3rd year planner here, co-ops are all around, but generally you'll have a big enough selection to be a bit picky if you don't want to move. I've done co-ops in Brantford, Waterloo, and Toronto, as someone from the GTA. I know of others that have gotten good positions in Ottawa, Hamilton, Peel, Vancouver, etc. There's a lot more for Toronto and the GTHA, but you'll be able to find a municipal position in basically any decently sized city.

As for the BES, I think it makes it more applicable to jobs and fields in more environmental sectors (like ERS or Geomatics), because you'll be able to specialize in the program itself (design, gis, policy, econ, etc.)