4000-5000 acre??? That might get you a hole-but not a "pond".
I feel I can safely say digging the hole is the easy part. What you do with the basin after that is what matters, but you need to be looking ahead at several things that I can tell you by experience, doesn't come to mind until the problem presents itself.
I would HIGHLY recommend you give a gander at the resource guide, find Otto's dirt work/construction, give him a call and talk it over.
If you've never built or managed a pond, get someone involved-hands on-that has. I strongly feel you will regret it if you don't.