A system includes a plurality of interconnected mixing assemblies configured to mix a first fuel and water to generate a first mixture, and mix a second fuel and the water to generate a second mixture. The first and second fuel mixtures are configured to combust in a plurality of combustors of a gas turbine. The interconnected mixing assemblies include first and second fuel passages, a water passage, first and second mixers, first and second fuel valves, and first and second water valves disposed in an integrated housing. The first fuel valve has a first fuel flow coefficient between approximately 1.0 to 1.5, the second fuel valve has a second fuel flow coefficient between approximately 3.0 to 5.0, the first water valve has a first water flow coefficient between approximately 0.4 to 0.55, and the second water valve has a second water flow coefficient between approximately 3.5 to 5.0.