The ornamental design for a cell for a watermanagement system, as shown and described.
FIG. 1 is a right-front perspective view of a cell for a water management system showing the new design;
FIG. 2 is a top view thereof;
FIG. 3 is a bottom view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a right elevation view thereof;
FIG. 6 is a rear elevation view thereof;
FIG. 7 is a left elevation view thereof; and,
FIG. 8 is right-front perspective view thereof showing environment.
The broken lines immediately adjacent the shaded areas represent the bounds of the claimed design while all other broken lines are directed to environment; broken lines form no part of the claimed design.