An anti-seep collars are water tight fitted around the outside of the principal spillway. They prevent seepage by restricting the water flow around the outside of the principal spillway. Muskrats can also cause major damage to earthen structures. The borrowing habits of the animals can results in a destruction of earthen structures. Their borrows may cave in and cause leakage or lower the height of the structure.
Muskrats also destroy vegetation along the shoreline which helps prevent wave action erosion.
To control the problem muskrats can be removed by trapping or other methods during certain parts of the year. A lining of hardware cloth or chicken wire in an earthen structure will deter the animals from burrowing. They are generally used on smaller wetland projects to keep vegetated spillways dry. The concern being that the spillway is too wet to maintain vegetation. The opening of the intake should be at a lower elevation than the spillway.