Montana concluded its 69^th legislative session on April 30, 2025. Convening only every other year for 90 days, the state’s 150 legislators work to pass bills and to develop a biennial budget building on Governor Greg Gianforte’s proposed budget priorities. Of the 1,759 bills introduced this session, 884 passed. As of June 25, Governor Gianforte had signed 817 of those bills into law and vetoed 32.

The Clean Energy Transition Institute (CETI) tracked bills related to the clean energy transition and climate change. While several pieces of legislations were introduced that would have inhibited clean energy development in the state, many of the most restrictive bills did not make it over the finish line and several measures meant to promote transmission expansion did. Below is a recap of some key bills that passed and failed:

What Passed

• SB 301 – Amends laws governing utility lines and facilities, including by granting the Public Service Commission the ability to provide public utilities with a Certificate of Public Convenience and Necessity for the construction of electric transmission facilities. The bill also highlights the importance of advanced transmission technology for reduced fire risk and increased capacity, efficiency, and reliability.
• HB 424 – Revises the classification and taxation of class 17 data center properties. Changes include an extension of the timeframe in which a data center property must be built, certain mandates for the payment of school equalization mills (a property tax rate levied to fund schools) by data center properties, and other criteria relating to the generation and sale of power by these properties.
• HB 490 – Requires electric facilities to prepare and implement Wildfire Mitigation Plans (WMP) that must meet certain requirements and be updated every three years. The bill also affords those utilities that have followed an approved WMP certain civil liberty protections in the event of injury or damages from a wildfire.
• HB 939 – Stipulates that a wind turbine may not be constructed if it is 500 feet or more in height or if it is located less than 1,500 feet from an occupied residence, unless a shorter setback is approved by the property owner. The bill also includes updated requirements for wind turbine generator deicing to ensure that commercially reasonable efforts are made to mitigate icing risks. ‍
• HJ 15 – Joint resolution by both chambers supporting increased transmission capacity in Montana by upgrading and expanding electric transmission infrastructure within the state and on pathways across state borders to ensure affordable and reliable electricity service. The bill emphasizes that enhancing transmission infrastructure is crucial for economic growth, cost savings, energy reliability, and maximizing the state’s energy development potential. The bill also points to reconductoring with higher-capacity lines and other modern technologies as a lower-cost strategy to achieve those benefits. Additionally, the legislation prioritizes skilled Montana-based labor to make transmission improvements.‍
• SJ 12 – Joint resolution by both chambers requesting an interim study on electric transmission capacity to analyze the economic impact on Montanans and industry due to congestion and curtailments on certain transmission pathways. The bill emphasizes Montana’s potential to produce renewable energy to meet increasing demand for cleaner energy and calls for the designation of a committee to investigate economic implications of congestion and curtailments, available transmission capacity, and upgrades needed to ensure affordable and reliable electricity. ‍
• SJ 21 – Joint resolution by both chambers requesting an interim study on the development of an interstate power grid. The resolution points to the need for the expansion and modernization of Montana’s electric transmission infrastructure to ensure reliable and affordable energy. It also acknowledges restrictive policies in certain jurisdictions that hinder needed transmission projects and increase costs for ratepayers.

What Failed

• SB 160 – Would have revised alternative energy project laws to require a bond prior to construction.
• SB 283 – Would have generally revised laws relating to wind generation facilities.
• SB 505 – Would have generally revised zoning laws to prohibit the construction of wind generation facilities.
• HB 314 – Would have established a Montana Energy Authority to oversee energy generation and electric transmission development in the state.
• HB 326 – Would have increased taxes on non-coal electrical energy to match the coal severance tax rate.
• HB 389 – Would have required setbacks for wind turbine generators.
• HB 877 – Would have established the Montana Data Center Development Act to create a stable and predictable regulatory environment for large electricity consumers.
• HB 915 – Would have revised taxation of certain wind generation facilities.
  

