A water distribution plate (22) and diffuser plate (50) assembly for distributing a stream emitted from a sprinkler nozzle comprising: a shaft (14) having one end attached to a sprinkler component and an opposite end supporting first and second plates in axially spaced relationship for rotation about the shaft independent of one another; the first plate located adjacent the nozzle (20) and formed with at least one water distribution groove (24) shaped and arranged to divide a primary stream emitted from the nozzle into a plurality of secondary streams, and the second plate located downstream of the first plate and formed with at least one diffuser element (54) arranged to be struck by at least some of the secondary streams exiting the first plate, and wherein speed of rotation of the first and second plates is braked.