Mark, nobody can really tell you where the leak, if one exists, is coming from. New ponds have a lot of dirt to saturate. It is common to fill a new hole with water and have the water level drop. However, if you hit a sandy area, most likely it won't hold water. Sand is the usual strata of an aquifer and generally the source of leaks. The Bentonite sellers recommend that you till it into the soil. However, I have never seen one that would guarantee that it works. Do a search on this site for bentonite. You can also do a full www search and learn a lot plus talk to some pro's. Good luck.
