The features shown in broken lines are environmental subject matter to the spa ledge with spill sill or portions of the spa ledge with spill sill forming no part of the claimed design. The features shown in long dash-short dash bolded broken lines indicate the bounds of the claimed design and otherwise form no part of the claimed design. None of the bottom surfaces of the spa ledge with spill sill are intended to be claimed, and therefore, the bottom view has been omitted from this application.