Cecil, I guess I spoke too soon! I had trees in all sides of the pond but of course the first egg strand goes in on top of the leaves and about 5' away from any tree. It is exactly on the south pole of the pond in surprisingly shallow water (maybe 10"?) Probably where the water was warmest.
I rechecked temps and it is 50 or 50.1 degrees on both sides of the pond and over the site where the eggs were. None of the trees have strands and this is the only free floating one.