# Have you ever seen a bell-mouth spillway? (aka a “Glory Hole”)

**URL:** <https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480>\
**Category:** Miscellaneous and Personal Stuff I Must Share\
**Created:** [April 1, 2025, 11:43pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480 "2025-04-01T23:43:01Z")\
**Posts on this page:** 20\
**Page:** 2

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**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\
**Post date:** [April 2, 2025, 4:48pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/21 "2025-04-02T16:48:51Z")

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Not to my eye. A guess here, but I think it’s for maintenance purposes.

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**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\
**Post date:** [April 2, 2025, 4:53pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/22 "2025-04-02T16:53:12Z")

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> [@blondebear](#):
>
> I went to Lake Berryessa a few years ago to see this. The water level was just barely enough to be flowing into the spillway so it wasn’t as cool looking as I had hoped. As I remember it was kind of tough to get a good picture from the side of the road…the drone shots are the way to go.

It’s a bit of a drive from the Bay Area, but yesterday I was driving back to SF from Sacramento and it wasn’t too ridiculously far out of the way.

It’s nice that they put it near the highway. You can get decent enough views of it from the road. The drone shots I posted were from someone who brought his drone. I’m glad he brought it. But you don’t need a drone. It’s close enough to see and hear from the road nice enough.

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**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\
**Post date:** [April 2, 2025, 4:55pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/23 "2025-04-02T16:55:28Z")

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Not quite the same thing, but debris basins around Los Angeles have vertical pipes to prevent being overtopped. Debris basins are dams intended to slow the flow of water and debris runoff down narrow mountain valleys. They’re dry except when actively retaining runoff, but you’d see a similar open maw when the basin is full.

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**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\
**Post date:** [April 2, 2025, 5:32pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/24 "2025-04-02T17:32:41Z")

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> [@solost](#):
>
> I’ve morbidly wondered in the past what would happen if one fell into a bell-mouth spillway like the one in the OP. It sure looks like it would be pretty darn fatal, but, depending on the diameter of the pipe once the funnel narrows, length of transit, height of exit and depth of water you fall into, maybe it wouldn’t be so bad. Almost like a waterslide at [Action Park](https://www.history.com/articles/the-rise-and-fall-of-action-park-new-jerseys-most-dangerous-water-park)!

The experience with ones having a turbine near the bottom would probably be about like being cuisinarted. Not long after having been drowned.

Admittedly, most examples of this design are overflow prevention drains, not power production intakes.

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**Author:** ![WildaBeast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wildabeast/32/6_2.png) [@WildaBeast](https://boards.straightdope.com/u/WildaBeast)\
**Post date:** [April 2, 2025, 5:59pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/25 "2025-04-02T17:59:22Z")

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The small lake at the Boy Scout camp I went to in my teens had something that was similar in concept to a bell-mouth spillway. It was made from a steel culvert that was oriented vertically, which the overflow water drained into and exited through a culvert at the bottom of the dam. This one had a cap on top with steel mesh around it, so you could actually safely paddle up to it in a canoe.

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**Author:** ![Twoflower](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/twoflower/32/22_2.png) [@Twoflower](https://boards.straightdope.com/u/Twoflower)\
**Post date:** [April 2, 2025, 6:00pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/26 "2025-04-02T18:00:00Z")

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As a north bay resident, I visited Berryessa many times in my younger years. I have childhood memories of taking a “Sunday drive” specifically to go see the glory hole. I see on Wikipedia that it first spilled in 1963, so I’m pretty sure I witnessed that first event.

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**Author:** ![Twoflower](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/twoflower/32/22_2.png) [@Twoflower](https://boards.straightdope.com/u/Twoflower)\
**Post date:** [April 2, 2025, 6:40pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/27 "2025-04-02T18:40:04Z")

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Here’s another discussion about the Berryessa spillway from way back.

> [@ID this picture...please](https://boards.straightdope.com/t/id-this-picture-please/374495):
>
> Posted on [this thread](http://forums.fark.com/cgi/fark/comments.pl?IDLink=2313374) at [Fark.com](http://Fark.com) But you can just see the picture [here](http://x02.xanga.com/d12b24546673140803280/b27814498.jpg) . What is this? Is it photoshopped? Is it real? Note the warning floaters in the background. For some reason they give the photo credibility. Or did someone just wake the Krakken? Thanks dopers!

