47th largest plant in Montana · 5042nd nationally
Madison Dam is a hydroelectric power plant in Montana with a nameplate capacity of 16.4 MW. It generates roughly 57.5k MWh per year — enough to power about 5,480 average U.S. homes.
Its capacity factor of 40% puts it in the middle range — running steadily but not full-time.
| Plant Name | Madison Dam |
|---|---|
| Operator | Northwestern Energy (Mt Hydro) |
| City | Ennis |
| County | Madison County |
| State | Montana |
| ZIP | 59729 |
| Coordinates | 45.48787, -111.63381 |
| ID | Technology | Fuel | Capacity | Status | Online |
|---|---|---|---|---|---|
| MAD5 | Conventional Hydroelectric | Water | 4.1 MW | Operating | 2021 |
| MAD6 | Conventional Hydroelectric | Water | 4.1 MW | Operating | 2021 |
| MAD7 | Conventional Hydroelectric | Water | 4.1 MW | Operating | 2022 |
| MAD8 | Conventional Hydroelectric | Water | 4.1 MW | Operating | 2022 |
| MAD1 | Conventional Hydroelectric | Water | 2.2 MW | Retired | 1906 |
| MAD2 | Conventional Hydroelectric | Water | 2.2 MW | Retired | 1906 |
| MAD3 | Conventional Hydroelectric | Water | 2.2 MW | Retired | 1906 |
| MAD4 | Conventional Hydroelectric | Water | 2.2 MW | Retired | 1908 |
| NERC Region | WECC |
|---|---|
| Balancing Authority | Northwestern Energy (Nwmt) |
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.