A gas turbine engine including a compressor section and a turbine section, coupled by one or more shafts, is provided. The compressor section progressively compresses air and includes an aft-stage of rotor blades rotatable about an axial direction of the gas turbine engine. A cooling system is included with the gas turbine engine for cooling compressed air in or from the compressor section. The cooling system includes a fluid tank for storing a volume of cooling fluid and one or more fluid lines in fluid communication with the fluid tank. The one or more fluid lines include an outlet positioned adjacent to the aft-stage of rotor blades for injecting cooling fluid into the compressed air proximate the aft-stage of rotor blades.