you can check www.ontariobadminton.on.ca they have quite a list of events in their events calendar.... however, the season is nearly over... you may be a tad late... but i could be wrong... check the calendar!
There will be tournament in June hosted by the Mississauga Chinese Professionals and Businesses (CPB) association in Mississauga. There will be more information on the OBA website for that as well in the near future. It's an open tournament that should attract quite a lot of players.