Plume is mitigated by targeting treatment chemicals to locations in a furnace, which are connected with plume opacity. The effectiveness of targeted in furnace injection, in fuel introduction and in furnace introduction of slag and/or corrosion and/or plume control chemicals are determined, as are the effectiveness of targeted in furnace injection, in fuel introduction and in furnace introduction of combustion catalysts. Then, the effectiveness of various combinations of the above treatments are determined, and a treatment regimen employing one or more of the above treatments is selected. Preferred treatment regimens will contain at least two and preferably three of the treatments. Chemical utilization and boiler maintenance can improved as LOI carbon, slagging and/or corrosion are also controlled.