I'm very happy that you can get Roundup again in Ontario. I use it in a very green manner. You don't want it to get into the water, so you only use it on dry days. In a few hours, it binds to organic matter, and can't move. In a week the little soil bacteria eat it up.
Now, I'm using it to nuke any bad grass. Without Agent Orange available, the grass has been getting full of all sorts of nasty creepers, as well as huge lumps of quackgrass. I spray it, wait a week or two and spray it again. After another week or two, when I'm sure everything is dead, I loosen up the soil with a pitchfork and seed it. Right now my seed is coming up beautiful! You can seed right through the dead straw, which provides some protection, and you have to water every day.