elbafishing,

My condolences to you also.

It is very likely that you can simply rebuild the top structure on the existing posts. Can you see any damage to the posts? Seems unlikely that they would be damaged at and below the water line. Just rebuild the above the water line stucture on the posts.

Beaver, there are some experts at trapping them here on the forum and hopefully they will jump in....but one thing for sure, you can't let them stay and expect to have a viable pond dam. I hope you do decide to keep up your Fathers pond.