Industrial History: 1963 1.3gw Glen Canyon and Bridge Dam on Colorado River creates Lake Powell

Friday, June 2, 2023

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

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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.

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"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."

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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.

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."

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

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"