Not to my eye. A guess here, but I think it’s for maintenance purposes.
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.
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.
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.
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.
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.
Here’s another discussion about the Berryessa spillway from way back.
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.
I’m having trouble finding that spillway. Any help?
I couldn’t find it, either.
You can see it in Google Maps here, at the eastern side of Clarksville Rd:
https://maps.app.goo.gl/WCTqBhLxagaXQYBf9 (you might have to login and maybe turn on “3D” mode for a better view)
There’s also a user-submitted video.
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.
It doesn’t look like one to me either. It’s still a scary wet death tube though.
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!
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.
Really cool side find. Thanks for sharing!
Did anyone think to check the bottom of a certain spillway…? 
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.
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.
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.
Looks extremely dangerous and undoubtedly fatal to anyone foolish enough to cut through the fence with the idea of taking a closer look.