The report gives methods and results of an environmental assessment test program at Pacific Gas and Electric's Moss Landing Power Plant, Unit 6. The aim of the program was to measure changes in emissions as a result of applying NOx controls. Emissions of trace elements, organic materials, sulfur species, particulate matter, CO2, O2, NOx, and CO were measured. These emissions, under as-designed and controlled (for NOx) operating conditions, were compared. Source operating data were also analyzed so that changes in operating parameters and efficiency could be assessed. Two degrees of NOx control were tested: the highest level, corresponding to present boiler operation, consisted of burners-out-of-service and flue gas recirculation (FGR) to the windbox; and the other, representing an intermediate degree of control, consisted of only FGR to the windbox.