Glen Canyon Dam, which supplies electricity to 28 Colorado utilities, has been a stabilizing force in the West’s power supply. This year could be one of the lowest power production years ever.
Power generation at Glen Canyon fell by 17% on average from 2000 to 2023, compared with pre-drought years from 1988 to 1999, according to the Bureau of Reclamation, which manages the dam. The decline has made electric utilities more dependent on the volatile energy market, forced some to increasingly rely on fossil fuel energy sources, and raised rates by about 7%.
“Here in 2024, we’re expecting levels that are going to be among some of the lowest generation years that we’ve ever seen at Glen Canyon,” said Nick Williams with the Bureau of Reclamation. “Other than ‘22, you have to go back to the 1960s when the reservoir was still filling to find years as low as what we’ll see.”
Hydropower generation in 2024 is expected to be the second lowest year for generation with an estimated total of about 2.98 million megawatt-hours.
This Fresh Water News story is a collaboration between The Colorado Sun and Water Education Colorado. It also appears at wateredco.org/fresh-water-news.
Near the Utah-Arizona border, Glen Canyon Dam catches Colorado River water that flows from Upper Basin states, including Colorado, New Mexico, Wyoming and Utah, in a massive reservoir called Lake Powell.
That water flows through turbines to generate hydroelectric power. Glen Canyon’s power is pooled with hydropower from other dams, including three in Colorado — Blue Mesa, Crystal and Morrow Point in Montrose and Gunnison counties — and delivered to Wyoming, Colorado, Arizona, New Mexico, Nevada, Texas and Utah.
In Colorado, Tri-State Generation and Transmission Association, Colorado Springs, Fort Morgan, Delta, the Southern Ute and Ute Mountain Ute tribes, the Platte River Power Authority, and many more get a portion of their electricity from Glen Canyon and its sister dams.
For decades, these federal dams have offered a cheap, renewable and consistent power source that can be ramped up or down quickly. That’s a helpful tool to keep up with ever-changing demand as people boost air conditioning, flip on lights and power up appliances at different times of the day.
The historic drought in the Colorado River Basin has raised new questions about that reliability in the future.
“The megadrought … has certainly brought Lake Powell to some of its lowest levels since it was initially constructed and filled,” said Williams, a power manager for Reclamation’s Upper Colorado Basin Region Power Office. “That’s impacted hydropower too.”
A power drop at Glen Canyon
Since 2000, the basin has experienced its driest 22-year period in a 1,200-year record, which gradually chipped away at the basin’s water storage in reservoirs. By 2022, the water levels in Lake Powell had dropped to historic lows, and power production was at its lowest since 1964, when production was just starting.
Fourteen of the lowest generation years at Glen Canyon Dam have occurred since 2000, according to Jerry Wilhite with the Western Area Power Administration, a federal agency that sells and distributes power produced at federal dams.
“A lot of people … would say it’s probably not drought, it’s aridification. This may be the new permanent,” said Wilhite, an environmental protection specialist. “We haven’t seen a period this long of this low water availability in the Colorado River Basin in a long time.”
The decline prompted a crisis response among basin officials: If the reservoir’s elevation falls below 3,490 feet above sea level, it can no longer release water for power production. At the time, forecasts showed water levels could actually fall below that elevation for the first time in the reservoir’s history.
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Glen Canyon makes up about 78% of the power produced by dams in the Colorado River Storage Project, which includes the dams in Gunnison and Montrose counties. If it can’t produce electricity, utilities would end up with less hydropower than expected.
With everyone shopping for replacement energy on the open market, prices would spike — if there is enough energy available to meet demand at any given moment, said Leslie James, executive director of the Colorado River Energy Distributors Association.
The association represents utilities across the West that buy federal hydropower from Glen Canyon and its sister dams in the Colorado River Storage Project.
Utilities have varied portfolios and would still be able to serve their customers, but they might have to rely on more expensive or nonrenewable energy sources.
“If we have less renewable energy in the form of hydropower … they have to go find those renewable energy credits somewhere else,” Wilhite said.
The reservoir’s water levels have rebounded to about 3,581 feet — similar to water levels in 1969 and 2018 — since reaching an all-time low of about 3,521 feet in February 2023. Power generation, however, is slow to follow.
Lower water levels mean reduced annual releases from the dam, based on interstate rules established in 2007. Dam operators have to work within those annual limits as they try to balance the fluctuating demand for electricity with environmental regulations and operating restraints.
Lower water levels also make power generation less efficient because there is less pressure bearing down on the turbines. In 2023, Glen Canyon generated about 3,300 gigawatt-hours of electricity. If the reservoir had been full, it could have generated 4,390 gigawatt-hours, or 32% more energy.
One generator at Glen Canyon has a capacity of 165 megawatts — if the reservoir is near its capacity of 3,700 feet.
“At our current elevation, we’re getting a little over 100 megawatts per unit,” Williams said.
How do Powell’s levels impact Coloradans?
Colorado electric utility companies are keeping an eye on Glen Canyon Dam and other federal dams to gauge impacts to their wallets and energy plans.
The federal agencies do not make a profit off their energy services. Federal rates serve to cover agency expenses. As the dams have produced less hydropower, the agencies have had to raise their rates. In 1987, a customer paid about $5.91 per kilowatt-month, adjusted to today’s dollars. Today, they pay about $6.31, a 6.7% increase.
It’s still one of the cheapest energy options available, said Sean Whelan, vice president of finance for Holy Cross Energy, which serves about 47,000 customers in and around the Aspen corridor.
“Anytime it’s not available, we’re having to source more costly power to replace that,” he said.
If there’s less federal hydropower than expected, utilities can pay agencies to replace it for them or they can find replacement power on the energy market by themselves.
Replacement power is often more expensive for utilities than the federal rate. On the open market, energy prices vary widely from $60 to $200 per megawatt-hour. During an energy crisis in 2000, they reached $1,000. The federal rate is closer to $30, said James of the energy distributors association.
Power from the energy market also comes from mixed sources, including solar and natural gas, but gas isn’t an option for cities like Aspen that aim to sustain their 100% renewable energy system.
That means there’s more competition for finite renewable resources as communities try to shift their energy supplies, said Justin Forman, Aspen’s director of utilities.
So far, Colorado utilities have been able to navigate the fluctuations in federal hydropower supplies, in part because of their varied energy portfolios. Holy Cross, the city of Aspen, Colorado Springs Utilities and CORE Electric Cooperative all receive less than 5% of their overall portfolio from the Western Area Power Administration and the federal dams.
But as the drought continues and water demands on the Colorado River are slow to adapt, some Colorado utilities are also preparing for a future where hydropower plays a smaller role in the Western energy supply, said Chris Hildred, power supply director with CORE Electric Co-op.
“Hydropower is probably not going to be a growing resource in the West,” Hildred said. “It’ll still be a piece of the puzzle, but as loads grow, it’ll continue to be a shrinking piece of the puzzle, even if rainfall and snowpack levels are able to support the current level of generation.”