So hard to get an idea of the lay of the land by pictures.
Is the old pond going to become part of the new pond? In other words, are you going to drain it?
I can tell you from experience, it takes more effort to clean out an old pond usually than just building a new one.
Is the lay of the land such you can build a new one and leave the old one as is or just clean up around the dam. Don't want do do short term fixes that lead to something that you do not want to end up long term. Just trying to give you some thoughts, not suggestions, because I can not get a good idea of the lay of the land.
