I wonder if there is another source of water/spring that just so happens to be feeding the creek some of the water you are seeing? Hopefully not sourced by the pond... though what you are seeing may be the culmination of all of the water seepage under and around your area.
The real question is if your inflow can keep up with this outflow?
I think maybe another option would be to build a secondary pond downstream and capture/stop this water. If able, you could bring the level up to the existing dam or close enough to it that there isn't enough static pressure difference to force the leak any more. That would save needing to drain the pond, and you would have another BOW as a result of spending more $$$ rather than just shifting some dirt around. Just a thought.
