1963 1.3gw Glen Canyon Dam, Bridge and Lake Powell on Colorado River creates Lake Powell

(Satellite)

usbr
Glen Canyon Dam and all four jet tubes open releasing water for high-flow experiment - Mar 5, 2008.
The dam is 710' (216m) high. (Hoover Dam is 726' (221m)). Eight generators have a total capacity of 1,320mw. Lake Powell began filling on Mar 13,1963, and the filling completed on Jun 22, 1980 with a capacity over 25 million acre-feet of water.

 

usbr_projects
"The concrete arch dam has a crest length of 1,560 feet and contains 4,901,000 cubic yards of concrete. Thickness of the dam at the crest is 25 feet, and the maximum base thickness is 300 feet....Each spillway tunnel reduces in size from 48 to 41 feet in diameter. The combined spillway discharge capacity is 208,000 cubic feet per second at an elevation of 3,700.0 ft. The outlet works near the left abutment of the dam consist of four 96-inch-diameter pipes. Each outlet is controlled by one 96-inch-ring follower gate and one 96-inch hollow-jet valve. The combined river outlet works capacity is 15,000 cubic feet per second."

 

Visit Page Arizona posted
Let’s flash back to the 1960s — this photo from November 16, 1961, was taken by the Bureau of Reclamation and shows the progression of construction on the Glen Canyon Dam. Water starts to form what will later be Lake Powell, as debris begins to gather at the bottom of the dam.

Dan Gilbert commented on the above post

The dam under construction.

Photo taken from the temporary suspension bridge

in 1960.

azcentral posted
Finished in 1963, Glen Canyon Dam in Arizona remains at the center of an environmental and cultural controversy. 
bit.ly/4kqLBe4 [paywall]

usbr, History tab

usbr, History tab

 

Bridges Now and Then posted
Arizona's Glen Canyon Dam Bridge, September, 1960. (Found on Reddit)

 

Vintage Las Vegas posted

Glen Canyon Dam, June 1983, when sheets of plywood were all that kept the dam from overflowing. 

Following a long winter and warm spring, inflows exceeded normal levels and filled Lake Powell. Bureau of Reclamation managers opened penstocks to full release. When inflow rates continued to rise, they also opened the river outlet works. When the reservoir still continued to rise, the emergency overflow spillways were put into use. From the spillway tunnels came unknown rumblings, and large boulders being ejected into the river. To understand what was happening the managers needed to stop the flow into the spillways. Plywood flashboards were installed on top of the spillway gates, allowing reservoir water to rise 4 feet. They discovered the phenomenon of cavitation was blowing holes into the tunnels. Despite the potential for greater damage the water would soon need to flow again. 

Downstream, at Hoover Dam, the excess flows had already filled Lake Mead reservoir. The Colorado river would soon top the spillway gates and flow uninterrupted for more than two months. 

Last summer when we posted about the 40th anniversary Colorado River flooding, someone in comments recommended the book The Emerald Mile (2013). Whomever that was, thank you, great book. 

Photo from Bureau of Reclamation

 

Aaron Dennis commented on the above post
The bigger issue was when they opened the spillway gates, a design flaw caused cavitation in the spillway tunnels that heavily eroded the concrete lined tunnels which then caused erosion to the soft sandstone that the dam was built against. It could have causes a complete failure of the dam so they had to greatly reduce or even stop the flows through the spillways.

Colorado River Basin posted four photos with the comment:

In 1983, three years after Lake Powell first filled, an unusually long winter created a lot of heavy snowpack across the Colorado River Basin. That led to increased runoff that spring and summer, and on July 14-15, 1983, Lake Powell reached 3,708.34 feet in elevation, a level that has not been exceeded since. Inflows to Lake Powell reached 120,000 cfs while releases topped 92,000 cfs. As the reservoir level increased, plywood flashboards were installed on top of the spillway gates, which allowed the reservoir water to rise an additional 4 feet without increasing releases. Modifications and repairs to the spillway were still being completed when the water levels rose again to dangerous elevations in 1984, but decreased as the summer progressed.

More than 40 years later, we’d sure love to see some of that water up against the dam again!

📸Photos of the bypass tubes and spillways being used in July 1983, and of the plywood flashboards installed on top of the spillway gates.

Alan Stewart: I remember Bullfrog Marina store was surrounded with sandbags!

Marcia Netzley: Alan Stewart, we remember those sandbags too as my family had rented a houseboat out of Bullfrog that year. There was a lot of water!

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Until the Winter of 2023, the Colorado River watershed had a drought for years.

NASA Earth posted
Lake Powell, the 2nd-largest reservoir in the U.S., now stands at 26% of capacity, its lowest point since being filled in the mid-60s. On Aug. 22, the surface elevation was 3,533.3 feet, more than 166 feet below full pool. These natural-color Landsat images show the lake in summer 2017 vs. summer 2022.
https://go.nasa.gov/3Co7DKy
Dave Durham shared

Route 66 Road Relics posted four photos with the comment: "Glen Canyon Dam in Page Arizona."

