A heat recovery steam generator (HRSG) is coupled to a gas turbine engine that discharges a flow of exhaust gases including oxides of nitrogen (NOx) The HRSG includes a steam-based heating element for heating the exhaust gases, and at least one NOx reduction element coupled downstream from the at least one steam-based heating element and configured to facilitate reducing an amount of NOx in the exhaust gases that are channeled into the at least one NOx reduction element.