# If everyone on earth suddenly disappeared, what would happen to Boulder (Hoover) dam? **URL:** \ **Category:** Factual Questions\ **Created:** [May 23, 2009, 9:11pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422 "2009-05-23T21:11:57Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [May 23, 2009, 9:11pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/1 "2009-05-23T21:11:57Z")
Of course eventually the generators would freeze up (due to the lack of lubrication?) but what would the water do (go) after that? Would the ultimate fate of the dam be destruction? What would be the effect down below? ---
**Author:** ![Captain\_Amazing](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Captain\_Amazing](https://boards.straightdope.com/u/Captain_Amazing)\ **Post date:** [May 23, 2009, 9:31pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/2 "2009-05-23T21:31:05Z")
The water would keep rising above the dam, until it topped the dam, and then it would overflow. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [May 23, 2009, 9:35pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/3 "2009-05-23T21:35:10Z")
Of course something bad would eventually happen to the dam to cause its destruction - overtopping, earthquake, cracking leading to rupture… … after which there would be one hell of a flood rushing downstream causing horrific destruction. ---
**Author:** ![Jragon](https://avatars.discourse-cdn.com/v4/letter/j/e19b73/32.png) [@Jragon](https://boards.straightdope.com/u/Jragon)\ **Post date:** [May 23, 2009, 9:38pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/4 "2009-05-23T21:38:33Z")
You weren’t watching the rerun of Life After People last night were you? I’m guessing it would probably top over the dam and then gradually crack and crumble and erode until the “dam” isn’t quite that anymore. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [May 23, 2009, 9:39pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/5 "2009-05-23T21:39:52Z")
The History Channel documentary _Life After People_, which pretty much dealt with the consequences of the whole of humanity suddenly disappearing from the planet, came to the conclusion that the Hoover Dam would only stop generating power after about a year, when mussels clog up the coolant pipes. As a structure, it might still stand up to 10,000 years in the future. The [wiki article](http://en.wikipedia.org/wiki/Life_After_People) has a rundown of the proposed effects of mankind’s disappearance. ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [May 23, 2009, 10:02pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/6 "2009-05-23T22:02:12Z")
Thanks all. But I’m thinking what if the water (with all its pressure) gets into the generator room through a broken seal or valve? Would the whole structure be compromised? ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [May 23, 2009, 10:08pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/7 "2009-05-23T22:08:11Z")
Don’t recall that this book addressed the question of Hoover Dam specifically, but it’s a dammed (and damned) good read: [The World Without Us - Wikipedia](http://en.wikipedia.org/wiki/The_World_Without_Us) ---
**Author:** ![Early\_Out](https://avatars.discourse-cdn.com/v4/letter/e/6f9a4e/32.png) [@Early\_Out](https://boards.straightdope.com/u/Early_Out)\ **Post date:** [May 23, 2009, 10:37pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/8 "2009-05-23T22:37:44Z")
> [@Jake](#): > > Thanks all. But I’m thinking what if the water (with all its pressure) gets into the generator room through a broken seal or valve? Would the whole structure be compromised? The generators are housed in buildings that sit in front of the dam - they’re not part of the dam’s structure. Those buildings could be swept away completely without having any effect on the dam itself. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [May 23, 2009, 10:40pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/9 "2009-05-23T22:40:00Z")
> [@Half\_Man\_Half\_Wit](#): > > As a structure, it might still stand up to 10,000 years in the future. They’ve had trouble with erosion in [Hoover dam’s over-spill tunnels](http://www.panoramio.com/photo/15777974), If the water gets too frisky inside them, it’ll rip out the concrete lining\*. If that happens, it’s a crapshoot as to whether the tunnel widens and water bypasses or undermines the dam, or the tunnel collapses and water overtops the dam. Two of those three scenarios result in a pile of rubble where the dam was in far less than 10,000 years. * * * \*There are pictures of the aftermath of this happening somewhere on the internet. I can’t find them today. ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [May 23, 2009, 10:45pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/10 "2009-05-23T22:45:26Z")
> [@Captain\_Amazing](#): > > The water would keep rising above the dam, until it topped the dam, and then it would overflow. Once the intake pipes were clogged, water would rise until it reached the top of the two spillways and poured down them, exiting downstream from the dam. This [enormous diagram](http://upload.wikimedia.org/wikipedia/commons/5/56/Hoover_Dam_Diagram.jpg) shows how the spillway on the Arizona side works; the water would overtop the side of the spillway and flow through the tunnel out into the Colorado River hundreds of feet downstream. [Here](http://farm4.static.flickr.com/3159/2794869839_1aca72671e.jpg?v=0) is a smaller version of the same diagram, in case you don’t want to download a huge picture. And [here](http://www.lauraonline.co.uk/01-Diagram-of-the-Dam.jpg) is a neat overhead diagram that shows the relative locations of the Nevada and Arizona spillways and how far each goes. Note that the spillways were built to use two of the four 50-foot-wide diversion tunnels that were used to divert the river whlie the dam was being built; I presume, but don’t know for sure, that the two remaining tunnels could still hande the entire flow of the Colorado River. If not, then the water level would continue to rise until it overtopped the dam as well. Of course, you also have to take into consideration what would happen to the Glen Canyon Dam and the other dams upriver from Lake Mead. If the Glen Canyon dam failed, Lake Powell would start emptying into Lake Mead; I’m not sure how that would affect Hoover Dam. Anybody know? ETA: **Squink** ’s information adds another fascinating question; how long would the spillways last if they were in use continuously, and had to handle the full flow of the river, or a flood from Lake Powell? Probably not very long. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [May 23, 2009, 10:49pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/11 "2009-05-23T22:49:22Z")
