Ok, not a stealth pond, but...
So the story goes that
Sepp Holzer was visiting a group of indigenous rebels, guerilla fighters, if you will. They needed a water source, but were not allowed to tap into the local water source, which, I believe, was on a military base.
So they built a stealth stream to get water without lettng anyone know. They eventually dig out a small stream, section by section. As they dug out a section, removing the top chunks of turf/grass and saving it, they then filled it in with rocks and then placed the piece of turf/top ground cover back on top of the rocks, so it would grow back into place, leaving an
underground stream of sorts. The built it section by section until they finally reached and tapped into the reservoir/pond on the military base. No one detected their work, and their water problem was solved.
Creative solutions are the best solutions,
Seth