VarmintSniper308,
My most productive muskrat set on a river is as follows. I find a large clump of grass and sod that has caved away from a high bank. An overhang will work too. There should be a least one foot of verticle bank exposed on the down stream edge or underneath the overhang. (I prefer a couple feet of water to stake in also) I build a level shelf about 3-4" deep with my boot to bed the trap on, usually a 1 1/2 CS or 1 longspring. Place the stake as far out in the river as you can. If the water is shallow place a tangle stick too. Next, I break an ear of corn in half and shove a stick into the center of the ear leaving about 8 inches protruding. I then stick the bait 4-6 inches, angled upward a bit, directly above the water line and over the bedded trap. Last, I splash water on the bait and near the set to help eliminate scent.
This is my favorite set and I've been hammering rats since 1980 with it. All the rivers I've trapped had corn near by but I bet corn will work anywhere. It's a great visual attractant.
Good luck,
Chris