Colstrip Generating Plant
NorthWestern Energy will acquire Avista’s 222-megawatt ownership of Colstrip Units 3 & 4 in 2026.
Electric Generation
At NorthWestern Energy, our goal is to provide our customers reliable energy at the lowest long-term cost. We do this through a balanced mix of safe, reliable, affordable and clean energy.
Reliable energy when Montana needed it most
Montanans relied heavily on electricity during July's extreme heat, when temperatures topped 100 degrees across much of the state and reached a record 111 degrees in Billings on July 12, 2026. Throughout the heat wave, NorthWestern Energy's balanced, resource adequate electric generation portfolio and transmission system provided reliable service to customers across Montana.
On July 24, 2026, demand for electricity within the NorthWestern Energy-managed portion of Montana's electric grid reached a summer record peak of 2,045 megawatts. NorthWestern Energy met that demand without interruption, supported by a combination power generation resources and a robust transmission network.
The acquisition of an additional share of the Colstrip Plant on Jan. 1, 2026 marked an important milestone for NorthWestern Energy in Montana. For the first time in decades, our Montana generation portfolio is resource adequate to meet our customers' energy needs when they need it most thanks to Montana-based and Montana-dedicated resources.
Our balanced portfolio includes carbon-free hydro, wind and solar resources, complemented by 24/7 on-demand generation, including the Colstrip Plant and Yellowstone County Generating Station. Together these resources and our robust transmission system ensure reliable energy is available for our Montana customers in every season and all weather conditions.
When extreme heat drives up energy use, our customers need to know they can count on us. Whether it's keeping homes cool, powering businesses or supporting essential services, our job is to deliver reliable energy 365 days a year around the clock.
That's what guides our planning and investments every day. At NorthWestern Energy, our customers come first. We're committed to providing the dependable energy service Montana families, businesses and communities rely on, no matter what the weather brings.
Electric Generation
This chart shows in near real time where your energy is coming from, with the red line showing the forecast of how much electricity we need to generate to meet demand.
When generation doesn't meet demand (when there is a gap between the colored bars and the red line), we buy additional electricity from the open market. When generation exceeds demand (the colored bars go above the red line), we can sell the extra energy on the market.
- Our hydro resources (light blue) are the base of our electric generation in Montana. The amount of electricity generated by our hydro facilities is fairly consistent.
- Wind resources (light green) vary dramatically. When the wind is blowing, our production generally exceeds our demand.
- We rely on thermal resources (dark blue) to ramp up and help meet demand when the wind isn't blowing, and the sun isn't shining.
Hourly electrical generation by source (Montana)
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Hydropower
35% of our electricity for our Montana customers comes from 100% clean hydroelectricity.
Yellowstone County Generating Station
The Yellowstone County Generating Station will provide on‑demand resources to support the variability of wind and solar projects coming onto our system and help serve our customers during extended periods of peak demand.
Our Balanced and Diverse Energy Mix
At NorthWestern Energy, our goal is to provide our customers reliable energy at the lowest long-term cost. We do this through a balanced mix of safe, reliable, affordable and clean energy. Our electric portfolio is built on the carbon-free hydro system, along with wind, coal, gas and solar.
Our Bob Glanzer Generating Station
Our Bob Glanzer Generating Station
The 58-megawatt Bob Glanzer Generating Station in Huron, South Dakota, provides on‑demand resources to support the variability of wind and solar projects coming onto our system and help serve our customers during extended periods of peak demand.
Our Commitment to Clean Energy
At NorthWestern, we understand that almost everything we do to produce and deliver energy to our customers impacts the environment. We are committed to providing cost-effective, reliable and stably priced energy while being good stewards of natural resources.
Innovating Our Energy Future
We are committed to providing responsible, sustainable energy to meet our customers' needs, while protecting, and even enhancing, the natural environment. And we are always looking for ways to improve the way we generate energy and serve our customers.