Nestled in the rolling hills of Napa County, California, Lake Berryessa is a stunning reservoir known for its scenic beauty, recreational opportunities, and a peculiar marvel that captures the imagination of visitors from around the world: the Morning Glory Spillway, affectionately dubbed the Glory Hole. This funnel-shaped spillway isn’t just a functional piece of engineering—it’s a breathtaking spectacle that transforms into a swirling vortex when water levels rise, making it one of the most unique natural and man-made attractions in the United States. 🌊✨
A Marvel of Engineering
The Glory Hole is part of the Monticello Dam, which was constructed in the 1950s to manage water flow, provide irrigation, and control flooding in the region. The spillway itself is a massive, bell-mouth structure made of concrete, measuring 72 feet in diameter at its rim and narrowing as it plunges approximately 200 feet into Putah Creek below. Designed to handle overflow when the reservoir reaches capacity, it can drain an astonishing 48,400 cubic feet of water per second—equivalent to emptying an Olympic-sized swimming pool in mere seconds!
Unlike traditional spillways that direct water over a dam’s edge, the Morning Glory Spillway’s unique funnel design allows it to siphon excess water in a controlled manner, preventing damage to the dam and surrounding areas. Its resemblance to a giant drain, complete with a hypnotic vortex when active, has earned it the nickname “Glory Hole” and a cult-like following among engineering enthusiasts, photographers, and curious travelers.
The Vortex in Action
The Glory Hole is most captivating when Lake Berryessa’s water levels rise above the spillway’s rim, typically during California’s rainy season (late fall to early spring). As water pours into the funnel, it forms a swirling vortex that looks like something out of a science fiction movie. The spiraling motion is both mesmerizing and slightly unnerving, as the sheer power of the water is on full display. When active, the spillway creates a low, rumbling sound that adds to the otherworldly experience.
However, seeing the Glory Hole in action is a rare treat. California’s drought cycles in recent years have meant the spillway activates infrequently. It famously overflowed in 2017 and 2019 after heavy rainfall, drawing crowds of spectators who flocked to witness the vortex. During drier years, the spillway remains dormant, with water levels staying below its rim, leaving only the eerie, dry funnel visible—a stark reminder of the region’s fluctuating water conditions.
Why It’s Called the “Morning Glory”
The spillway’s official name, Morning Glory, comes from its resemblance to the funnel-shaped morning glory flower, which has a wide opening that narrows into a tube. The nickname “Glory Hole,” while catchy, has sparked some giggles due to its unintended connotations, but locals and visitors embrace it with a sense of humor. Regardless of what you call it, the spillway’s unique design makes it one of the largest and most iconic of its kind in the world.
Visiting the Glory Hole
If you’re planning a trip to Lake Berryessa to see the Glory Hole, here’s what you need to know:
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Location: The spillway is located near the Monticello Dam at Lake Berryessa, about 40 miles northeast of Napa Valley’s wine country and roughly 70 miles from San Francisco. The closest access point is along Highway 128, with parking areas and viewpoints nearby.
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Best Time to Visit: The spillway is most likely to be active between February and April after significant rainfall. Check local news or water level reports for Lake Berryessa before planning your trip, as the vortex only forms when the reservoir exceeds capacity.
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Viewing Tips: Bring binoculars or a zoom lens for photography to capture the vortex’s details. The best viewing spots are along the dam’s access road or nearby trails, but stay within designated areas for safety.
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Safety First: The area around the Glory Hole is strictly off-limits for swimming, boating, or kayaking. The currents near the spillway are incredibly dangerous, and warning signs are posted to deter adventurous visitors. In 1997, a tragic incident occurred when a swimmer was pulled into the spillway, underscoring the need to respect its power.
While you’re at Lake Berryessa, take time to explore the reservoir’s other attractions. The lake is a haven for boating, fishing, hiking, and picnicking, with over 165 miles of shoreline to discover. The surrounding hills bloom with wildflowers in spring, and the area’s proximity to Napa Valley makes it an easy addition to a wine-tasting itinerary.
A Natural and Cultural Icon
The Glory Hole at Berryessa is more than just a spillway—it’s a symbol of human ingenuity and nature’s raw power. Its striking appearance has inspired countless photos, videos, and even references in pop culture. Drone footage of the vortex has gone viral on platforms like X, showcasing its hypnotic swirl from angles that highlight its scale. For locals, it’s a point of pride; for visitors, it’s a bucket-list destination that delivers awe and wonder.
Whether you’re drawn by the engineering marvel, the thrill of the vortex, or simply the chance to witness something extraordinary, the Glory Hole at Lake Berryessa is a must-see. It’s a reminder of how even the most practical structures can become extraordinary when paired with the forces of nature.
Plan Your Adventure
Ready to witness the Glory Hole’s swirling spectacle? Keep an eye on Lake Berryessa’s water levels and plan your visit during the rainy season for the best chances of seeing it in action. Pack a camera, respect safety guidelines, and prepare to be amazed by one of California’s most unique attractions. Have you seen the Glory Hole in action, or is it on your travel radar? Share your thoughts in the comments below!
