Muskrats can cause serious damage when they burrow into pond embankments. They may also undermine retaining walls that shore up landscaping or homes. They burrow into these embankments to build their dens, but if the water level rises it can flood out the den. So the muskrat digs further back into the embankment or digs a new burrow with a higher den chamber closer to the surface. Over time, this burrowing activity weakens the structural integrity of the embankment, and it may fail.
Muskrats prefer to den about two feet from the water surface. By minimizing water level fluctuations, you can prevent muskrats from tunneling higher. Pond spillways should be regularly monitored to make sure the flow doesn’t get blocked by soil or debris. The water level should not fluctuate more than about six inches. A more expensive option is to install an embankment barrier.
Embankment barriers should be installed one foot above to three feet below the normal water level to prevent muskrats from burrowing. The barriers can be made of 1-inch mesh hardware cloth coated with rustproof paint or of aluminum or stainless steel mesh. Riprap is also effective if laid down at least six inches thick. Use rocks smaller than six inches in diameter to avoid creating cavities that will attract muskrats.