You definitely want the water pumped out, trust me. I have been digging a 20 acre pond in a sand pit at work with a 345 Cat excavator (big) the last few weeks and the pond is full. They are using the water from the pond to wash the sand so it must stay full. It sucks not being able to see what you are digging, and you can't properly dig shelves and contours into the bottom and sides. Also an excavator will NEVER get the pond more than 8-10 feet deep without pumping the water out and driving the excavator down into the hole to get deeper. Finally digging without pumping makes a BIG mess. Sand and clay full of water cant really be piled very high, and the water runs everywhere.
Here are some pics of my pond when it was done by a friend who is not in the pond digging business (no one really is except Mike Otto) but he has dug about 20 ponds.
home and pond pics
