Following Years-Long Drought The World’s Largest Water Drain in California is Reawake

By: Alyssa Miller | Published: Jun 08, 2024

After heavy rainfall over the winter, California’s largest reservoir in Napa County has seen its water levels rise once again.

Now at its highest in years, the reservoir’s refilling is great news for nearby residents whom water shortages have burdened over the past few years.

Water Spills for the First Time in 4 Years

Over the last four years, the Morning Glory Spillway at Lake Berryessa has been activated. The 72-foot diameter concrete funnel directs excess water to Putah Creek.


Source: Shellie/Flickr

The Morning Glory Spillway is a 72-foot-wide inverted bell that channels water from the Monticello Dam into the creek below.

How the Spillway Works

According to the Watershed Information & Conservation Council of Napa Valley (via The Cool Down), the water drops 200 feet straight down toward a narrowing pipe.

Monticello Dam and the Morning Glory Spillway

Source: John C Bullas/Flickr

“It’s all curved, so you have the least resistance for the water to go down The Glory Hole,” Jim Daniels, district engineer for Solano Irrigation District, told the WICC. “And it’s very efficient. It’s not very turbulent… actually rather placid. It’s not that placid down inside The Glory Hole itself.”

The Winter Storms Affects on California

The February 2024 winter storms brought an atmospheric river to California, causing significant trouble for residents.

The floods in Dubai. The flood is covering a large part of the road. Some cars are in the flood and have been abandoned, with a person walking along the roadside. Other cars are parked up on the dry bit of the road, trying to escape the flood.

Source: @d_feldman/X

Twenty million people were under flash flood alerts as roads and airports shut down due to power outages and mudslides.

The Perks of the Winter Storms

According to Newsweek, the world’s largest drain hole has not been operational for four years, as water levels at Monticello Dam have been troublingly low.

A group of people in the water by a river in England, with green trees and fields in the distance.

Source: Rijk van de Kaa/Unsplash

However, the intense storms, exacerbated by the El Niño weather cycle, have brought more water to California reservoirs, though not without consequences.

The Consequences of the Winter Rains

Rising global temperatures make weather conditions increasingly unpredictable, making it harder for Californians to figure out how much water needs to be preserved as summer approaches.

Rambo Pacifica road was closed due to a landslide caused from severe winter storms. Public Assistance is authorized to State and local governments for emergency work and the repair and replacement of disaster damaged roads, bridges and facilities. Adam DuBrowa/FEMA

Source: The U.S. National Archives/Flickr

After years of drought conditions, California welcomes the rain, but the intensity of the storms has brought a new threat.


Locals Don’t Mind the Extreme Weather 

However, many residents are enjoying the benefits of the extreme weather conditions as it has alleviated times of severe drought.

Morning Glory Spillway in the Monticello Dam in California

Source: Wikimedia Commons

For the time being, locals can enjoy the breathtaking sight of water spilling into the Morning Glory Spillway.


Locals Celebrate the Rains

The overflow came after the Napa Valley Register reported concerns that there wouldn’t be enough rain during the wet season to bring the lake up to spillover. The excitement over this glorious sight has left residents ecstatic.

A closeup of raindrops on the ground

Source: Pixabay

“Everyone wants it,” Peter Kilkus of Lake Berryessa News told the Napa Valley Register (via Newsweek). “That lake is essentially full. … We’re all very happy that it’s full.”


The Excitement Around the Spillway

This isn’t the first time that residents have waited a few years to see water spill over the Morning Glory Spillway.

The dam almost being filled but not spilling over the Morning Glory Spillway

Source: daveynin/Flickr

In 2017, residents were so desperate to watch the spill that they manually sent water splashing down the spillway for the first time in 11 years by using powerboats after the lake was inches short of naturally spilling over.


Other Reservoirs Benefit from the Winter Rains

Lake Berryessa is not the only reservoir experiencing significant changes after the winter rains. The Great Salt Lake in Utah, which has been showing signs of lower water levels increasing, is receiving water from a full Utah Lake.

A view of the Calaveras Reservoir in California seen in the daytime.

Source: Ludwig Theodor von Ruhm/Unsplash

The wetter-than-usual winters have allowed the snowpack to melt, trickling down the mountain and into the lake.


The Benefit of Reservoir Refilling

This is great news for many residents and states that have been watching the lake slowly dry up, risking the ecosystem that surrounds it.

Person Swimming on Body of Water

Source: mali maeder/Pexels

The influx of water has helped refill the lake and support the aquatic creatures and migratory birds. Residents can also breathe a deep sigh of relief as the threat of toxic dust on the lake bed has not yet been exposed.


Do Your Part to Help

However, water levels will reduce again as summer approaches. To help maintain the water levels of these reservoirs, take action by shutting off the tap when you are not using water.

Close-Up Photo of Water Drop

Source: Nithin PA/Pexels

According to the Environmental Protection Agency, turning off the tap while brushing your teeth can help save eight gallons of water.