Andrew Sim

The primary purpose is to provide an inner wall that would allow me fill in more soil/gravel around the ponds edges to make them shallower. It gets deep fairly quickly at the edges of the pond and I think I'd have much better luck with plant/animal life if I could create a wider band around the pond's edge that is shallow. Some secondary reasons would be containing plant growth in the swimming area more easily and the ability to swim laps,.  

Does anyone have experience converting a pond into a natural swimming pool? I've got a small spring-fed pond (about 85 feet by 35 feet) that is lined with natural clay soil in the Northeastern US. It has a pretty consistent water level (though it goes down a bit at the end of a hot summer) and clean water based on testing. I'd planned to turn it into a natural pool by building a rectangular frame into the center of it for a swimming area, putting a layer of pea gravel down over the clay, and building up the soil and life/plants around the edges. Does anyone have experience making a natural pool like this from a pond instead of digging it and using a liner?