Holter
Cascade County, Montana · EIA plant ID 2186 · Operator: NorthWestern Energy
Nameplate55MWSummer 57 MW
Generators4in service
Net generation248GWh12 mo to Dec 2025
Capacity factor50%hydro units, summer MW
Heat rate—thermal plants only
First online1918
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 | 201.6 | 63.1% | — |
| 2002 | 199.9 | 47.5% | — |
| 2003 | 250.8 | 74.5% | — |
| 2004 | 207.1 | 61.4% | — |
| 2005 | 251.4 | 74.7% | — |
| 2006 | 279.7 | 83.1% | — |
| 2007 | 223.2 | 66.4% | — |
| 2008 | 267.5 | 63.4% | — |
| 2009 | 319.8 | 76.1% | — |
| 2010 | 303.9 | 72.3% | — |
| 2011 | 348.3 | 82.8% | — |
| 2012 | 283.2 | 67.2% | — |
| 2013 | 226.3 | 53.8% | — |
| 2014 | 249.6 | 59.4% | — |
| 2015 | 258.6 | 61.5% | — |
| 2016 | 254.1 | 60.3% | — |
| 2017 | 299.9 | 71.3% | — |
| 2018 | 341.8 | 73.3% | — |
| 2019 | 344.9 | 74.0% | — |
| 2020 | 298.2 | 63.8% | — |
| 2021 | 200.7 | 43.1% | — |
| 2022 | 225.8 | 49.7% | — |
| 2023 | 281.6 | 61.9% | — |
| 2024 | 265.8 | 52.0% | — |
| 2025 | 247.5 | 48.6% | — |
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 |
|---|---|---|---|---|---|---|---|---|
| HOL1 | Conventional Hydroelectric | HY | 15 | 15 | Jul 1918 | Operating | — | coming soon |
| HOL2 | Conventional Hydroelectric | HY | 15 | 15 | Jul 1918 | Operating | — | coming soon |
| HOL3 | Conventional Hydroelectric | HY | 15 | 15 | Jul 1918 | Operating | — | coming soon |
| HOL4 | Conventional Hydroelectric | HY | 9.6 | 12 | Jul 1918 | Operating (Out of service, expected back within the year) | — | 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% | 55 MW |
Nearby plants
Within 80 km.
| Hauser | 17 MW | 26.6 km |
| Great Divide Solar, LLC | 3 MW | 27.8 km |
| Green Meadow Solar, LLC | 3 MW | 33.3 km |
| Canyon Ferry | 58 MW | 43.5 km |
| Turnbull Hydro | 13 MW | 68.6 km |
| Horseshoe Bend Wind Park | 10 MW | 70.7 km |