Your dredging idea Will work just takes lot's of hours. I use a 3" trash pump set on the bank and reduce the pipe to 2" I run pvc pipe out in the pond and then put flexible intake pipe on it. I pump up to an above ground pool then I let it settle and drain the water back to my bait fish pond. I have a 4" pipe out the bottom to a pit for the muck. Works pretty well and I save my water.