Major Setback for MEPA

In 2024, the youth-led Held v. Montana case became the first climate-related constitutional lawsuit to go to trial in the United States. It challenged aspects of Montana’s State Energy Policy Act and the Montana Environmental Policy Act (MEPA) as unconstitutional on the basis that they violated students’ constitutional right to a clean and stable environment by limiting the analysis of greenhouse gas emissions during the environmental review process.

The Montana Legislature passed a suite of new bills that the Governor signed into law this year to amend MEPA – an act dating back over 50 years that requires environmental review of Montana’s government projects – to counter the Montana Supreme Court ruling. The bills included:

• HB 270 – Amends MEPA to revise the environmental review process conducted by state agencies. Revisions include the removal of a provision that allowed state agencies to exercise regulatory authority beyond existing statutes and specifies that greenhouse gas emissions will not be evaluated in environmental reviews unless done jointly with a federal agency or if federal law changes. It also establishes stricter criteria for judicial challenges.
• HB 285  – Clarifies that MEPA is purely procedural in nature and is not a meant to provide additional regulatory authority to a state agency. The bill also strikes existing language directing agencies to consider and take appropriate action to prevent long-range environmental impacts that would result in a decline in Montana’s environment.
• HB 291 – Revises the Clean Air Act of Montana to prevent the state from adopting air pollutant standards more stringent than those of the federal government.
• HB 466 – Introduces the concept of ‘categorical exclusions’ – state actions for which an environmental assessment or impact assessment are not required. These include exemptions to the Department of Administration for construction and maintenance on state land, as well as to the Department of Commerce for historic preservation grants.
• SB 221 – Revises remedy requirements of MEPA related to the environmental review process. While identifying six greenhouse gases that the state must inventory when doing environmental reviews of energy projects, it directs agencies like the Montana Department of Environmental Quality not to regulate them.

A Veto for Shared Solar

Known as the ‘Montana Solar Shares Act,’ SB 188 would have established a framework for shared solar facilities in Montana. Among other provisions, it distinguished between shared solar customers and net-metering customers and included requirements for public utilities to interconnect shared solar facilities to their distribution systems.

The bill also mandated that shared solar facilities have a generating capacity between 50 kilowatts and 5 megawatts and that they provide on-bill credits to subscribers. Overall, this bill was meant to enable shared solar energy development across the state while ensuring reliable and equitable access for all customers.

Solar share programs such as the one outlined in this bill, often referred to as ‘community solar,’ allow multiple households to receive the benefits of solar energy, without having to install panels on their roofs, by buying or leasing part of a larger solar array in their community.

Benefits can include increased energy resilience, wider access to solar for more diverse customer classes, reduced electricity costs, income generation, and local job creation. The National Renewable Energy Laboratory has a database of known community solar projects in the country (Figure 1), which indicates that 44 states (including Montana) and the District of Columbia are home to community solar projects and that 24 states and the District of Columbia have policies that specifically support community solar projects, the majority of which include provisions for low- and moderate-income households.

Montana’s Solar Shares Act passed the Montana State Legislature with broad bipartisan support at the end of April 2025. It was signed by the Speaker of the House and President of the Senate and transmitted to the Governor for final signing. However, the bill faced strong opposition from some of the state’s investor-owned utilities, and on June 9, 2025, Governor Gianforte vetoed it.

Given the number of votes the bill garnered in the House and Senate, the possibility remains that the Legislature will override the veto. There is also the chance of developing a regulatory pathway to accomplish the intent of the legislation. If neither of these options pan out, it will be two years before the Solar Shares Act gets another chance at becoming law in Montana, when the Legislature convenes again in 2027.

For a recap of what climate and clean energy bills passed in other Northwest legislative sessions in 2025, check out our overviews of Idaho and Washington. The Oregon legislative session will conclude at the end of June and a recap of that session will be available soon after. If you want to receive updates from CETI straight to your inbox, subscribe here.