A picture or two would help, but I would think that your dam would not be too different from any other. You will need to create a core of good clay, pack it tight, and get some grass or other vegetation on it. 100 acres is a lot of watershed so when you get a terd-floater, you are going to get so much water through the pond you will probably lose any fish in it. I would also be concerned that you may end up with nothing but a silt trap. Again, some pictures would help.

Hey Moe, I'm trying to think but nuthin's happening!