I believe sprinkling bentonite is a waste of time and money. It might be Ok to attack a specific leak. Cecil Baird tried it and I recall that it worked for him but he didn't just sprinkle it in the dam area. I have never seen a contractor who would guarantee a fix using bentonite. I attended a pond seminar a couple of years ago and there was a speaker from a bentonite dealer. He said sprinkling is the least effective way of using it.

An inch of water a day or every couple of days probably isn't much when you factor in summertime evaporation. Most ponds are going to leak a little bit. Also, Some of the water might be rain that has fallen on the back side of the dam and is running down hill to exit at the bottom. You also have to figure that if it has recently filled, water is still soaking back into previously dry sides and dam. Trees and grasses around the sides and dam are going to get some. You probably won't have a mud hole. It can take several years to get the pond to stabilize.