One additional thought regarding leaf introduction to your future pond- if much or most of the leaves don't drop directly from the trees into the pond location, i.e., they are wind blown after the leaves are on the ground- you may be able to reduce leaf introduction by planting shoreline plants to act as a sort of barrier/catch. You would still put extra nutrients into the water by trapping the leaves near the shoreline, but at least you wouldn't be putting nearly as much organic material directly into the pond to become muck. Just another thought that might allow you to keep some of the nearby trees. OTOH, if the trees are mature and tower directly over the proposed pond location, then you're sort of stuck with considering tree removal. As Mr. Cody said, allowing large leaf introduction into your pond will "age" the pond quickly and not lead to good water quality for your fish.