The Boise river, like most in Idhao has a lot of diversion dams, otherwise known as mankillers. You really need to stay away from diversions and the tree snags that can flip a lig jet boat in a hurry let alone a canoe. there's other junk out ther too--fence post sna old wire, that make it really dangerous.
You should canoe the rive during warm weather before going out in cold weather. you are likel to lose guns and equipment, but hopefully not your life. That said, water moving at 3 or 4 mph will put about 200 pounds of force on your body, making it hard to get free once you're pinned against an underwater rock or tree, or your foot becomes tangled in old fence. This is how people die.
What's so funny 'bout peace love and understanding?