PERI Greenhouse 100 Polluters State Press Release For Montana
November 6, 2025
With Future Data in Doubt, UMass Amherst Political Economy Research
Institute Names Top U.S. Climate Polluters
Rollback in EPA reporting requirements may end Greenhouse 100 Polluters
Index and access to vital public information
AMHERST, Mass. —
Researchers at the University of Massachusetts Amherst’s Political Economy Research Institute
(PERI) today published a new Greenhouse
100 Polluters Index, reporting 2023 greenhouse gas emissions using the
latest—and possibly last—data available from the U.S. Environmental Protection
Agency’s Greenhouse Gas Reporting Program.
On Sept. 12, the
EPA announced
plans to end most of the program and suspend all remaining reporting
requirements until 2034. The decision could leave the public without reliable,
standardized data on corporate climate pollution for nearly a decade.
“The Greenhouse
100 Index informs consumers, shareholders, regulators, lawmakers and
communities about corporate releases of climate-altering pollutants into our
environment,” says Professor Michael Ash, co-director
of PERI's Corporate Toxics Information Project. “The EPA’s decision to
effectively end the Greenhouse Gas Reporting Program removes access
to vital public information and leaves public and private decision-makers
flying in the dark or relying on a patchwork of voluntary and potentially
cherrypicked or greenwashed reports.”
Launched in 2018,
PERI’s free, open-access online tool provides data on every company that
reports to the EPA. The resource includes state-by-state
rankings and detailed reports identifying all companies and facilities
responsible for each state’s greenhouse gas emissions. Archives of earlier editions
remain available to the public.
The following is PERI's analysis for Montana.
Overall
| Summary for Montana | Value |
| Total 2023 CO2 equivalent emissions (millions of metric tons): | 18.1 |
| Percentage of national total: | 0.7 |
| Rank among US states (1=top): | 37 |
Top 5 Polluter Companies in Montana
Top 5 Sectors in Montana
| Sector Name | CO2 equivalent emissions (mmt) | Num. facilities |
| Power Plants | 13.5 | 8 |
| Petroleum Refineries | 2.0 | 4 |
| Hydrogen Production | 1.1 | 4 |
| Cement Production | 0.6 | 2 |
| Lime Manufacturing | 0.4 | 2 |
Top 10 facilities in Montana
| Facility Name | CO2 (metric tons) | Company |
| Colstrip | 10,967,111 | Colstrip Power Plant (single power plant) |
| PHILLIPS 66 BILLINGS REFINERY | 967,045 | Phillips 66 |
| CHS INC LAUREL REFINERY | 918,021 | CHS Inc. |
| YELLOWSTONE ENERGY LIMITED PARTNERSHIP | 830,005 | Par Pacific Holdings |
| Par Montana, LLC Billings Refinery | 719,769 | Par Pacific Holdings |
| Hardin Generating Station | 663,072 | Blackstone |
| COLSTRIP ENERGY LTD PARTNERSHIP | 474,565 | Colstrip Energy |
| Calumet Montana Refining, LLC | 427,371 | Calumet Specialty Products |
| Dave Gates Generating Station | 330,090 | NorthWestern Corp. |
| ASH GROVE CEMENT COMPANY-MONTANA CITY | 323,958 | CRH PLC |
“In making this
information available, we are building on the historic achievements of the
right-to-know movement,” Ash adds. “Our goal is to engender public
participation in environmental decision-making, and to help residents translate
the right to know into the right to clean air, clean water and a livable
planet.”
The EPA’s
rollback of reporting and disclosure requirements also threatens other PERI
indexes that track companies’ release of pollution into the air and water, and
near schools.
Contacts:
Michael Ash, mash@umass.edu
Aaron Kupec, akupec@umass.edu
|
Political Economy Research Institute