Data last collected:
PowerPlantFactsEvidence report · prepared 19 October 2026https://powerplantfacts.com/entity/6422
EIA plant 6422
Ennis · Madison · MT
Madison Dam
Operated by NorthWestern Energy (MT Hydro)
Published location
Where is Madison Dam?
This locator uses the coordinates in the approved source record. It shows geographic context, not a site boundary, safety zone or property-risk area.
45.487869, -111.633807
Open the interactive map ↗Map data © OpenStreetMap contributors
Capacity is not generation. Nameplate MW describes equipment; annual MWh describes recorded output. Proposed and retired units are not added to operating capacity.
Equipment mix
Operating capacity by technology
Grouped from this plant’s represented generator records. Use the MT plant index for regional peers.
See the evidence
Electricity output across the year
Monthly net generation shows the seasonal shape of this plant's represented output. A negative value is retained when the source reports net consumption.
13,956
26,162
36,628
46,235
57,753
67,501
76,842
86,563
95,884
106,282
115,542
126,861
MWh net generation · 2024 final edition · EIA 923 represented operating rows. 12 of 12 supplied rows shown; 0 missing values omitted. Months with no reported numeric value are omitted, not treated as zero.
Read the chart as a table
| Record | MWh net generation |
|---|---|
| 1 | 3,956 |
| 2 | 6,162 |
| 3 | 6,628 |
| 4 | 6,235 |
| 5 | 7,753 |
| 6 | 7,501 |
| 7 | 6,842 |
| 8 | 6,563 |
| 9 | 5,884 |
| 10 | 6,282 |
| 11 | 5,542 |
| 12 | 6,861 |
2024 monthly net generation
| Month | Net generation |
|---|---|
| 1 | 3,956 MWh |
| 2 | 6,162 MWh |
| 3 | 6,628 MWh |
| 4 | 6,235 MWh |
| 5 | 7,753 MWh |
| 6 | 7,501 MWh |
| 7 | 6,842 MWh |
| 8 | 6,563 MWh |
| 9 | 5,884 MWh |
| 10 | 6,282 MWh |
| 11 | 5,542 MWh |
| 12 | 6,861 MWh |
Operating generators
| ID | Technology | Fuel | MW | Status |
|---|---|---|---|---|
| MAD5 | Conventional Hydroelectric | WAT | 4.1 | OP |
| MAD6 | Conventional Hydroelectric | WAT | 4.1 | OP |
| MAD7 | Conventional Hydroelectric | WAT | 4.1 | OP |
| MAD8 | Conventional Hydroelectric | WAT | 4.1 | OP |
Continue exploring
Similar-capacity plants in the same state
Identity, technology and limitations
EIA plant ID
6422
Sector
Electric Utility
Water source
Madison River
Data edition
2024-final
Use this record
Questions this evidence can answer
01What exactly is this record?
Use the name, place, date and identifiers above to confirm that you have the right Madison Dam power plant: capacity and generation | PowerPlantFacts record.
02What does the evidence establish?
Read the reported values with their units, coverage dates and source notes. Keep observed facts separate from estimates or interpretation.
03What should I verify next?
Follow the primary-source links and check the limitations before using this evidence for a decision, comparison or citation.
A closer look at Madison Dam
Variation in the published months
Across 12 numeric monthly generation entries, 5 has the highest recorded value (7,753 MWh) and 1 the lowest (3,956 MWh). Their difference is 3,797 MWh. Missing months have not been treated as zero.
Generator capacity in different operating conditions
| Generator ID | Technology | Nameplate MW | Summer MW | Winter MW | Minimum load MW |
|---|---|---|---|---|---|
| MAD5 | Conventional Hydroelectric | 4.1 | 4.1 | 4.1 | 0.5 |
| MAD6 | Conventional Hydroelectric | 4.1 | 4.1 | 4.1 | 0.5 |
| MAD7 | Conventional Hydroelectric | 4.1 | 4.1 | 4.1 | 0.5 |
| MAD8 | Conventional Hydroelectric | 4.1 | 4.1 | 4.1 | 0.5 |
EIA-860 2024 final source. Ratings describe capacity, not actual generation or availability. Missing ratings are not zero.
Source: US Energy Information Administration Form EIA-860 2024 plant and operable-generator workbooks; archive 2024. US EIA-authored information is generally public domain; cite EIA, preserve third-party exceptions, changes and no-endorsement context. Source-specific derived data.