We have a 3/4 acre pond that is newly renovated. It was a cow pond that was full of everything bad. (trees, limbs, rocks etc.) that had accumulated over 50 years. The bottom of it is about 20 feet deep. It was full of watermeal and also full of water. It was cleaned out completely, all the muck removed to the red dirt we have in our area.

The pond now leaks. I don't see any obvious leaks in the dam. The dirt guy who did the work said there was enough clay that we didn't need to bring in any more. He also says that it will naturally seal over time and everything I read says that he isn't necessarily correct. I have read several posts where people have dug their pond multiple times. Like everyone else I would like to avoid draining it again.

I am not sure where to even begin....

If it is like the 1/4 acre pond on our place we renovated and re-dug almost three years ago, we made a mistake in not re-coring the entire dam. We only reworked the small part we enlarged.

It had lots of trees on top, behind, and on the water side of the dam, some up to about 15 inches.
It has been leaking ever since, and likely getting a little worse with time, as the root paths give a path for leakage. We have plans to start re-coring the dam in a week or two.

There is seepage (not obvious flowing) water all along below the dam that makes a swampy area about 100 feet long and about 50 feet wide as the pond loses 1/2 to one inch per day.

If your dam had trees and roots in the dam, that is likely your answer.

Hi Beefys

I've renovated a previously tight pond and ended up with seepage issues, it was frustrating and disheartening. Feel free to ping me anytime, I help many review solutions to pond leaks, some are free, some are not - depends on the nature of the suspected issue. My time is free to my Pond Boss family - holler if I can help.