Felipe Miranda of Chile won gold, while Argentina's Julio Javier earned bronze.
Llewellyn, from Innisfail, Alta., lost to Miranda by just 20.5 points.
Earlier, Canadian Whitney McClintock won gold in the women's water-skiing competition.
The Cambridge, Ont., native finished ahead of American Regina Jaquess and Mexico's Carolina Chapoy.
McClintock took the lead in the overall performance after earning 8370 points in the tricks event.