RobA,
I faced a similar problem this year on a smaller scale...rennovating 1/4 acre into 2 acre pond...DIY. After looking at it and getting some advise here, I decided that it was far better to just raise the dam height than to dredge or remove the sludge with a track-hoe. So, I lowered the water level down to only a foot or so remaining and then, with my dozer pushed the sludge/muck into an island in the middle of the pond..an island that will be covered by about two feet of water with the surrounding water depth of 8 feet(by raising the dam height). Something to consider...and very cheap and very good bass structure.