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Derek Brust commented on the post by Route 66 Road Relics

 Kasia Suszyna-Miturska commented on the post by Route 66 Road Relics

 Benoit Lamontagne commented on the post by Route 66 Road Relics

 Benoit Lamontagne commented on the post by Route 66 Road Relics

 Benoit Lamontagne commented on the post by Route 66 Road Relics

ReviewJournal, 2004 photo by Laura Rauch
They released water from Apr 24-30,2023, with flows up to 39,500cfs. The reservoir should drop 4.5' (1.4m). Normal releases are 8-25kcfs. "The aim is to have the water push sediment onto the beaches and sandbars along the river, rebuilding them and rendering them more usable for camping."

The Winter of 2023 left a big snow pack so they have been running high-flow experiments to make room for it to melt and to replenish Lake Mead.

Lake Powell was down to 26% of its capacity at the beginning of 2023 and within 32' (10m) of its minimum power pool. [latimes]

NASA, Apr 24, 2023
"In addition to replenishing shrinking sandbars used by campers and rafters, ecologists expect the simulated flood will preserve and restore habitat for key invertebrates and various species of fish and plant life. Researchers also expect the flood to help protect sensitive archaeological structures and artifacts exposed by erosion."

Miguel Nuñez posted four photos with the comment: "One of my favorite bridges to 🚶‍♂️    Page Arizona USA"

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4:32 video @ 0:19

High-flow experiments have caused cavitation and damage in the outlet pipes.

The penstocks can pass 33.2kcfs, the river outlet works can pass 15kcfs and the spillways can pass 276kcfs.

8:03 video

This was basically an advertisement for IH trucks.

27:16 video @ 16:48

Nov 5, 2026:

Chase Thomason posted

🚨 LAKE POWELL IS NOW HIGHER THAN IT WAS IN 2022!

What we’re witnessing at Lake Powell is becoming increasingly unusual. The reservoir has climbed an incredible 19 FEET since its mid-September low, and the water continues to pour in following weeks of exceptional rainfall across the Four Corners and San Juan River watershed.

Take a look at the graph. It really puts this into perspective. Lake Powell has now moved above its 2022 levels, despite typically seeing reservoir levels decline during the fall. These kinds of gains this time of year are anything but ordinary.

A few important numbers:

📈 19 feet: Rise since the mid-September low.

📊 164 feet: Still below full pool. We have a long way to go.

🌊 7%: The estimated contribution from Flaming Gorge releases to the recent rise.

That last number is important. Flaming Gorge has been releasing additional water into the Colorado River system for months, but it accounts for only about 7% of this recent increase. The overwhelming majority of the rise is being driven by natural runoff from the extraordinary precipitation across the Four Corners, particularly the San Juan River basin.

And remember, this isn’t just rain falling directly into Lake Powell. Enormous amounts of water are moving through tributaries, rivers and drainage basins. That runoff takes time to make its way downstream and into the reservoir, meaning Powell can continue rising even after the heaviest precipitation has ended.

[These El Nino rainstorms have cause severe flooding in some areas. For example: Pagosa Springs.]

Chase Thomason posted

LAKE POWELL IS SURGING! 17 INCHES IN JUST 24 HOURS. 🤯

Another incredible update from Lake Powell. The reservoir has climbed 19 FEET since hitting its lowest level in mid-September. And the water just keeps coming.

Here’s what’s happening:

🌊 Massive inflows: Recent rainfall across the Four Corners has generated tremendous runoff into the Colorado River system. The San Juan River has been a major contributor, accounting for an unusually large share of the water flowing into Lake Powell.

🌧️ Flooding is driving the rise: Some areas of southeastern Utah and the Four Corners have experienced catastrophic flooding. That floodwater doesn’t disappear once the rain stops. It continues moving downstream through the San Juan River drainage and eventually makes its way into Lake Powell. We’re still seeing that runoff work its way through the system.

💧 How much water are we talking about? A 19-foot rise represents approximately 1.1 million acre-feet of additional water, or roughly 360 billion gallons. That’s an extraordinary amount of water entering the reservoir in a relatively short period.

And we’re not finished.

Based on the continued runoff and water still working its way downstream, Lake Powell could climb another several feet. We could be looking at a total rise of 23-25 FEET from its September low by the time this event winds down next week.

Think about that for a moment. We’re seeing a massive reservoir gain tens of feet in the middle of FALL, not during the traditional spring snowmelt season. This is an exceptionally unusual and potentially historic fall runoff event for the Colorado River system.

One important perspective: This is tremendous news for Lake Powell, but it doesn’t erase the long-term water challenges facing the Colorado River Basin. The lake is still well below full pool.

Still, what we’re witnessing right now is remarkable. And I’ll continue tracking the numbers as more of this water makes its way into the reservoir. Mother Nature is delivering an incredible amount of water to Lake Powell.