If you have the pond-itch and a budget to back it...I would definitely consider having it dug back out to its original depth. It's hard to say from the pictures, but it looks like and older pond that has mucked in over the years and is now rather shallow. Depth is a good thing for a pond's longevity and having it renovated would also allow for the old pipe to be dug back and properly removed or capped/sealed. A shallow pond also grows pond weeds more easily. Having it dug out will also take care of the current trees and unwanted vegetation.

Welcome to PB! Getting the pond back will be a nice backyard feature.

Fish on!,
Noel