There has been a lot of fuzz around the free entry to Ontario Parks, celebrating Canada’s 150th anniversary. Actually that is a initiative from Parks Canada, which is different from Ontario Parks.
Parks Canada is a national body that manages National Parks, National Marine Conservation Areas and National Historic Sites. E.g. Bruce Peninsula National Park, Banff, Jasper etc.
Whereas, Ontario Parks manages provincial parks within Ontario. E.g. Algonquin, Killarney etc.
The free Discovery pass 2017 is a initiative announced by Parks Canada, waiving the entrance/visitor fees to all of the parks and historic sites that come directly under its control. This does not apply to the parks governed by Ontario Parks. Ontario Parks as such has its own fees which are still very much applicable and you can find the details here https://www.ontarioparks.com/fees/dayuse/2017.
Also, note that the free Discovery Pass announced by Parks Canada applies only to the entrance fees. The camping fees, reservation fees and other fees are still applicable. You can find more details here https://www.pc.gc.ca/eng/voyage-travel/admission.aspx.
Hope this helps!
Patks Canada is offering the free passes- so not applicable at provincial parks. BUT great for entry to a lot of interesting places!!! Go online and request your pass!! While there, check put the list of places you can go!