In this aerial photograph the Morning Glory spillway at Lake Berryesa is seen dropping water down a vertical spillway into Putah Creek in Napa, California, on March 14, 2025. This spillway has become affectionately known by Northern Californians as the "Glory Hole." The circular drain is 72 feet in diameter and sends overflow water 200ft straight down through a large tunnel and eventually downstream to control water levels at the Monticello Dam. (Photo by JOSH EDELSON / AFP) (Photo by JOSH EDELSON/AFP via Getty Images)
Napa, California – An awe-inspiring and unusual sight has returned to Lake Berryessa for the first time since 2019: the activation of the famed Morning Glory spillway, more commonly known by locals as the “Glory Hole.”
The massive, swirling vortex, measuring 72 feet in diameter, formed as water levels in the lake exceeded 440 feet above sea level, triggering the unique drainage system built into the Monticello Dam. According to Jennifer Onufer of the Bureau of Reclamation, which oversees water resources in the region, the phenomenon may remain visible for about three more weeks, depending on the weather.
While the sight of a vast circular hole in the water may strike some as eerie, it is a crucial safety mechanism. The spillway prevents the dam from overflowing by directing excess water through an enormous funnel-like drain, which then releases it into Putah Creek. Unlike traditional spillways that rely on chutes or shafts, the Monticello Dam employs this rare design due to space constraints, creating the dramatic visual effect.
Local historian and scientist Peter Kilkus explained that the Glory Hole spillway is an extremely rare engineering marvel.
“There are only two in California, and a couple others in Europe,” Kilkus explained, noting that reactions to the sight vary widely. “Some people say, ‘Oh, that’s really beautiful.’ Some people say, ‘That’s frightening.’”
The spillway, which typically remains dormant, emerges only when Lake Berryessa reaches a critical water level. The most recent activation was first recorded on February 4, with peak water levels reaching 443 feet on February 14, according to KTVU 2. The heavy rainfall and wet winter conditions across Northern California contributed to the lake’s rising waters.
The agency is urging boaters to exercise caution around the spillway and adhere to the region’s newly implemented invasive mussel prevention protocols.
Despite its striking appearance, the Glory Hole spillway has been the site of past tragedies. In 1997, a woman was tragically swept into the vortex after ignoring safety barriers and venturing too close. Authorities continue to emphasize the importance of respecting safety guidelines while viewing the spectacle.
For now, Northern California residents and visitors have a rare opportunity to witness one of the most unique hydraulic engineering feats in the world—one that blends the forces of nature with human ingenuity in a breathtaking display.
