1,454 acre-feet, and collects water from a drainage area of 1 square miles. Completed in 1926, the structure is well-established, with more than 75 years of service.
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 10/13/2021.
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Location
| State | Massachusetts |
| County | Middlesex |
| Nearest City | Westford |
| River/Stream | Blue Brook to Stony Brook |
| Coordinates | 42.61993, -71.41744 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 14 ft |
| Dam Length | 200 ft |
| Year Completed | 1926 (100 years old) |
Storage & Hydraulics
| NID Storage | 1,454 acre-ft |
| Max Storage | 1,454 acre-ft |
| Normal Storage | 961 acre-ft |
| Surface Area | 146 acres |
| Drainage Area | 1 sq mi |
| Max Discharge | 45 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | Town of Westford |
| Owner Type | Local Government |
| Hazard Classification | Significant |
| Condition Assessment | Fair |
| Last Inspection | 10/13/2021 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MA01182 |
| Federal ID | MA01182 |
| More Info | State Dam Safety Program |