My parents have a 1 acre round pond that i think has a crack in the bottom. They live in trenton and the soil is very rocky and I think when The guy dug their pond he didnt put any clay in it. It held water about half way to full when it rained for five years. After this may with all the rain I guess the pressure cracked the bottom because the water went down rapidly and drained losing all my fish I caught and stocked. I was thinking if I brought in loads of clay and rolled the clay about a foot deep if anybody thought that would work or had any ideas. Pond is 20' deep. I think I will put some structure in it too since we are starting over.