Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Drain and Bulldoze, or Excavate?

Not a pro here, but I would dig a temporary catch-basin, hay bails, small dam, etc. behind the dam to catch the silt coming out, cut the dam as a narrow channel to begin with, and take advantage of the stream (depending on the flow) to erode a lot of the material out for you. Maybe help it along with a trash pump to stir it up along the edges to wash it out. Then you can get an idea of actual depth to know how much material you actually need to be rid of.

Once you have a grip on it, let it drain, widen the hole to the size of the dozer when/if it comes time.

The concern is if it was really 25ft deep once, there will be a hell of a lot of pudding to deal with. I doubt if it is that deep that the goop will dry out before we kick the bucket, but the goal is to get enough water out of the silt/muck that it can be dealt with.

As people are alluding to, it is complex and messy work to drain with a steep price. Building up the dam is likely cheaper and results in a usable pond until it too fills with silt.

If you go the draining route, once cleaned, it may make sense to install a bottom-feeding siphon system that will at least excavate the areas where the pipe sits.