At the far end of Hong Kong's Lantau Island from the new Disneyland is the tiny hamlet of Shek Pik, right on the sunny seaside. Zoom back, though, and you'll see the Shek Pik Reservoir peeking at the village over the brim of an earth-covered berm.
Perhaps the residents are simply unaware of the potential peril. Maybe they were told the "dam" was a wall to keep out the mainland communists, and whatever you do, don't go up there.