Backyard Pond Liner

• While moles are not typically known for causing damage to ponds or chewing through vinyl liners, this is not to say they are not capable of it. Moles have elongated front teeth that they use to chew through roots and tough soil. Theoretically, they could also chew through your pond liner. If the moles are already presenting a problem in the rest of your garden, you may want to place deterrent in their holes to encourage them to move on. A natural deterrent is castor oil, which does not harm the moles but will convince them to seek greener pastures if poured around your pond where you have seen them burrowing.
  
  

Soil Erosion

• In the process of creating their tunnels and burrows, moles may make voids, or holes, in areas surrounding your pond. They may remove the soil around a portion of the liner, causing tears, cracks, and splits in in liner due to lack of support. If moles appear to be burrowing in the area directly surrounding your pond, use deterrent or commercial traps to remove the problem animals. In addition to using castor oil, place a pile of cow manure in an unused portion of your yard to harbor the earthworms your moles are digging to find and lure them away from your pond.
  
  

Marginal Plant Damage

• If you have marginal plants situated between your pond and the rest of your garden, watch for root damage caused by the moles. Moles prefer moist and damp soil, and thus will be naturally attracted to the area immediately surrounding a pond. Moles can chew on and disrupt the root systems of plants, and may be damaging your marginals.
  
  

Possible Contamination

• Moles are not a big threat to ponds, either natural or artificial. They do present a pest problem for agricultural areas, as they cause damage to crops and can also contaminate livestock feed. Their burrowing through fermenting silage, or livestock feed, will contaminate the feed with dirt and debris that is not digestible for livestock.