The decision of where to send your child to school is a big one. Obviously the neighborhood that you live in, and the programs your child participates in, influence your decision; but this site might help if you're planning on moving or putting your child into a magnet school.
The Fraser Institute has a website that shows the rankings of Alberta's schools. I noticed that it's missing some Medicine Hat schools, but it at least gives you an idea of some of the local schools.
In fairness I have to point out that many educators and administrators feel that school rankings are misleading and misinterpreted. And I agree that academic ranking is not the only benchmark for a school.
My own perspective is that there are elements that go into the overall education and development of a child that have little to do with academic scores; such as: religious instruction, healthy social interactions, music and the arts, and contribution to the community, etc. Therefore, your decision can't simply be based on Provincial Achievement Test scores. It is possible to have a child graduate with straight A's, but be completely morally bankrupt. You have to evaluate all aspects, not just the academic, before making your decision.
UPDATE: One of my Facebook friends directed me to the Province's Accountability Pillar Report for the overview summary of the province's education assessment.