What is an Integrated Resource Plan (IRP)?

Planning for reliable, affordable, sustainable energy over the next 20 years.

    What Is an Integrated Resource Plan (IRP)?

    A woman turns on lights in a kitchen

    What Is an Integrated Resource Plan (IRP)?

    An Integrated Resource Plan (IRP) is a long-term planning study that evaluates how NorthWestern Energy can meet customer electricity needs over the next 20 years under a variety of future scenarios while balancing reliability, affordability and risk. The IRP is not a construction plan or a final decision document. Instead, it establishes a transparent analysis of possible scenarios to guide future actions.

    To learn more about attending a public meeting or submitting written comments click the link below.

    Get involved! Download and read the 2026 Draft IRP

    What the IRP does:

    • Forecasts future electricity demand
    • Evaluates existing and potential energy resources
    • Test different future scenarios and risks

    What the IRP does not do:

    • Does not approve or build specific projects 
    • Does not set electric rates
    • Does not lock in a single path

    How is reliability defined?

    Reliability means having enough power plants and energy supplies available when customers need electricity, especially during winter peaks.

    NorthWestern plans for reliability using a regional program called the Western Resource Adequacy Program, or WRAP, which determines how much dependable generation capacity is needed to keep electricity shortages very rare – about one day in 10 years, on average.

    WRAP evaluates winter and summer separately and accounts for the fact that that generation resource production and loads are different during peak winter and summer conditions.  


    What inputs and assumptions go into an IRP?

    • Forecasts of future customer demand, including population growth, energy efficiency and net metering.
    • Assess existing generation, contracts, transmission and fuel systems.
    • Evaluates a broad range of capacity options such as natural gas, renewables and storage.
    • Tests multiple futures to understand cost, reliability and risk tradeoffs.

    What is being solved?

    Identifying the most cost-effective capacity to meet the reliability needs of customers, noting the cost of building new generation, potential risks and energy market forecasts.

     

    How reliable are we today?

    The Yellowstone County Generating Station on a cold, snowy day
    On Jan. 1, 2026, NorthWestern’s resource portfolio is adequate for the first time since serving Montana load. This was made possible by the new build of Yellowstone County Generating Station (YCGS), a 175-megawatt natural gas plant near Laural, Montana, and the acquisition of Avista’s 222-megawatt share of Colstrip. 

    Key findings:

    • The system meets reliability requirements today, but a winter capacity need begins to emerge around 2027–2028.

    • Early retirement of major resources such as Colstrip significantly increases customer costs.

    • Large customer growth can lower average energy costs but still requires new generation and transmission investments.


    What happens after the IRP?

    The IRP does not select a single resource today. Instead, it creates a foundation for future actions such as competitive resource solicitations and continued evaluation of emerging technologies.

     

    How to provide public comments on the Draft IRP:

    Electric Technical Advisory Committee

    The Electric Technical Advisory Committee, or ETAC, advises NorthWestern Energy in the preparation of its Resource Procurement Plan every three years. The primary goal of ETAC is to act as technical advisors through discussion, education, and collaboration on matters of future service and resources. The committee is tasked with strengthening NorthWestern’s resource planning efforts by providing insights and recommendations that take into account technical, economic and policy considerations.
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    Where does your energy come from?

    See, in real time, the resources being used to produce your electricity.
    View our hourly electrical generation by source