Yes - all earth bottom ponds leak to some extent. Some my be very "tightly compacted but there is still a tiny amount of seepage. It is the nature of soil, even compacted clay. Listen to Lusk and Otto's Facebook live next week Feb 10 Wednesday night and they will confirm it or should bring it up when dealing with this discussion. If you do not believe it, ask a soil scientist.
Another thing you can do to verify it is look closely at the soil bank above the water line. It is wet due to wicking of the water through the soil; water is actually leaking upward.
