johnstaci,

Having recently completed the renovation/expansion of a pond that had several pine trees in and around the dam, I would say to you absolutely do not plant pine trees on or anywhere near the dam...not from a debris standpoint, but from the damage their roots will do to your dam. They have an extensive deep root system and even trees close but not on the dam will send roots into the dam to get water and disrupt the structure. Avoid them and if any get started, remove them....or there will be problems later on.