Here Is The Stunning Truth Behind The Mysterious Hole Inside Lake Berryessa!
Reason

The reason why spillway continued to evade the eyes of people is because of a drought that had clouded California for over a decade. You see, the water level of the lake was all-time low during those years and hence the spillway was left closed. Usually, the spillways are created on the sections of the dam wall or above them. This one was designed differently, giving it a whole new look.