Hey NC - great looking place and congrats on the find - it looks very nice. Here is my honest feedback from reviewing the photos:
Depth of pond is troubling. Looks pretty shallow with very gradual slopes - that can lead to many issues including excessive vegetation, winter or summer kill, and obviously droughts affect shallow BOWs much more than deeper ones - so that worries me, too.
I am concerned about the trees on the dam. Otto says any trees under 4" can be safely removed, anything over you have to leave them and hope for the best. Appears as though the backside of the dam has trees growing - I worry these could become an issue down the line. If a tree dies, it's roots rot, and this leaves a fissure in the dam which allows water a path to follow. Over time that can create larger leaks which could eventually lead to dam failure. We've seen that on the forum too many times...heartbreaking!
Buying a spread with an existing pond saves a lot of time and $ in planning/engineering your own - but this pond looks as though it's been around for a long time due to the apparent lack of depth, and has some potential dam issues with the trees growing there. It would be a bad scenario buying a pond then having to start all over with excavation and new dam construction.
If it were me I would accept the fact I'm going to have to rework the pond through excavation and dam work or find a different place and start from scratch building a pond of my own design. I'm not an engineer - just my two cents trying to look out for you. Really beautiful setting out there - I hope you can make it work!