Sounds similar to my pond in both size and heavily treed surroundings.
I elected to redo the existing pond which was 1.5 acres only 3' deep.. I started by removing trees and brush on all sides that were within 30' of the pond edge. This was necessary and well worth it.
I had my pond drained by digging a ditch to a nearby creek. It was empty in about 2-3 days. It was drained in February and sat until late August before it was hard on the surface. I was able to walk across and even ride my atv on it..but when the heavy excavator w/ 70' boom drove out it sunk like a rock! I have pictures of it stuck. The contractor was able to put down floating pads that he could park the excavator on and work from.
There was 3' of muck before hitting clay from the years of leaves etc. They worked on it for about a week straight. Lots of muck, lots of dirt that had to be removed. Very labor intensive. Once they hit clay the dozer could get in there and work it and shape it..
End product was 2 acres w/ average of 5-6' depth, an 8' hole on the West end, and a 12' hole on the East end.
Due to the lay of my land, I believe this was the best place to have a pond so for me redoing the existing pond was worth it. I was sure to install a drain that would let me draw down the water and work on the pond if needed in the future.
