There's a lot more recent YA Canadian fantasy than there is science fiction. Oppel has another, The Live-Forever Machine, but it may be aimed at a younger audience than Dead Water Zone (I haven't read the former myself, so I'm not sure). There's Monica Hughes, of course, but that's not really recent -- Crisis On Conshelf Ten or the Isis books. Some reviews do call Margaret Buffie's The Watcher and The Seeker science fiction, though they seem more like fantasy to me; likewise Arthur Slade's Dust.
Any other recommendations?