Prevention of an accident is the best choice, If you look at a steep bank and say to yourself "that looks like a bitch" go with your first instinct. If you look at some tough wading and think that looks like a bit much, don't do it. A fish is not worth your life. However accidents do happen even in 2 feet of water like tripping and falling and breaking an arm. I carry a whistle, waste self inflating
belt and a personal electronic distress gadget, you pull the pin and it emits a sound for 12 hours like a smoke detecter. This thing is about the size of a pack of cigaretts. I always also use a wading staff no matter what the depth, it prevents tripping and makes a nice walking stick to and from the river. None of this stuff is a burden to carry and its there if you need it. The waste belt came in handy once, I was in 3' if water above a deep pool tripped and got swept in, shit happens in 3' feet of water.