Best time to travel to California

Monticello Dam Morning Glory Spillway in California 2024-2025

An enormous drain hole which looks a portal into another world is especially impressive during the rainy season

Best time: November–March

Monticello Dam Morning Glory Spillway
Monticello Dam Morning Glory Spillway
Monticello Dam Morning Glory Spillway

The Morning Glory Spillway also called as the Glory Hole by locals is the largest drain in the world. It is located on the Monticello Dam in Napa Valley, California.

The Monticello Dam can hold up to 2 billions kilolitres of water, but it should be drained. The main role of this spillway is to keep the dam safe and protect it from floods. When the level in the dam rises, the water runs through this huge hole down the concrete pipe at a rate of over 1,381,862 litres per second. The diameter of the hole is almost 22 metres at its widest part, slowly narrowing to the exit to 8,5 metres.

The hole can be seen from the adjacent road, but it is cordoned for safety reasons. The dam is definitely not the place for swimming, but for watching only. During droughts, the spillway attracts skateboarders and bikers.

Practical info

When is the best time of the year to visit the Morning Glory Spillway?

The optimal time to explore the Morning Glory Spillway, situated in California, is during the rainy season, i.e., from November to March. This period results in the maximum amount of water accumulation in the dam, creating a spectacular view as the water plummets down the spillway like the new entrance to another world. Show more

Where is the Monticello Dam located?

Located in Napa Valley, California, the Monticello Dam is almost 80 miles northeast of San Francisco, approximately 30 miles west of Sacramento, and around 12 miles south of Lake Berryessa. Show more

What is the capacity of the Monticello Dam?

Constructed by the U.S. Army Corps of Engineers in 1953, the Monticello Dam can contain nearly two billion kiloliters of water. The prime objective of constructing the Monticello Dam and building the Morning Glory Spillway was to preserve water and prevent any potential floods around the area. Show more

Is the Morning Glory Spillway accessible for visitors?

While visitors can see the Morning Glory Spillway from the adjacent road, it is not accessible to visitors for safety reasons. The area adjacent to the spillway is restricted. The Monticello Dam is a popular tourist attraction, easily accessible by both public and private transportation options. Show more

Why do skateboarders and bikers visit the spillway during droughts?

The dry season creates an almost empty Monticello Dam and Morning Glory Spillway, which attracts skateboarders and bikers. To explore the spillway safely, proper permissions from authorized personnel along with safety protocols must be followed. Skateboarders and bikers enter the spillway area and transform it into a skatepark, guiding their skateboards and bikes along the walls surrounding the colossal drain hole. Show more

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