The Monticello Dam, which holds back Lake Berryessa, features a morning glory spillway. This type of spillway is basically a giant cement funnel. Rather than spilling over the dam, high waters spill into the funnel. Morning glory spillways are also known as bell-mouth spillways.
The Monticello Dam's spillway is otherwise (and affectionately) known as The Glory Hole (not to be confused with this type of glory hole). The glory hole is located about 200 feet from the dam. Water spills over its lip when the lake reaches 1,602,000 acre-feet and a reservoir elevation of 440 feet above seal level. The funnel's largest diameter is 72 feet and narrows to about 28 feet. It is designed to handle a maximum of 362,000 gallons of water per second, which occurs when the lake level rises to 15.5 feet above the level of the funnel. The last time the reservoir spilled through the glory hole was on the morning of May 18, 2006.
For obvious reasons, swimming near the glory hole is both prohibited and stupid. There are buoys strung across the lake to discourage boaters and swimmers from approaching the glory hole and the dam. Furthermore, the glory hole is well fenced off from the land. In 1997, a UC Davis graduate student was pulled into the glory hole while swimming and drowned.
The Glory Hole's Other End
During the drier months, when Lake Berryessa's water level is well below the rim of the glory hole, skateboarders and bikers sometimes use the spillway's horizontal exit as a half-pipe (or, more aptly, a full-pipe).
DanFisher offers the following advice on skating the glory hole: Unless you want to swim there, you will have to use a raft to go the last 15 feet or so. If there is a trickle of water collected at the bottom of the pipe, bring kitty litter and a push broom to keep it dry from where you're skateboarding. It's fun at night, but very very creepy!
A Davisite who is a hardcore sponsored BMX rider went to the bottom of the dam a year ago when the glory hole wasn't running, and went inside it from the bottom and had a rather intense session of riding with his buddies. One of them fell and broke an arm and has some rather nasty scars on his face now. There is videotape of the session. When asked about riding it, he said you would go up a wall for 40 feet, and then come back down like a huge vert. Intense! —StevenDaubert
The Morning Glory Spillway in times of extreme drought: September 2014
Visiting The Glory Hole
Go check out this engineering marvel! While the glory hole is not in Davis, it is cool enough and close enough that every Davisite should drive out to see it. However, if you want to see the glory hole in action (with high water), make sure to visit after a lot of rain. You can check the conditions at the Solano County Water Agency site. As mentioned at the linked URL, the lake spills at 439.74 feet.
Directions: Drive west on Covell Boulevard or Russell Boulevard. (After becoming County Road 93A, Covell eventually meets up with Russell.) In Winters, Russell becomes 128, which will take you to the top of Monticello Dam. There's a turn out right at the top of the dam where you can safely park. From Davis, it's about a half hour drive. Alternatively, you can bike up to the dam. For more information, visit the Bicycle Rides page.
2006-03-19 13:30:13 Whiskeytown Lake near Redding, CA also has a similar spillway known as "The Glory Hole" —ErikAnderson
2006-03-23 13:49:12 Damn, looks scary. I'd hate to get sucked down there... —KareemKhan
2006-03-30 17:44:51 Erik: USBR was mighty fond of this spillway/outlet arrangment, you see them on Bureau dams all over the West. :) —RussBowlus
2006-06-26 14:02:55 The Glory Hole has always terrified me. I generally try to avoid the Glory Hole. —CameronMenezes
2007-04-30 09:58:35 Haven't a couple people hit the fence and swam out to the glory hole to jump in as a means of suicide? —StevenDaubert
2011-03-18 23:00:43 Wondering how close we are to glory with all the rain we're getting this year... —CovertProfessor
2011-04-09 12:25:47 Can anyone confirm if the water level has risen high enough for this thing to be cool again? —JamesGallerani
- According to the link above, it's been at 434 feet for early June 2011, a period when we are still getting relatively heavy rains. So, we're about 6 feet from spillage. —CovertProfessor
2013-11-09 15:37:23 What happens if a tree goes down in the spillway or some other natural wastes? How they resolve if it block the entrance of the spillway? What are the hazards? —glorimartorres
It's big enough to allow a pretty massive tree to just flow thru with no problems. The floating line is also a net of sorts preventing detritus from reaching the spillway ~SD
2014-04-03 17:21:34 what's in the other side ? is it a closed end? i mean where does the water go? or does it remain in it? if it remains in it, what will happen if the tunnel is full? —farzana
- the water comes out of the bottom of the dam, if you look you can see the picture with the bmx rider in the outlet. ~SD