Did you renovate/enlarge an existing pond, or have you already had two contractors work on a new pond build? If there was a pre-existing pond, did it hold water?
Unless the high spot was for fish structure, then they may have left it because they were encountering some sand in the bottom at that location?
Pushing out the high spot may have caused the leak since they probably packed clay in the deep spot when they filled it. However, if the slopes of the high spot were not blanketed and packed, then that could be the source of the "bottom" leak if the water entry point is low enough.
I have read several threads on Pond Boss where large amounts of water were leaking from a pond, but some damp ground was the only evidence (other than the water loss).
It is amazing how much water trees and grass can take up from the ground. We have a creek on our property that is tied to the level of the groundwater. It would actually rise in the fall. For the first few years, I would go out to work and note the higher water level, and assume I had missed seeing some rains. It turns out, that the groundwater level would rise substantially after the first hard frost made the trees and prairie grass go dormant.
It sound like your pond project may be on hold for a while due to budget constraints. If possible, I would recommend re-filling the pond again in November? Maybe you can walk your ditch after letting the pond leak for several days and see if you can spot the water to gather a little more info.
