I have been a surveying technician for 14 years. NOWADAYS, on the waters of, literally means that. As water's edges change, so does the land that the person owns. The boundary of that line is not definite, it meanders. Trees were used as landmarks to mark peoples properties, nowadays they do not use them, but set iron pins in the ground or in concrete. Creeks can dry up, change courses, so in 200 years, they may no longer exist anymore. I hope this helps.