Somersworth is a masonry dam located in Strafford County, New Hampshire, built in 1929. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
Dam profile
NID height · 17 ft17 ft tall and 400 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 Somersworth
The primary purpose of Somersworth 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 Aclara Meters LLC (private). It impounds the Salmon Falls River near Somersworth.
The dam stands 17 feet tall and stretches 400 feet across, creates a reservoir covering 55 acres, has a maximum storage capacity of 377 acre-feet, and collects water from a drainage area of 218 square miles. Completed in 1929, 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 satisfactory, indicating no existing or potential dam safety deficiencies are recognized. The most recent inspection on record was 05/19/2022.
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Location
| State | New Hampshire |
| County | Strafford |
| Nearest City | Somersworth |
| River/Stream | Salmon Falls River |
| Coordinates | 43.26480, -70.86370 |
Physical Characteristics
| Dam Type | Masonry |
| NID Height | 17 ft |
| Dam Height | 17 ft |
| Dam Length | 400 ft |
| Year Completed | 1929 (97 years old) |
Storage & Hydraulics
| NID Storage | 377 acre-ft |
| Max Storage | 377 acre-ft |
| Normal Storage | 377 acre-ft |
| Surface Area | 55 acres |
| Drainage Area | 218 sq mi |
| Max Discharge | 8,000 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Hydroelectric |
| Owner | Aclara Meters LLC |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 05/19/2022 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | NH00127 |
| Federal ID | NH00127 |
| More Info | State Dam Safety Program |