I have had something similar happen two years ago on my red clay dam after it was filled. I did not have any visible streams of water, just several wet spots and puddles that slowely filled. I have done nothing to fix them and most spots have gone away now. I am hoping the last few disappear this year.
It was so annoying the first year since I could not drive a tractor or 4-wheeler around my bond without sinking in the mud I ended up putting a drain tile around the edge of the dam. I then could also roughly measure the amount of seepage by what was coming out of the tile.
Good luck, I hope it works out OK for you!
