56th largest plant in New Hampshire · 12185th nationally
Somersworth Lower Great Dam is a hydroelectric power plant in New Hampshire with a nameplate capacity of 1.3 MW. It generates roughly 5.0k MWh per year — enough to power about 472 average U.S. homes.
Its capacity factor of 44% puts it in the middle range — running steadily but not full-time.
| Plant Name | Somersworth Lower Great Dam |
|---|---|
| Operator | Green Mountain Power Corp |
| City | Somersworth |
| County | Strafford County |
| State | New Hampshire |
| ZIP | 03878 |
| Coordinates | 43.25111, -70.84083 |
This plant highlighted in navy-ringed pin; other generators within 25 miles shown as fuel-colored dots.
| ID | Technology | Fuel | Capacity | Status | Online |
|---|---|---|---|---|---|
| GEN1 | Conventional Hydroelectric | Water | 1.3 MW | Operating | 1985 |
| NERC Region | NPCC |
|---|---|
| Balancing Authority | Iso New England Inc. |
Hydroelectric plants spin turbines using falling or flowing water — typically from a dam-impounded reservoir. They are dispatchable, long-lived, and emission-free at the point of generation, though large reservoirs can disrupt rivers and ecosystems and methane can be released from flooded vegetation.