The high water table may cause allot of problems. If you build a dam, then the water will lower down to the level of the water table. It's not always a good idea to build on springs or wet areas.
Saying that, I built my pond in a wet area. At first, I didn't know how I was going to accomplish it, bu figured I'd work around the edges of it, and keep going in until it was too wet to go any further. I was hoping for 4 to 6 feet of depth, but wasn't sure how I'd get rid of the trees in the middle. As I cleared the land, and the ground became exposed, it started to dry out. The more I cleared, the better it got. Then as luck would have it, we started the first year of two years of a very bad drought. I got very lucky because it took my two years to build my pond.
During my digging, I also compacted the bottom of it. I also found the springs, which were on the side or shoreline of my pond. That's about where my full water level is at. Again, I got lucky in my plan so that it worked out this way.
If the springs had been lower, then I would have had to dig them out and pack them with clay. Water will go in either direction, depending on the amount of force on it. Put a million gallons of water above a spring, and it will become a drain.
As for your original question, there are a couple ways to do this. If you have it logged, have them take out the sumps at the same time. Around here, I'm told that the cost of the timber will offset the price to clear of stumps and make it ready for pasture. It's an even trade and you don't make any money on the logs, but you end up with a clear field. Having to remove the stumps after it's been logged is expensive and time consuming. It either takes a big machine or lots of hours. Either way, it's money out of your pocket and usually more then you can get for the logs.
A decent pond builder shouldn't have any problem with digging a pond within the boundaries you specify without disturbing your trees. If the water table is too high, he can dig a trench to drain or lower it.
An excavator and a bulldozer could probably do this in a week pretty easily once the trees are out of the way and your soil is workable. If the excavator has to take out the stumps, it will take a little longer. If they are burning, that will add time, but you can use the stumps and/or remains of the burn for structure for your fish. I was burning the entire time that I was building mine, and what was left got stacked into piles for the fish.
Eddie