First, determine if muskrats live in your part of the country. If they do, then it is possible that the damage you see, primarily burrowing activity, was caused by muskrats. Burrowing may not be readily evident until serious damage has occurred.
One way to observe early burrowing in farm ponds or reservoirs is to walk along the edge of the dam or shorelines when the water is clear and look for “runs” or trails from just below the normal water surface to as deep as 3 feet (91 cm). If no burrow entrances are observed, look for droppings along the bank or on logs or structures that a muskrat can easily climb up on. If the pond can be drawn down from 1 1/2 to 3 feet (46 to 91 cm) during winter, muskrat burrows will be exposed, just as they would during extended periods of drought.
Any burrows discovered in the dam should be filled, tamped in, and covered with rock to avoid possible washout or, if livestock are using the pond, to prevent leg or foot injuries.
Where damage occurs to a crop, plant cutting is usually evident. Aquaculture impoundments are generally maintained without extensive aquatic vegetation. In these situations, look for muskrat runs and burrows or the easily observed remains of mussels, crayfish, or fish along with other muskrat signs (tracks or droppings).
Resources: (online)
Muskrats
