MT SB221

Requires mandatory greenhouse gas assessments under the Montana Environmental Policy Act (MEPA) for "fossil fuel activities" including coal mining, oil and natural gas drilling/production/compression, and burning fossil fuels for electricity generation

Allows but does not require greenhouse gas assessments for other proposed actions if the agency determines it necessary to meet MEPA requirements

Defines greenhouse gas emissions as carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride

Directs the Department of Environmental Quality to develop public guidance on methodologies for completing greenhouse gas assessments, with public notice and comment required before finalization

Explicitly states that greenhouse gas analysis is informational only and cannot be used to withhold, deny, or impose conditions on permits; agencies lack authority to regulate greenhouse gas emissions under MEPA