I have struggled with Muskrats in my 3 acre pond. I agree with Journeyman as above that a 110 conibear is a good choice to trap them. There are plenty of YouTube videos to describe how to use them. I ran into troubles when the rats got into my levee next to the outflow pipe. They burrowed in next to the pipe and then tunneled under it and then back along it for 4-5 feet. The concern for me was that water would start tracking along pipe and wash it out. I used sand bags and dammed up the area immediately in front of the pipe and then rented a small excavator and dug out the tunnels and dens and then filled it back in being careful to pack the soil back in tightly. Fortunately, they had not tunneled back as far as the first seep collar. Then I put a load of rip rap in the area. I used 6-8” rock and made sure it extended 4’ above and below the water line and 15-20 yards on each side. If the goal is prevention, then the best way to prevent problems is to rip rap wherever you feel like there is a vulnerable area. It was too expensive and labor intensive for me to rip rap my entire levee, so I only did the area that gave me the most heartburn for possible catastrophic failure. I now trap aggressively and pay close attention to the levee, watch for active runs and trap them ASAP. So far it is working.