Heavy rains have inundated parts of California, flooding neighborhoods and roads and causing hundreds of evacuations.
The spillway can take in as much as 48,000 cubic feet of water per second when the lake reaches capacity. That's about the equivalent of draining half an Olympic-sized pool in one second, CBS News reported.
All the rain is also behind a rare spectacle in Napa County, that only occurs when the water levels reach a certain height on Lake Berryessa near the Monticello Dam. The lake has a spillway or drain, similar to a drain in a bathtub, which is breached when water levels rise more than 440 feet above sea level.
The lake's water spills over the funnel-shaped drain, called the Glory Hole, and flows 700 feet down to a creek below. From above, the drain looks like a bottomless pit that's sucking the water down and out of the lake in a whirlpool-like phenomenon.
The last time locals saw water rushing through the drain on Lake Berryessa was back in 2006, some 11 years ago.