Have done a search on this subject and am sure I have seen the answer somewhere but can't find it! The only water I currently have available (due to the dams drying up in our extreme summer) is a medium sized oval one with only 3 clearly defined edges (and they will probably turn into mud also if we don't get some rain). Am trying to figure out how to do this without giving the young dogs excessive swimming or running through mud. We started off on a smaller dam which was working really well but that has now dried up. Have never had the perfect one like Evan uses and posting a picture is beyond me! Any ideas greatly appreciated.