The entire sand beach is well above the current water level with no fabric extending into the water. With that said, the clay berm would need to be pretty close to the current water's edge or it may be too shallow if I add the berm to raise the bottom of the beach by 12". Doing that as close as I can to the water now may only leave the depth there at about 5 or 6'.
You mentioned that "It just needs to be far enough onshore so that there is no wave erosion on the back side of your berm." I don't think I entirely understand this statement. As the water continues to rise, it will eventually be in contact with the berm. With 5 acres of water, there will almost certainly be some waves. So I'm guessing that may be an issue and the reason why some have chosen to use concrete blocks?
