Trees and brush may not be a problem around the pond—but any trees or brush on the dam should be removed. That’s because the large root systems can provide seepage areas for water to escape. When trees fall, they can rip a large chunk of the dam out with them, which can lead to further problems down the road.
Your best bet is to keep the dam and any other vulnerable areas of the bank clear of trees and brush. Small stumps and sprouts can be removed entirely if no excavation is required. For larger stumps that would require major excavation to remove, grind them down to six inches below the soil surface, then fill the remaining hole with compacted clay soil.