wmaurer,

Welcome to the forum. Your posts in quotes below followed by my response.

"When the pond was dug...clay had to be pushed from the deep end to the shallow end and I don't think it was done very well. I am thinking that I am loosing water from the shallow end on the sides. The water level drops and holds...so I am thinking the bottom is ok and that I just need to add clay on the sides."

Generally in my experience ponds do not leak from the shallow ends unless there is some kind of underlying structure problem such as rocks or fissures or such. My ponds have no clay, only sandy soil in the very shallow ends and they do just fine. The water pressure is toward the deeper end, toward the clay dam. Water always flows downhill. That is where most leaks happen. Do you have rocks or some kind of bottom formation that caused them to push clay into the shallow ends?

"My shallow end...when full...could hold 7' of water. How thick should I put in the clay so it can hold the weight/pressure?"

If 7 feet is your shallow end, how deep is your deep end? Generally, if you have good clay, 2 feet thickness of clay is sufficient to prevent leaks through the bottom.

Something about this just does not compute. Someone dug your shallow end out to 7 feet which included pushing some amount of clay from the deeper end back into the shallow end? And its still 7 feet? It just does not compute to me.