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**Author:** ![Lancia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lancia/32/17174_2.png) [@Lancia](https://boards.straightdope.com/u/Lancia)\
**Post date:** [April 2, 2025, 6:46pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/28 "2025-04-02T18:46:15Z")

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Someone flew a drone down the (dry) gloryhole and out the downstream end. It gives me the willies just watching it in my phone screen.

[![](https://img.youtube.com/vi/4TCWs-QfJV8/maxresdefault.jpg "Flying The Drone Inside of The Glory Hole") ](https://www.youtube.com/watch?v=4TCWs-QfJV8)

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**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\
**Post date:** [April 2, 2025, 6:58pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/29 "2025-04-02T18:58:52Z")

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> [@CalMeacham](#):
>
> There’s one of these at the dam at Grovers Mill in West Windsor, New Jersey.
> 
> And if that sounds familiar – yes, this is the place where the Martian cylinder landed in the infamous Orson Welles 1938 Halloween _War of the Worlds_ broadcast. There’s a monument there now, erected on the 50th anniversary of the event. The Mill building is still there, and so is the odd water tower that was supposedly shot at because someone thought it was a Martian tripod.
> 
> [Grovers Mill, New Jersey - Wikipedia](https://en.wikipedia.org/wiki/Grovers_Mill,_New_Jersey)
> 
> [Grovers Mill, New Jersey - Wikipedia](https://en.wikipedia.org/wiki/Grovers_Mill,_New_Jersey#/media/File:Landingsite_statue.JPG)
> 
> Never heard it called a “Glory Hole” before. That’s playing with fire.

I’m having trouble finding that spillway. Any help?

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**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\
**Post date:** [April 2, 2025, 7:19pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/30 "2025-04-02T19:19:29Z")

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> [@Bullitt](#):
>
> I’m having trouble finding that spillway. Any help?

I couldn’t find it, either.

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**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\
**Post date:** [April 2, 2025, 7:25pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/31 "2025-04-02T19:25:50Z")

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> [@Bullitt](#):
>
> I’m having trouble finding that spillway. Any help?

You can see it in Google Maps here, at the eastern side of Clarksville Rd:  
[https://maps.app.goo.gl/WCTqBhLxagaXQYBf9](https://maps.app.goo.gl/WCTqBhLxagaXQYBf9) (you might have to login and maybe turn on “3D” mode for a better view)

[![](https://i.imgur.com/6B3CMCU.png) ](https://i.imgur.com/6B3CMCU.png)

There’s also a [user-submitted video](https://www.google.com/maps/place/Grovers+Mill+Pond/@40.3114611,-74.6060042,3a,75y,90t/data=!3m8!1e5!3m6!1sCIHM0ogKEICAgIDc4JDG9AE!2e10!3e10!6shttps:%2F%2Flh3.googleusercontent.com%2Fgps-cs-s%2FAB5caB_5SwybI5fYkpT1hmJSOxqnoHU1erWtAEytyHVm6a0mPMsZZqOZDvDcqh1iCkc28tU7uUJe69EjhMOMDKDw7H449WQ7uJcY9eK1RBBolH2W9AD5quZe6jyfl7fRcMIcZTsoThboQA%3Dw203-h114-k-no!7i1920!8i1080!4m7!3m6!1s0x89c3e0bb3f9d9447:0xade3d9accae46580!8m2!3d40.3114611!4d-74.6060042!10e5!16s%2Fg%2F1232jdrmr?entry=ttu&g_ep=EgoyMDI1MDMzMC4wIKXMDSoASAFQAw%3D%3D).

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**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\
**Post date:** [April 2, 2025, 8:18pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/32 "2025-04-02T20:18:28Z")

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Thanks. I did spot that on the map, but did not think that was the glory hole spillway so I tried some other searches around those terms but struck out. Thanks for the user video. IANAE but to be a bit technical about it, I’m not certain that is a bell-mouth spillway.

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**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\
**Post date:** [April 2, 2025, 8:19pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/33 "2025-04-02T20:19:59Z")

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It doesn’t look like one to me either. It’s still a scary wet death tube though.

