Madison Dam
Madison County, Montana · EIA plant ID 6422 · Operator: NorthWestern Energy
Nameplate16MWSummer 16 MW
Generators4in service
Net generation76GWh12 mo to Dec 2025
Capacity factor53%hydro units, summer MW
Heat rate—thermal plants only
First online2021
Monthly net generation
EIA-923, all units at the plant. Net of station use; storage can go negative.
FinalPreliminary
Capacity factor by year
Net MWh ÷ (summer MW × hours), hydro units. Each year uses that year's EIA-860 ratings; the hollow dot is the latest 12 months.
Heat rate by year
Electric fuel MMBtu × 1000 ÷ net MWh (Btu/kWh, HHV), fossil units only; CT + CA counted as one combined-cycle block.
Heat rate applies to fuel-burning (thermal) units only.
Annual data table
| Year | Net GWh | Capacity factor | Heat rate (Btu/kWh) |
|---|---|---|---|
| 2001 | 62.4 | 85.2% | — |
| 2002 | 58.8 | 74.5% | — |
| 2003 | 60.1 | 77.9% | — |
| 2004 | 61.3 | 79.2% | — |
| 2005 | 65.8 | 85.3% | — |
| 2006 | 67.6 | 87.7% | — |
| 2007 | 60.1 | 78.0% | — |
| 2008 | 57.1 | 73.8% | — |
| 2009 | 62.5 | 89.1% | — |
| 2010 | 61.7 | 88.1% | — |
| 2011 | 65.1 | 92.9% | — |
| 2012 | 66.4 | 94.5% | — |
| 2013 | 56.5 | 80.6% | — |
| 2014 | 53.6 | 76.5% | — |
| 2015 | 59.4 | 84.8% | — |
| 2016 | 57.1 | 81.3% | — |
| 2017 | 62.3 | 88.9% | — |
| 2018 | 62.6 | 89.3% | — |
| 2019 | 51.3 | 73.2% | — |
| 2020 | 0 | 0.0% | — |
| 2021 | 1.1 | 1.1% | — |
| 2022 | 65.4 | 47.4% | — |
| 2023 | 57.5 | 40.1% | — |
| 2024 | 76.2 | 52.9% | — |
| 2025 | 75.6 | 52.6% | — |
Generators
EIA-860 (annual) with EIA-860M updates through Sep 2026. EIA-923 reports generation by plant, prime mover and fuel, not by unit, so unit-level output isn't shown.
| Gen ID | Technology | Prime mover | Nameplate MW | Summer MW | Online | Status | Planned retirement | OEM / model |
|---|---|---|---|---|---|---|---|---|
| MAD5 | Conventional Hydroelectric | HY | 4.1 | 4.1 | Dec 2021 | Operating | — | coming soon |
| MAD6 | Conventional Hydroelectric | HY | 4.1 | 4.1 | Dec 2021 | Operating | — | coming soon |
| MAD7 | Conventional Hydroelectric | HY | 4.1 | 4.1 | Jan 2022 | Operating | — | coming soon |
| MAD8 | Conventional Hydroelectric | HY | 4.1 | 4.1 | Mar 2022 | Operating | — | coming soon |
| MAD1 | Conventional Hydroelectric | HY | 2.2 | 3.7 | Sep 1906 | Retired Oct 2019 | — | coming soon |
| MAD2 | Conventional Hydroelectric | HY | 2.2 | 3.7 | Sep 1906 | Retired Oct 2019 | — | coming soon |
| MAD3 | Conventional Hydroelectric | HY | 2.2 | 3.7 | Sep 1906 | Retired Oct 2019 | — | coming soon |
| MAD4 | Conventional Hydroelectric | HY | 2.2 | 3.7 | Jul 1908 | Retired Oct 2019 | — | coming soon |
Owner / operator
Operator: NorthWestern Energy. Ownership shares by in-service nameplate MW (EIA-860 Schedule 4; units not listed there are wholly owned by the operator).
| NorthWestern Energy | 100.0% | 16 MW |
Nearby plants
Within 80 km.
| GCC Trident Solar Project | 4 MW | 51.7 km |
| Broadwater Power Project | 10 MW | 72.5 km |