Federal officials consider overhauling Glen Canyon Dam
The Colorado River’s drying up has left Lake Powell, the country’s second-largest reservoir, at just 23% of its capacity, the lowest since it was filled in the 1960s.
With the reservoir now just 32 feet from the “minimum power pool” — the point at which Glen Canyon Dam would stop generating electricity for six states — federal officials are exploring the possibility of overhauling the dam so it can continue generating electricity can and release of water at a critically low level.
A preliminary analysis of possible changes to the dam came during a virtual meeting of the Federal Bureau of Reclamation, which is also reviewing options to avert a water supply collapse along the river. These new discussions about the dam’s upgrade reflect growing concerns among federal officials about how climate change is contributing to the Colorado River’s reduced discharges and how declining reservoirs could force major changes in dam management in the years to come.
One of the immediate concerns is the risk of the reservoir falling below the dam’s power generation threshold. In this case, the water would only flow through four 8-foot-wide bypass tubes called outlet works, creating a bottleneck with reduced water release capacity.
“There is an acknowledgment now as never before that the dam will not be suitable for 21st century hydrology,” said Kyle Roerink, executive director of the environmental group Great Basin Water Network, who was listening to the meeting. “They don’t sugarcoat that things need to change there, and they need to change pretty quickly.”
The Feb. 7 meeting included dozens of water managers, electric utility officials, state officials and others. They discussed such proposals as penetrating the dam’s concrete to make new lower-level inlets, installing a new or reconfigured power station, and tunneling a shaft around both sides of the dam to form a power station, among others.
The Home Office declined a request for an interview, but spokesman Tyler Cherry said in an email that the briefing is part of broader discussions with state officials, tribal leaders, water managers and others “to commit to our work to improve and protect short-term sustainability.” of the Colorado River System and the resilience of the American West to a changing climate.”
Roerink and two others listening to the webinar told The Times that cost estimates for several alternatives ranged from $500 million to $3 billion. The agency needs congressional approval and must conduct an environmental review to analyze options.
The Bureau of Reclamation presentation, made by regional energy manager Nick Williams, included some additional alternatives that would not require major structural changes to the dam. These options included adapting operations to maximize power generation when reservoirs are low, investigating ways to use the existing intakes when water levels are lower, and offsetting the loss of hydropower with investments in solar or wind power.
Glen Canyon Dam is 710 feet tall and anchored to the reddish sandstone walls of the canyon in northern Arizona, about 320 miles upstream from Lake Mead, the nation’s largest reservoir. The dam has been controversial since its inception, with environmental activists and others arguing the reservoir was unnecessary and had destroyed the canyon’s pristine ecosystem.
Lake Powell and Lake Mead have receded for the past 23 years during the worst drought in centuries. Federal officials have been trying to increase Powell levels in recent months by reducing the amount of water they release downstream pending the arrival of the spring runoff. They have said they may need to further reduce water delivery.
A key concern is that if the water falls below the minimum performance pool — 3,490 feet above sea level under current operating regulations — the main intakes would have to be closed and water would instead flow through the dam’s lower bypass tubes. Due to the reduced capacity of these tubes, this could result in less water flowing downstream, shrinking the flow of the Grand Canyon river and accelerating Lake Mead’s decline toward the “dead pool” — the point at which no more water flows through the Hoover River. Dam would flow to Arizona, California and Mexico.
Federal officials prepared the first studies of Glen Canyon Dam alternatives, using $2 million that the Bureau of Reclamation secured as part of $200 million for drought response measures.
According to a slide presentation shown at the meeting, officials see potential dangers in some of the six alternatives. Piercing the dam’s concrete to create new low- or mid-level inlets, for example, would pose an “increased risk of intrusion through the dam,” the presentation said.
They also describe risks from a possible “vortex formation” or the formation of eddies over horizontal inlets when the water level falls. Their formation could cause damage if air is drawn into the system. The presentation states that an alternative would be to lower the minimum power pool limit and possibly install structures at the inlets to suppress whirlpools, but this still would not allow the water level to get much lower.
One of the possible solutions involves installing a new power plant that generates electricity using water flowing out of the bypass tubes, or a similar approach using the existing infrastructure. Another would involve digging a tunnel on the left or right side of the dam and installing a power station underground or in the river bed.
Other options include changing operations at both Glen Canyon and Hoover Dams “to maximize power generation in low-flow conditions using existing infrastructure.”
“Each of the options is going to be very expensive and very time consuming,” said Leslie James, executive director of Colorado River Energy Distributors Assn., who attended the meeting.
