The iconic concrete whirlpool at Lake Berryessa, colloquially called the “glory hole”, has sprung back to life. After six years of dormancy, this striking feature is once again fully operational, funneling thousands of gallons of water per second into its massive circular opening. Situated in Napa County’s rolling landscape, this captivating display has reappeared thanks to an especially wet winter season.
Winter Rains Bring the Vortex Back to Life
A captivating natural engineering marvel has returned to Napa County: the celebrated “glory hole” spillway at Lake Berryessa is flowing again for the first time since 2019. Heavy storms elevated the lake’s water level beyond its critical threshold, causing water to cascade down the enormous circular drain starting in early February, drawing interest from engineers, tourists, and social media enthusiasts worldwide.
This year’s precipitation boosted Lake Berryessa’s surface past the activation point near the Monticello Dam spillway. As of March 13, the water level was roughly six inches above the rim. While it is anticipated to fall below the spillway soon, additional rain could extend the vortex’s activity into the coming week.
The structure, known officially as the Morning Glory spillway, functions as an emergency outlet for excess reservoir water. When lake height exceeds 440 feet, water rushes into the 72-foot-wide funnel and drains into Putah Creek, protecting the dam from flooding. Typically dormant and dry, on wetter years this impressive feature transforms into a powerful whirlpool that appears to drain the lake itself.
A unique phenomenon, dubbed the ‘Glory Hole’ spillway, was activated at Lake Berryessa in California after a storm swept through the area. pic.twitter.com/6jzVmOd3PT
— USA TODAY (@USATODAY) February 14, 2025
A Remarkable Blend of Nature and Engineering
Constructed in 1957, the Monticello Dam was created to impound Putah Creek and form Lake Berryessa. Because the surrounding Devil’s Gate canyon was too narrow for a conventional spillway, engineers designed the distinctive circular drain—a rare but visually stunning solution that still captivates decades later.
“It’s truly mesmerizing,” said Peter Kilkus, who closely follows the spillway’s activity through his Lake Berryessa News platform. Visitors often stop along Highway 128 to admire the vortex in action.
This unique structure stands out not only for its practical role but also for its surreal appearance. While comparable circular spillways exist at Whiskeytown Lake and Trinity Lake, none compare to Lake Berryessa’s in terms of popularity and photographic appeal.
Crucial Water Supply and Fleeting Natural Wonder
The San Francisco Chronicle reports that Lake Berryessa supports over half a million residents in Solano County by providing urban water supplies and farm irrigation. While most discharged water is used for agriculture, the reservoir also sustains local industrial and domestic uses.
Chris Lee, general manager of the Solano County Water Agency, explained that the reservoir’s water levels depend on more than just total rainfall, noting, “The amount of water in the reservoir is determined by a number of factors, including not just the amount of winter rainfall but also its duration.”
Viewing Tips and Future Outlook
To ensure safety, buoys are placed near the spillway to prevent access by boats and swimmers, but land-based visitors can watch the vortex from a nearby highway viewpoint. Spectators are advised to exercise caution, as the swirling water and steep drop-off are as hazardous as they are visually impressive.
The last time the glory hole operated was in 2019, with a previous activation in 2006. Its presence is entirely dependent on variable weather patterns, runoff, and reservoir operations, making it an unpredictable event.
In a region often challenged by drought and depleted reservoirs, the resurgence of Lake Berryessa’s dramatic spillway is a powerful reminder of the forces of nature—and their unexpected displays.
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