The ornamental design for a hydraulic dischargesystem, as shown and described.
FIG. 1 is a front left perspective view of a hydraulic discharge system showing my design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a right side view thereof; and,
FIG. 7 is a left side view thereof.
Internal components and certain external features of the hydraulic discharge system are shown in broken lines for illustrative purposes and form no part of the claimed design.