I have a small fish pond in my horse pasture, less ...

I have a small fish pond in my horse pasture, less than an acre I would say. I spent $10,000 having this pond put in and it leaks. The dam is 200 feet long and about 15 feet high. It is constructed of packed clay and topsoil. The pond does not leak at the dam - the water runs underground and surfaces about twenty feet from the dam. Once you dig down about 5 or 6 feet you hit solid rock. That sandy clay mix kind of rock. It is very pourous and I'm sure widespread seepage is the problem. I have been told to put cows, pigs, chicken poop and other crazy things in to stop the leaks. I would greatly appreciate any help or solutions youhave to offer. Thanks!!