ETW,
I like ponds...especially ponds that hold water. So, I would cover that gravel in two feet of good packed clay and wait for the fall rains to come.
Maybe you could sell it and make some money, maybe not. Maybe you could use it for something else...but if you want a good pond, cover it up with good packed clay and enjoy the pond and forget the gravel....that's what I would do, cause I like ponds more than gravel.
