What Would Happen If Hoover Dam Collapsed?

As we saw in July with the earthquakes in Southern Cali, and your earthquake answer at that time, Las Vegas is susceptible to earthquakes and could sustain major damage. But what about Hoover Dam? Are there any dangers it could collapse? And if it does, what would happen?

Hoover Dam was completed in 1935, almost 85 years ago. Compared to most other structures in southern Nevada, it's old.

But compared to, for example, the pyramids in Egypt, it was built last Saturday. Also, it was built to last "indefinitely" and is about as solid as it gets: seven million tons of concrete and 660 feet thick (as wide as a 60-odd-story building is tall) at the bottom.

No one can know for sure the result of a disaster of the magnitude of Hoover Dam collapsing, for whatever reason. But if the roughly three and a half trillion gallons of water currently in Lake Mead were suddenly unleashed, they'd cover around 10 million acres to a depth of one foot. (Maryland occupies nearly eight million acres.)

Certainly, the water would overflow the banks of the original Colorado River and inundate downriver communities such as Laughlin and Needles, Lake Havasu, Parker, Yuma, and San Luis Rio Colorado before emptying into the Gulf of California on the east side of the Baja Peninsula.

How far the water would spread from the riverbanks is unclear, but it would probably wipe out a good section of southeastern California, all the way to the Salton Sea, an area that the Colorado regularly flooded before Hoover Dam was completed (and was a large part of the reason the dam was built).

What would happen to Las Vegas is a matter of even greater conjecture. It wouldn't be flooded, since the water would start draining southeast of the city and rush south down the Colorado canyon away from Las Vegas Valley.

However, Las Vegas gets all of its water from Lake Mead, so the city would quickly dry up. The water system has a few days worth of reserves, but after that? No more Bellagio fountain show. No more casino pools. Heck, no more water when you turned on the tap or tried to flush the toilet (and remember, there are roughly 75,000 toilets on the Las Vegas Strip alone). We wouldn't want to be around when it happens.

And it's certainly not just Las Vegans who'd suffer. Lake Mead supplies water to nearly 15 million people and irrigates more than two million acres of crop land. Southern California gets 4.4 million acre feet (compared to southern Nevada's 300,000).

All we can do is hope and pray that this is one disaster that never befalls us.

What would happen if Hoover Dam collapsed, say, in a major earthquake?

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Comments

Brent Nov-08-2019

Bellagio fountains would be fine

The Bellagio fountains use water from an underground spring of non-potable water. They would be fine.

Reno Faoro Nov-08-2019

aqua

 A what if question , but a very interesting answer on your part.Now , what is I hit the mega bucks ?????!!!!!!GO DEARBORN FORDSON  and ORVILLE HUBBARD , TOO

Kevin Rough Nov-08-2019

One thing you forget

There are dams downstream from Hoover Dam.  Davis Dam is next.  If Davis Dam weren't damaged, it would stop the water rushing further stop.  After Davis Dam, there are Parker Dam and five smaller dams before the river hits the Sea of Cortez (which is the Mexican name for the Gulf of California).

Derbycity123 Nov-08-2019

Not only problem

If there was an earthquake big enough to damage Hoover Dam Las Vegas would have more problems than being out of water.

ntm449 Nov-08-2019

Tom

Great QOD. Years ago while I was on a hard hat tour at Hoover Dam the same question was asked. The tour guide’s response was that the the rock formations on either side of the dam would collapse long before the dam itself would. Of course the water behind the dam would then flow around the dam causing massive destruction downstream. Also, while I am not an engineer, I live near Davis Dam and I have been to Parker, and I don’t think either dam would remotely contain or even slow down the surge in water released by any breach in either Hoover Dam or the surrounding natural walls.

Dave in Seattle. Nov-08-2019

FLOOD.

Worse would be a power outage caused by rushing water into power lines and sub stations.Yes,there are back up generators but for how long?Gas stations cannot pump gas and all transactions would be CASH ONLY.We all depend on electricity to be always there.Except certain parts of Kalifornia.

Kevin Lewis Nov-08-2019

Dominoes

The dams downstream would fail, one by one, as the additional water pressure weakened them and spillage overflowed the top (the spillways would never accommodate the volume). Each dam in succession would be assaulted by the water not only from Lake Mead but from Lake Mohave, etc. as well. Then after Parker, it would all spread out and inundate everything, making the lower Colorado basin uninhabitable and presenting our Mexican neighbors with a new lake the size of Tahoe.

There's a fascinating book by Marc Reisner, Cadillac Desert, that deals with this very subject and others related to dam-building in the West.

Hoover Dam was much more of a Depression-era make-work project than a cost-effective undertaking. The dam cost over 100 lives. It was said that when someone fell from the dam face, a line would form at the hiring office before the echoes of the guy's screams died out.

[email protected] Nov-08-2019

Water

That's interesting.  I always thought LAS got a lot of its water from the Las Vegas aquifer, but I guess not!

Nov-08-2019

What about the new bridge?

The question that jumped out to me because of the accompanying photo is:  Would the surging water be tall enough to wipe out that nice new bridge that sits a few hundred feet south of the dam?

Question of the Day - 08 November 2019

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