Holter

Hydro power plant · Cascade County, Montana

Nameplate capacity
55 MW
Rank in Montana
#35
of 73 plants
In service since
2018
July 2018

Details

Primary fuel
Hydro
Technology
Conventional Hydroelectric
Operator
NorthWestern Energy (MT Hydro)
County
Cascade County
Generating units
4
Share of state capacity
0.71%
Rank among hydro plants in Montana
#13 of 23
EIA plant code
2186

Generating units

Individual generating units at Holter
UnitTechnologyNameplateSummerOnlineStatus
HOL1Conventional Hydroelectric15 MW15 MW2018Operating
HOL2Conventional Hydroelectric15 MW15 MW2018Operating
HOL3Conventional Hydroelectric15 MW15 MW2018Operating
HOL4Conventional Hydroelectric9.6 MW13 MW2018Out of service but expected to return to service in next calendar year

Nameplate is the maximum rated output; summer capacity is what the unit can reliably deliver on a hot day, which is typically lower.

Similarly sized plants in Montana

RyanHydro55 MW
Basin Creek PlantNatural gas55 MW
Colstrip Energy LPCoal46 MW
Spion Kop Wind FarmWind40 MW

About this data

From EIA’s inventory of operable generators, May 2026 release. Capacity is nameplate — the maximum rated output of the equipment, not what the plant actually generates over a year, which depends on how often it runs. A 55 MW solar plant and a 55 MW nuclear plant have the same entry here and produce very different amounts of electricity.

“In service since” is the earliest in-service date among the units still listed, so a site rebuilt around newer equipment can read as younger than the site itself. All Montana power plants · What Montana actually generates