BigOld- my pond is just year old and the muskrats hit me this sping. My brother in law was walking along and fell in a big sink hold and also saw what appeared a entry hole in the ground. Low and behold there were two of them and it took a bit of time but just waited in the truck with a refreshment and shot one with steel 2 shot and the other with 4 shot steel. Filled hole in and problems gone. Until next year that is as they will always show up according to other pond owners. Be diligent and keep up on them and good luck. happy hunting

jeff