Madison Dam

Madison Dam is a 16.4 MW operating hydroelectric plant in Madison County, Montana, operated by NorthWestern Energy (MT Hydro).

Plant statusOperating

Planning (completed)
Consented (completed)
Construction (completed)
OperatingSep 1906 (current stage)
ClosedOct 2019 (not yet reached)

This plant has generators at more than one stage; see the table below.

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Generators

Each generating unit EIA lists at this plant.

Unit	Technology	Capacity	Status	Online	Retired / planned retirement
MAD5	Conventional Hydroelectric	4.1 MW	Operating	Dec 2021
MAD6	Conventional Hydroelectric	4.1 MW	Operating	Dec 2021
MAD7	Conventional Hydroelectric	4.1 MW	Operating	Jan 2022
MAD8	Conventional Hydroelectric	4.1 MW	Operating	Mar 2022
MAD1	Conventional Hydroelectric	2.2 MW	Retired	Sep 1906	Oct 2019
MAD2	Conventional Hydroelectric	2.2 MW	Retired	Sep 1906	Oct 2019
MAD3	Conventional Hydroelectric	2.2 MW	Retired	Sep 1906	Oct 2019
MAD4	Conventional Hydroelectric	2.2 MW	Retired	Jul 1908	Oct 2019

Plant details

Operator: NorthWestern Energy (MT Hydro)
Location: Madison County, Montana
Balancing authority: NWMT
Sector: Electric Utility
Capacity: Operating: 16.4 MW
Retired: 8.8 MW
First unit online: Sep 1906
EIA plant ID: 6422

Location

45.4879, -111.6338

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Source: U.S. Energy Information Administration, Form EIA-860M, September 2026. Planned dates are targets reported by the developer and often change. Report a problem