Assabet is a masonry dam located in Middlesex County, Massachusetts, built in 1921. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 13 ft13 ft tall and 480 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 Assabet
The primary purpose of Assabet 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 Acton Hydro Company, Inc. (private). It impounds the Assabet River near Concord.
The dam stands 13 feet tall and stretches 480 feet across, creates a reservoir covering 30 acres, has a maximum storage capacity of 122 acre-feet, and collects water from a drainage area of 123 square miles. Completed in 1921, 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 06/16/2022.
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Location
| State | Massachusetts |
| County | Middlesex |
| Nearest City | Concord |
| River/Stream | Assabet River |
| Coordinates | 42.44010, -71.43200 |
Physical Characteristics
| Dam Type | Masonry |
| NID Height | 13 ft |
| Dam Height | 13 ft |
| Dam Length | 480 ft |
| Year Completed | 1921 (105 years old) |
Storage & Hydraulics
| NID Storage | 122 acre-ft |
| Max Storage | 122 acre-ft |
| Normal Storage | 122 acre-ft |
| Surface Area | 30 acres |
| Drainage Area | 123 sq mi |
| Max Discharge | 3,350 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Acton Hydro Company, Inc. |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/16/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MA00128 |
| Federal ID | MA00128 |
| More Info | State Dam Safety Program |