It was likely man made when the development was built in the early 1990's. It is one in a series of many holding ponds for run off. If there is a downpour, the water actually comes up to the grass.
Thank you both! Your KBG is coming along nicely Togo. I am originally from MN and just recently relocated to AL. The look and feel of KBG will always be my favorite, although this Zoysia grass is not far behind.