> [@Squink](#): > > They’ve had trouble with erosion in [Hoover dam’s over-spill tunnels](http://www.panoramio.com/photo/15777974), If the water gets too frisky inside them, it’ll rip out the concrete lining\*. If that happens, it’s a crapshoot as to whether the tunnel widens and water bypasses or undermines the dam, or the tunnel collapses and water overtops the dam. > Two of those three scenarios result in a pile of rubble where the dam was in far less than 10,000 years. I hope it didn’t appear that I was claiming any expertise, because I have none; I was merely repeating claims from the documentary. ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 23, 2009, 10:51pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/12 "2009-05-23T22:51:25Z")
Regarding the dam failure, it is my understanding that the USBR has developed inundation mapping which shows the area expected to be flooded in the case of a dam breach. IIRC, they are classified and not available to the general public ATM. ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 23, 2009, 10:57pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/13 "2009-05-23T22:57:07Z")
> [@chorpler](#): > > If the Glen Canyon dam failed, Lake Powell would start emptying into Lake Mead; I’m not sure how that would affect Hoover Dam. Anybody know? According to [this](http://www.riversimulator.org/Resources/USBR/GCDDamFailure.pdf) report, Hoover Dam would be overtopped. It kind of dances around the question of whether or not failure of HD would occur. To be fair, that wasn’t really the scope of the study. ---
**Author:** ![chorpler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chorpler/32/2888_2.png) [@chorpler](https://boards.straightdope.com/u/chorpler)\ **Post date:** [May 23, 2009, 11:17pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/14 "2009-05-23T23:17:49Z")
> [@NinetyWt](#): > > According to [this](http://www.riversimulator.org/Resources/USBR/GCDDamFailure.pdf) report, Hoover Dam would be overtopped. It kind of dances around the question of whether or not failure of HD would occur. To be fair, that wasn’t really the scope of the study. Awesome. This is a fascinating read. ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [May 23, 2009, 11:45pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/15 "2009-05-23T23:45:59Z")
Oftentimes we find that a downstream dam is capable of passing the breach flow from an upstream dam without overtopping. I was a little surprised to read that it wasn’t the case for those two. ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [May 24, 2009, 6:04pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/16 "2009-05-24T18:04:04Z")
Thanks, all. For some reason I was thinking that the powerhouse was inside the dam instead of being outside at the base. The charts and diagrams were great, and I learned a lot. ---
**Author:** ![AlsoNamedBort](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alsonamedbort/32/3213_2.png) [@AlsoNamedBort](https://boards.straightdope.com/u/AlsoNamedBort)\ **Post date:** [May 24, 2009, 6:06pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/17 "2009-05-24T18:06:42Z")
Once it get’s overtopped, what would happen then? Would it basically just be a giant waterfall? Would this lead to the dam’s destruction faster? ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [May 24, 2009, 6:42pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/18 "2009-05-24T18:42:55Z")
> [@AlsoNamedBort](#): > > Once it get’s overtopped, what would happen then? Would it basically just be a giant waterfall? Would this lead to the dam’s destruction faster? The real life dams that have been overtopped that I have read about all quickly failed. (But a lot of those are 19th century dams.) I don’t think Hoover would last long at all. ---
**Author:** ![Early\_Out](https://avatars.discourse-cdn.com/v4/letter/e/6f9a4e/32.png) [@Early\_Out](https://boards.straightdope.com/u/Early_Out)\ **Post date:** [May 24, 2009, 7:06pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/19 "2009-05-24T19:06:47Z")
> [@ftg](#): > > The real life dams that have been overtopped that I have read about all quickly failed. (But a lot of those are 19th century dams.) I don’t think Hoover would last long at all. Those were probably all earthen dams. Hoover is concrete, as wide at the base (I mean front to back, not side to side) as it is tall, so I don’t think the cascading water would erode the face of the dam to any appreciable degree. ---
**Author:** ![Markxxx](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@Markxxx](https://boards.straightdope.com/u/Markxxx)\ **Post date:** [May 24, 2009, 8:44pm UTC](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422/20 "2009-05-24T20:44:12Z")
Gracie Allen) That’s the government for you. Always doing thing the hard way George Burns) The hard way? Gracie) Yes, changing the name of Boulder Dam To Hoover Dam George) They did that to honor Herbert Hoover. Gracie) That’s what I mean, instead of changing the name of that great big dam, it would’ve been much easier to change the name of a little man. George) Oh I see…Change Herbert Hoover’s name to Hoover Boulder Gracie) See, even you could get it. …And now back to the question in hand… [Next page](https://boards.straightdope.com/t/if-everyone-on-earth-suddenly-disappeared-what-would-happen-to-boulder-hoover-dam/497422.md?page=2)