Most graduate students (except in the M.Eng. program) have some degree of financial support, so you won't necessarily be adding to the debt you've accumulated doing your undergraduate degree. There are a number of means of financing your studies. They include scholarships, teaching assistantships and research assistantships. The number of major scholarships is limited. However, many graduate students get teaching and research assistantships. Students who are offered both teaching and research assistantships may expect to receive up to $15,000 or more per year.
The main graduate scholarships are:
Applications for all these must be submitted in early October, and the scholarships are awarded late March.
Many M.A.Sc. and Ph.D. students get TA's. These involve up to 10hrs work per week assisting a professor in a course by demonstrating labs, leading tutorials, and grading.
These are paid from the research funds of the supervising professor, and the amount depends on the professor and project.