Theo,
When I had my pond built we got a small rain and had to build a small berm to contain the runoff to finish the upper pond end. Anyhoo, I had the builder lay rootballs on top of the berm which is now referred to as the Budweiser Crown and all types of fish gather around the area. You'll be real happy with a reef feature!
This is the crown and the tallest stump will be 2-3' underwater at full pool. BTW if ANY rock is in the rootwad they will never float!
