I think you need to make sure you know how big your pond is. Its hard to tell from the pics, but it just doesn't look like 10 acres to me.
1acre = 43560 sq ft
10 ac =435,600 sq ft
I would start by trying to get your hands on a handheld GPS and simply walk the perimeter to get the most accurate number. Short of that draw some lines using Google Earth and that should get you close.
As an Example, every person who has looked at my pond says its 1.5 acres...GPS says 1.15 every time. You can see how a 6 acre pond can quickly turn into "almost 10 acres" without actually measuring it.
