The pond I'm taking care of has had muskrat problems. They can tear up your smooth banks pretty good, and this can lead to lowering the water level of the pond if they dig in the right places. Luckily, although they have dug up the banks on ours, it hasn't caused water loss yet.

Another problem they caused us was chewing threw the windmill aerator's air hose under the water. I've already patched one hole and they've now chewed threw another spot. We've trapped about five or six last year and, judging by the tracks I've seen in the snow, there are at least two others living in it.

You never get over the problem since muskrat young will migrate from other ponds to new homes. Better off keeping at least two traps out all the time to catch the newcomers.