I live in Atlanta GA, but I have a large pond in middle GA (Sandersville). I notice this water coloration as well. In the Atlanta area the water from creeks, streams, and springs, are always either clear or have a greenish tint when they go into a pond or lake. But when I go to the middle or southern part of the state I always notice that the water has a dark tint to it...like tea, and this is for most all water sources in this part of the state, even my pond. I also observed that this difference in coloration occurs just below what is called the "Fall Line", which runs all the way up and down the south east coast (Georgia, South Carolina, North Carolina). Is there an advantage or disadvantage to either type of water? If there is what is it? This could be influential to the sites I chose to look for my next pond or lake..