- Clean firm
- Operating
- 10 · 100 · 1,000 MW
Map
- Clean firm
- Operating
Madison Dam: location. Basemap: Protomaps, © OpenStreetMap contributors, ODbL.
Madison Dam
Power plant · Hydro
Key facts
Power plant · Hydroran 53% of 2025 Operating- Capacity
- Capacity: sourceEIA-860M · Open licenseMW
- Commissioned
- 2021
- Net generation, 2025
- 75,588 MWh
- Grid
- 100 kV to NorthWestern Energy LLC - (MT) (NWMT)
- Location
- Madison County, Montana
- Operated by
- NorthWestern Energy (MT Hydro)SourceEIA-860M Preliminary Monthly Electric Generator Inventory
Output
Details
Who’s behind it
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- Technology
- Hydro source: “Conventional Hydroelectric”
- Age
- 5 years since 2021
All 4 attributes from EIA-860M Preliminary Monthly Electric Generator Inventory
| Attribute | Value |
|---|---|
| Fuel burned (MMBtu), 2025 | 257,905 |
| Capacity factor, 2025 | 0.526 |
| Net generation (MWh), 2025 | 75,588 |
| Balancing authority code | NWMT |
Retirement
EIA-860M September 2026StatusSome generators have retired; the rest of the plant is still in service. As of EIA-860M for September 2026.- Capacity retired
- 8.8 MW
- Generators retired
- 4
- Capacity still in service
- 16.4 MW
| Generator | Technology | Nameplate | State | Date |
|---|---|---|---|---|
| MAD1 | Conventional Hydroelectric | 2.2 MW | Retired | October 2019 |
| MAD2 | Conventional Hydroelectric | 2.2 MW | Retired | October 2019 |
| MAD3 | Conventional Hydroelectric | 2.2 MW | Retired | October 2019 |
| MAD4 | Conventional Hydroelectric | 2.2 MW | Retired | October 2019 |
Grid
EIA-860 2025Grid fieldsAs the plant reported them to EIA-860 for 2025 (Schedule 2).- Grid voltage at the plant
- 100 kV
- Transmission or distribution system owner
- NorthWestern Energy LLC - (MT)
- Balancing authority
- NorthWestern Energy (NWMT)
- NERC region
- WECC
Can the connection be reused?
A plant that retires usually leaves its substation, transmission connection and interconnection agreement behind, and those may be reusable by a new project at the same site. FERC Order No. 845 lets an interconnection customer use surplus interconnection service at an existing site, and some transmission providers' tariffs let a replacement resource take over a retiring unit's interconnection service, usually within a set time after the retirement. Whether any such right still exists here, who holds it and on what terms depends on the owner, the transmission provider and timing; this page does not establish any of that.
Timeline
- In service · EIA-860M
- Stated Units MAD1, MAD2, MAD3, MAD4 scheduled to retire, 8.8 MW · EIA-860M
Sources
3 sourcesSources EIA-860M · EIA · EIA-860M Preliminary Monthly Electric Generator Inventory
Sources
- EIA-860M
- EIASource: U.S. Energy Information Administration, Electricity bulk data (Form EIA-923 monthly plant series)
- EIA-860M Preliminary Monthly Electric Generator Inventory