A large man-made hole is located in Northern California, USA. But it is not just a hole. Drain hole in the tank of Monticello Dam – the largest spillway in the world

A large man-made hole is located in Northern California, USA. But it is not just a hole. Drain hole in the tank of Monticello Dam - the largest spillway in the world

A large man-made hole is located in Northern California, USA. But it is not just a hole. Drain hole in the tank of Monticello Dam – the largest spillway in the world