Cecil,
If you have a lot of crawfish, the outlook is not good. If your dyke's are wide, chances are slim they will cause a leak. If narrow, chances are much worse. I wouldn't want to put anything in the holes that I wouldn't want in my pond, because all that stuff will eventually make it into the pond and nearby wells.
They hate salt or sand in their holes, and will vacate and make a new hole nearby. It may be less work in the long run to widen your dyke's.
