Lake Berryessa is currently the seventh largest man-made lake in California. Water from the reservoir primarily supplies agriculture in the Sacramento Valley downstream. The dam is noted for its classic, uncontrolled morning-glory-type spillway. Locally, the spillway is also known as the "Glory Hole". In addition, parts of the lake's watershed extend into Lake County. About , acre feet 0.
Lake Berryessa’s ‘Glory Hole’ Spillway Active For First Time Since 2017
How the 'Glory Hole' on Lake Berryessa works | abccom
At 22 meters in diameter, the hole sucks in water from the dam to prevent flooding at a rate of 1, cubic meters per second when it reaches capacity, according to Atlas Obscura. The water is carried through a large concrete pipe and emptied about meters away. The hole has been cordoned off for safety reasons since when a woman was pulled in and drowned. During the dry season, when the exit of the spillway is visible, skateboarders have been known to use it as a ramp — although this isn't recommended. Otherwise, boats and swimmers cannot get too close.
There is a mysterious hole in Lake Berryessa in California. It is just a really big drain called a spillway. And once you see it full of spiraling water, it is hard to take your eyes off it. For the first time in a decade, January and February have brought so much rain that the lake in the Napa Valley area north of San Francisco has maxed out its water capacity.
Crowds watch mesmerized by the sight of water spiraling down in the middle of a lake. When water levels rise above feet, water starts spilling down the hole and into Putah Creek, hundreds of feet below. As of March 22, the water level was a full foot above the spillway. You can check the level here.