Home Water flow Hydropower concerns grow as Colorado River reservoirs continue to decline

Hydropower concerns grow as Colorado River reservoirs continue to decline

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Bureau of Reclamation’s Glen Canyon Dam manager Bob Martin stands on a ledge overlooking the Colorado River as he leaves Lake Powell. Credit: Luke Runyon / KUNC

state of science iconThis article is part of The State of Science, a series of scientific articles broadcast by public radio stations across the United States. This story was reported by Luke Runyon on KUNC.


Water levels behind the largest dams on the Colorado River are fast approaching or have already reached record levels. The historic 21-year mega-drought that is choking water supplies to some Western states will likely start showing up in energy bills as these dams cannot produce as much electricity.

The problem is most acute in the largest reservoir in the upper Colorado River basin: Lake Powell. At the base of the Glen Canyon Dam in northern Arizona, the Colorado River flows cold and clear. On the canyon walls, moss grows where water from behind the dam slowly seeps through the red sandstone. The air hums with electricity.

“If money had a sound, it would be this one,” Bob Martin said of the electric hum. He is the dam director for the US Bureau of Reclamation.

“You can hear the electricity,” he said. “It’s about keeping the lights on in businesses, the air conditioning in your home, powering hospitals, you name it. It really is the backbone of our company now.

a landscape photo of a gap between a canyon under which water flows.  a bridge and power lines span the ditch
The Glen Canyon Dam Power Plant transmission lines run from the base of the dam to the top of the canyon. Credit: Luke Runyon / KUNC

Above our helmets, thick metal transmission lines connect its powerhouse to the towers at the top of the canyon. When heat waves scorch the west, as they have this year, Martin says the dam can release more water to meet growing energy demands in places like Colorado Springs, Mesa, Arizona, St. George. , Utah and the Navajo Nation. Many rural power co-ops in the Colorado River Basin also rely on Glen Canyon and hydropower generated by smaller dams in Utah, Colorado, and New Mexico.

“When the sun goes down and it’s still hot and the wind isn’t blowing and you still have demand on the grid, people who run their air conditioning, this energy has to come from somewhere,” he said. said Martin. “This is the advantage of hydroelectricity, is that we can turn on the power in a few minutes to put it on the grid.”

Lake Powell is the second largest reservoir in the country. Later in July, it is expected to reach its lowest point since it was first filled in the 1960s, and is expected to drop below its previous low in 2005. Reservoir level is currently 3,557 feet above the level of. the sea. It is expected to drop to 3,515 feet by next spring. At an altitude of 3,490 feet, hydroelectricity production at the dam is no longer possible. Warming temperatures due to climate change and the West’s inability to conserve are to blame.

Inside the dam, water circulates through generators to generate electricity for 5 million people in seven western states: Nevada, Arizona, New Mexico, Utah, Wyoming, Colorado, and Nebraska. As the lake shrinks, so does its power generation, as there is less water pressure to drive the turbines. The pressure that builds up behind a dam and makes generators more efficient is called hydraulic head.

an interior of a large industrial building, with a large cylindrical machine in the foreground
Generators generate hydroelectricity inside the Glen Canyon Dam in northern Arizona. Credit: Luke Runyon / KUNC

With a declaration of shortage to come the federal government and restrictions on water deliveries set out in the 2007 Interim River Guidelines, the Glen Canyon Dam will pass less water in 2022, and will do so with less hydraulic head, meaning that its overall hydroelectric production is expected to decline further.

Hydropower generation at Glen Canyon has fallen by approximately 16% and its capacity has declined by approximately 20% since 2000.

Supplies to Powell from the Colorado and San Juan rivers this year are among the three lowest on record, at 24% of the long-term average. Downstream demands and long-standing agreements between basin states will push Powell to an all-time low, with no relief in sight. Declines similar to the Hoover Dam are also occurring.

“Even with efficiency improvements, the impacts on hydropower production are expected to continue,” hydrologists from the Bureau of Reclamation wrote in a report from March 2021. “Current projections for hydropower production at the Hoover Dam indicate that there is a relatively high probability of a 0.5% to 2.5% reduction in hydropower production from year to year over the years. Next 5 years. “

“It’s not sustainable to keep releasing that volume of water when you don’t have a lot of it coming in,” Martin said.


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Falling water levels have prompted those who market and distribute Colorado River Basin hydropower to their customers to figure out how to close the energy gap.

“It’s a tough conversation in the sense that all we have to say is bad news,” said Clayton Palmer, of the Western Area Power Administration, or WAPA. The agency distributes and markets electricity from the Glen Canyon Dam.

With the lake declining, Palmer said this year his agency will need to purchase millions of dollars in additional electricity on the open market to fulfill its contracts.

“Conversations with our customers have centered on how much less you should deliver or how much more should you raise your prices? Palmer said.

Lake Powell nears record low as the Colorado River Basin warms due to climate change. Credit: Luke Runyon / KUNC

WAPA has already started the process of increasing its rates by 14% for at least the next two years. What makes planning even more difficult, Palmer said, is that no one knows how badly things could turn out if the hot, dry conditions continue.

“Is it a series of drier years, which will be followed by a series of wetter years?” ” he said. “Or has there been a systematic change in climate and hydrology in the Colorado River Basin such that we should expect these conditions to be the new normal in the case of hydropower?” “

Even with the historic lows of 2021, the Colorado River dams still produce hydroelectricity. What is uncertain is what another dry year like this could do to fuel production in the watershed.

“I think this has been described as a slow train wreck,” said Eric Kuhn, the former general manager of the Colorado River District. “Because it took us 22 years to get to where we are today. “

Kuhn says it takes a series of consecutive dry years to jeopardize the river’s power generation. Lake Powell has now seen two in a row. One more could trigger a total loss of hydropower at the reservoir.

“I would say there’s a 40-50% chance that in the winter of 2023 we could see Lake Powell levels drop to minimum power or below,” Kuhn said.

None of this should come as a surprise, said Eric Balken of the Glen Canyon Institute, an environmental group based in Utah.

“I think for a lot of people the writing is on the wall,” he said.

Balken’s group advocates for voluntarily lowering Lake Powell, letting its water flow downstream to fill Lake Mead. The Colorado River system should now be managed for one giant reservoir, not two, Balken said. Environmental groups have demanded drainage of the lake for decades; they see in its dam a symbol of the excess water of the West. Without the reservoir, Balken’s group wants to see Glen Canyon restored.

And even if water managers don’t actively choose to abandon Lake Powell, climate change could end up doing it for them, he said.

“The Lake Powell that we knew in the ’80s and’ 90s is unlikely to come back,” Balken said. “And when it comes to climate data, you don’t have to be a mathematician to see the trend line.”

Climatologists say temperatures are likely to continue to rise, straining not only the region’s water supply, but its energy network as well.


This story is part of the continuing coverage of the Colorado River produced by KUNC Colorado and supported by the Walton Family Foundation.

Meet the writer

Luc Runyon

About Luke Runyon

Luke Runyon is the Water Reporter at KUNC in Greeley, Colorado.

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