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**Author:** ![Oly](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/oly/32/8255_2.png) [@Oly](https://boards.straightdope.com/u/Oly)\
**Post date:** [April 3, 2025, 2:03am UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/34 "2025-04-03T02:03:11Z")

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Wow! It’s like going into hyperspace. I really like the graffiti on the inside of the tube. It’s like a modern day Lascaux.

@ftg Good to hear the lake will be up this year. I haven’t seen the Glory Hole flowing in a long time, and I’m planning a trip to the lake this summer with my brother. We’re going there to visit the spot in the sage brush hills above the river where we deposited the cremains of our dad and older brother. It’s been a few years since then. Someday I might get put there myself. But not for a while😁 But if that does happen, maybe some of my particles will wash down into the river and take that trip through the Glory Hole!

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**Author:** ![markn\_1](https://avatars.discourse-cdn.com/v4/letter/m/f9ae1b/32.png) [@markn\_1](https://boards.straightdope.com/u/markn_1)\
**Post date:** [April 3, 2025, 4:27pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/35 "2025-04-03T16:27:39Z")

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I recognized “Owyhee” as an older spelling of “Hawai’i” and wondered what connection there could be between the Pacific islands and a dam in Oregon. It turns out the Owyhee River was named for three native Hawai’ans employed by the North West Company to explore the Pacific Northwest wilderness, who disappeared on an expedition near the river in 1819.

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**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\
**Post date:** [April 3, 2025, 7:36pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/36 "2025-04-03T19:36:33Z")

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> [@markn\_1](#):
>
> I recognized “Owyhee” as an older spelling of “Hawai’i” and wondered what connection there could be between the Pacific islands and a dam in Oregon.

Really cool side find. Thanks for sharing!

> [@markn\_1](#):
>
> disappeared on an expedition near the river in 1819

Did anyone think to check the bottom of a certain spillway…? 😉

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**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:** [April 3, 2025, 11:38pm UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/37 "2025-04-03T23:38:50Z")

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If you needed cheap labor in the West in those days, importing people from the East Coast wasn’t the best idea. But people from Hawaii were more readily brought in. Over time, so many were taken to the US West Coast (esp. California) that workers for the new plantations in Hawaii became scarce. So workers from Japan were brought in and became a major ethnic group.

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**Author:** ![scudsucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/scudsucker/32/14101_2.png) [@scudsucker](https://boards.straightdope.com/u/scudsucker)\
**Post date:** [April 4, 2025, 10:43am UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/38 "2025-04-04T10:43:35Z")

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> [@solost](#):
>
> It sure looks like it would be pretty darn fatal, but, depending on the diameter of the pipe once the funnel narrows, length of transit, height of exit and depth of water you fall into, maybe it wouldn’t be so bad.

In my case, fatal. 10m fall. No pool below, just bare concrete (ok, wet concrete).

To answer your other questions: the funnel was roughly the same diameter as the egress tunnel. Let’s say 10m. The tunnel was about 100m long. Depth of water in the tunnel, maybe 30cm, but obviously over-engineered for floods.

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**Author:** ![MandaJo](https://avatars.discourse-cdn.com/v4/letter/m/ac91a4/32.png) [@MandaJo](https://boards.straightdope.com/u/MandaJo)\
**Post date:** [April 4, 2025, 11:11am UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/39 "2025-04-04T11:11:41Z")

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I know two parks in Dallas that have one in the duck pond. Lakeside Park in Turtle Creek (at St Johns and Fitzhugh) and Lake Cliff Park in Oak Cliff off Colorado.

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**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\
**Post date:** [April 4, 2025, 11:45am UTC](https://boards.straightdope.com/t/have-you-ever-seen-a-bell-mouth-spillway-aka-a-glory-hole/1016480/40 "2025-04-04T11:45:45Z")

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> [@LSLGuy](#):
>
> Dry or wet, it’s a frankly horrifying sight; this gigantic concrete maw like an enormous trombone mouth that leads down at a stupid-steep angle to the very depths of the Earth.

Looks extremely dangerous and undoubtedly fatal to anyone foolish enough to cut through the fence with the idea of taking a closer look.

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