Larry - a Conibear (killer) trap is relatively cheap, yet very effective for muskrats. You don't even need bait. Simply place the set trap underwater, in the path of an active shoreline slide. Place a branch over the top of the rectangular jaws to force the rat to pass through the trap. Size 110 should do a nice job on muskrats and other unwanted small rodents that set up shop in attics and barns.