James commended the Bureau of Reclamation for “starting processes to consider structural options like this.”
“The way I look at what they’re doing here is that they start early and at least evaluate everything they can to see and see what’s feasible,” James said. She said she hopes Congress will provide the funding needed to ensure power continues to flow from Glen Canyon Dam given “how important hydropower is to entire communities.”
Her association represents nonprofit utilities that purchase electricity produced by Glen Canyon Dam and other dams that are part of the Colorado River Storage Project. The association includes members in Arizona, Colorado, Nevada, Utah, New Mexico and Wyoming. The utilities provide electricity to cities, rural areas, irrigation districts and tribal communities.
Power from the dam has long been a vital source of energy, although its output has declined dramatically in recent years as Lake Powell has receded. In fiscal 2022, Glen Canyon Dam generated 2,591 gigawatt hours of electricity, enough to power more than 240,000 average homes for a year.
James said electric utilities across the region have had to offset reduced hydropower by turning to other, more expensive sources.
“It’s a really challenging time,” James said. “And it’s ultimately the people in these communities that are being impacted by higher utility bills.”
Lake Powell’s level is expected to rise this spring due to runoff from the above-average snowpack in the Rocky Mountains. However, this rise in water levels is expected to have limited impact on the deep water deficit that has accumulated over more than two decades.
And over the long term, scientific research shows that warming and drying out will continue to put severe strain on the river.
Scientists have found that about half of the decline in river flow since 2000 is due to higher temperatures, that climate change is driving the Southwest’s drying out, and that for every additional 1 degree Celsius (1.8 degrees Fahrenheit) of warming, the river recedes average flow is likely to drop by about 9%.
Environmental activists have been urging the federal government for years to consider draining Lake Powell, decommissioning the dam and storing the water downstream in Lake Mead.
Activists who heard the Bureau of Reclamation’s presentation said they welcome the agency’s investigation into the problems at Glen Canyon Dam but would prefer a broader analysis that evaluates other options, including draining the reservoir.
In a report last year, Roerink’s Great Basin Water Network and two other groups warned that “the antiquated sanitation system at Glen Canyon Dam poses a liability to Colorado River Basin water users, who quickly find themselves in legal jeopardy and water supply shortages.” could”.
“The Bureau admits that the dam is a burden,” Roerink said. “From my point of view, this is a good first step.”
Alongside the current focus on trying to support hydroelectric power generation, Roerink said, “I think we need an option that’s just a bypass option with no power plant at the end.”
Roerink said he expects there to be a lot of discussion about issues such as evaporation from the reservoir and the high cost of remodeling the dam.
“Is it all worth it? Will those electrons be worth taxpayers’ money?” said Roerink. “How long will it be before this turns out to be a futile exercise?”
John Wisdom, an activist who has campaigned for the dam’s removal, said he was pleased to hear federal officials openly discuss these options for the first time.
“I’m glad we’re having this conversation. It’s long overdue,” says Wisdom, co-founder of the group Living Rivers.
Wisdom said he also thinks the agency’s alternatives are not broad enough, leaving questions about the lifespan of the dam unanswered.
“I think it’s imperative that we know exactly the lifespan of this dam,” Wisdom said. “There is still so much to talk about”
Wisdom said a key concern should be the accumulation of sediment at the bottom of the reservoir, which has lost nearly 6.8% of its water-holding capacity, according to a recent federal survey.
Another problem with the agency’s current alternatives, he said, is that they won’t solve problems with intake or bypass pipes that suck in air when the water level is low, “just like any bathtub,” potentially causing cavitation leading to holes and cracks in metal would result in damage to infrastructure.
Wisdom said he was also concerned about potential threats to endangered fish in the Grand Canyon.
All in all, the conversions on the dam that the federal government is considering are “too much investment for very little return”, according to Wisdom. “And it’s going to be a long, long time.”
Wisdom said he supports the opportunity to invest in solar and wind energy. Rather than spend up to $3 billion trying to squeeze a shrinking amount of energy out of the dam, he said, “You can build a lot of solar panels and turbines,” including near the Navajo Nation that needs electricity.
Wisdom said he thinks the situation shows that the Glen Canyon Dam is not needed.
“Take the dam out,” he said, “because it’s not the right dam for climate change.”
https://www.latimes.com/environment/story/2023-02-18/federal-officials-consider-overhauling-glen-canyon-dam Federal officials consider overhauling Glen Canyon Dam