"What do you do if you can't pump the water fast enough"
As stated by others, it makes it pretty darn rough. Perhaps Mike Otto could relay some times he has handled that type of situation. I will add here, that Mike has a new book out about digging ponds. You might want to get a copy of that ASAP. I have not seen it, but others here have given it good reviews, and Mike is probably to modest to suggest that you buy it.
Having been thru the experience, I still think that the best piece of equipment for that type of scenario is a dragline with a sauremans bucket. But you can't just go out and start buying equipment, can you. Got to make do with what you got. I am a little worried for you on the size of machine you have, and the amount of dirt you need to move.
You don't need a true trash pump like you mention above, but you will need to keep the intake up out of the mud so it don't suck up any stones, like Blair said. You can push the water a long ways. You can't pull the water much. I'd get the pump as close to the water as possible. That's in height too. Then push the water. Besides, the suction hose will cost the money, the discharge hose is cheap. I also want to throw out there, tread carefully as to where you pump the water. Into a river? You just may not be able to use a pump for that reason and your back to step one. Nobody else has brought this up, because they all want to pump(and it is the best way), but you do have to consider the fact of where you are pumping to and it's effects.
