Waterscapes 101

How to Repair Muskrat Holes on Pond Dams

Muskrats are one of the most damaging animals to a pond.  Muskrats can quickly threaten the integrity of a pond dam since they burrow at the water surface and build tunnels that connect to larger spaces.  In many cases, muskrat damage can be minimized if the tunnels and associated dam leaks are repaired quickly. A muskrat burrow can quickly cause catastrophic failure of a pond or lake dam if the tunnels go unnoticed and a heavy rainfall occurs.  Extensive erosion can start at the muskrat hole and quickly eat in to the dam. 

Best practices for any dam are to incorporate regular inspections so that damage can quickly be repaired.  Once muskrat damage is identified, it is best to remove the culprits from the local area.  Then, quickly proceed with repairs so that the damage doesn’t worsen. 

How can muskrat holes be fixed?  Depending on the local conditions and the age of the tunnels, the repairs can generally be made by hand.  Simply open the burrows with a shovel to expose them.  They will likely be very shallow and may actually collapse when stepped on.  Take care to clean out any areas that have collapsed so that you are working with solid soil.  (We recommend opening at least 8 feet of tunnel starting closest to the water for repairs)  It is a good practice to dig 2 cutoff trenches perpendicular to the tunnel to a depth of 12” below the tunnel and 12” on either side of the tunnel to ensure that a good seal is created. Once all of the tunnels have been opened, mix the existing dam soil at 30% by volume with high-swell sodium bentonite clay.  Use a hand tamper, jumping jack compactor, or vibratory roller to compact the soil/bentonite mixture into the tunnels to prevent seepage through the dam. Finish the surface with 2 “ of topsoil and seed with a local grass seed for erosion control.

Muskrat damage to pond