Trying to think of any stations around here that do not have diesel. Between farm and oil industry pickups they make up a sizeable chunk of the vehicles on the road. And although farm trucks usually fill up at home with purple they still need to be able to get diesel when they are towing their trailers on a holiday or to a rodeo.
At most stations they are at the same pump, the bright yellow nozzle is for diesel and the other for the rest of us. I would not worry about getting diesel in Alberta.