My ex's uncle was the beaver guy for a small area of North Western Ontario. If they are a problem he would find their home (a mound of sticks surrounded by water). Paddle a small canoe out to it and land. At this point all the beavers that were home would run out and swim away. He would plant 2 or 3 sticks of dynamite with caps and wires attached and paddle back to the shore paying out the wire behind him. Then you wait about a hour so the beavers think everything is safe and go back into their house. Boom. No more beaver problems.
