muskrats!

I had a muskrat problem years ago. He destroyed the stone path around
the pond by digging underneath it, then dug trenches into the lawn. I
tried trapping the beast to no avail. After reading about their
habitat, I drained the pond, removed most of the vegetation, and most
importantly removed the island in the middle of the pond (that was
where the muskrat had his home). Refilled the pond and no more
muskrat! We have hawks in the area that like to hunt muskrats.