For an electric utility in the western US, Brattle experts conducted a study to assess reliability and supply-chain implications of compliance with the EPA’s Regional Haze Rule. The Regional Haze Rule aims to reduce haze-forming pollution (primarily due to emissions of particulate matter and its precursors SO2 and NOX) that reduces visibility in parks and wilderness areas, especially in the Western US. We assessed the impact of outages at coal units to tie-in the environmental retrofit equipment on available resources to meet the utility’s load obligations in the future. In addition, we compared the historical retrofits on coal units in the region against projected retrofits to comply with the Regional Haze Rule.