How do I prevent snags while fishing for trout in a fast moving river?

I also fish for trout in a fast moving river. I use a Rapala F5 (floating). (It is probably about 20 or so feet across the river) Cast it to the other side. Let it float down river, but as it is going down river you want to keep throwing your line across too so it will follow the same path back. They usually sit on the sides of the bank in deep pools. Just reel it in slowly and the force of the moving water will make it vibrate and give the motion of a swimming bait fish. It will also sink a little even though it is a floating Rapala, but probably not to the point where you are getting snagged. There are a lot of good colors buy I usually have good lick with thte Clown and the Fire tiger. Good Luck!