Originally published 2018-06-16.
Have you ever driven along the highway and done a double take at something you saw in your eye's corner? This is a typical experience for people who pass by Lake Berryessa, the seventh biggest human-made lake in California.
That's because it has what looks to be a giant hole. Out of use for many years due to the prolonged drought in California, it has finally sprung into action again in early 2017, capturing the interest of a man with a drone.
If you're curious to know what the inside of the hole looks like, then check out the breathtaking video below:
Lake Berryessa, built against a 304-foot dam, is famous for its "Glory Hole" spillway, a fantastic sight to see when it is at full capacity, especially, as the video above shows, when it's captured from the perspective of a drone.
When the drone captured the footage, it was the first time the glory hole had been used in more than a decade. Because of the rain that fell in January and February 2017, the lake filled up in only a few days.
The hole's widest part measures a surprising 72 feet across, and it narrows to 28 feet across after a drop of about 200 feet. The water flowing into it passes through a funnel, which eventually drains out into Putah Creek.
YouTube user Evan K captured the impressive video.
The apparent hole is engineered infrastructure
The circular opening is a spillway associated with Monticello Dam, not a mysterious natural drain. Water entering the structure is carried away through a designed route. The camera angle makes that function look extraordinary because the familiar surface of a lake appears to end at a sharply defined edge.
The view does not reveal every dimension
The funnel is 72 feet across at the lip and narrows to 28 feet after a drop of about 200 feet. The spillway's measurements and operation should be taken from the responsible water authority, not estimated from drone footage. The recording can be appreciated as a view of engineering in action without implying that the area is safe to approach or that recreating the flight is appropriate under current rules and conditions.
Sources and context: Bureau of Reclamation: Monticello Dam
How the Glory Hole works
Monticello Dam and its spillway were built between 1953 and 1957. The Glory Hole starts to take water when the lake rises above 440 feet. The water drops about 200 feet, turns 90 degrees and runs through a pipe under the dam to an outlet about 700 feet away, spilling into Putah Creek, which flows on towards the Yolo Bypass. At full capacity the spillway drains 48,800 cubic feet of water per second. The spill of 20 February 2017 was the first in 11 years; the spillway has been used about two dozen times since the 1950s, and it began spilling again in February 2019. The opening is cordoned off with buoys and fencing.
Sources: ABC10: How the Glory Hole on Lake Berryessa works Atlas Obscura: Monticello Dam
COMMENTS