The world's largest drain called 'The Glory Hole' was only expected to be in action every 50 years, but extreme weather has ramped up its use to twice in 24 months

fusaromike / Getty‘The Glory Hole.’
  • The world’s largest drain is situated in Northern California.
  • It’s called the Morning Glory Spillway, or “The Glory Hole.”
  • It empties water from the Monticello Dam in Lake Berryessa to prevent flooding.
  • Although it was built to empty water once every 50 years, severe weather has meant it’s been used twice in the past two years, and four times in the last 22.

In the middle of the Monticello Dam in Lake Berryessa, Northern California, there’s a massive drain hole. It’s called the Morning Glory Spillway, but has also earned the affectionate nickname “The Glory Hole.”

At 22 meters in diameter, the hole sucks in water from the dam to prevent flooding at a rate of 1,300 cubic meters per second when it reaches capacity, according to Atlas Obscura. The water is carried through a large concrete pipe and emptied about 210 meters away.

The hole has been cordoned off for safety reasons since 1997 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.

Glory Hole Monticello DamAndrei Stanescu / GettyThe hole empties water from the dam at a rate of 1,300 cubic meters per second.

The Glory Hole was built between 1953 and 1957, and wasn’t constructed to overspill regularly. In fact, it wasn’t expected to be in use much more than once every 50 years.

However, the weather in Northern California has been unpredictable recently, and residents have experienced heavy rain for several weeks, with thousands of people evacuated because of floods. Due to this heavy rainfall and higher water levels, the Glory Hole has been used twice in the past two years, and previously in 2006 and 1996.

You can watch it in action below:

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