Can the Glen Canyon Dam be modified to continue producing power if drought continues?

A $2 million study by the Bureau of Reclamation hopes to find out.

(Rick Egan | The Salt Lake Tribune) The Glen Canyon Dam on the Colorado River in northern Arizona, on Tuesday, Aug. 3, 2021.

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As the Colorado River basin continues to suffer from the worst twenty-year period of drought in at least 1,200 years, the Bureau of Reclamation is studying potential modifications to Glen Canyon Dam that could allow continued hydropower production despite rapidly dropping reservoir levels.

Lake Powell is currently filled to just over a quarter of its potential capacity, causing Glen Canyon Dam to be dangerously close to losing its ability to generate electricity. The intakes for hydropower production can only be used if the reservoir is filled to at least 3,490 feet above sea level, just 38 feet below the current elevation of Lake Powell.

This month’s projections from the Bureau of Reclamation show that it is possible Lake Powell — the nation’s second-largest reservoir after Lake Mead — could sink to an elevation that would stop hydropower production before the end of the year, though most projections suggest that is unlikely.

The bureau has set aside $2 million in drought funding to study potential modifications to the dam, which could include adding turbines and generators to the bypass tubes that can drain water from the reservoir, even if it drops 100 feet below the existing hydropower intakes.

The study will also look at modifying the intakes to draw water from a deeper level in Lake Powell.

Nick Williams, the agency’s Upper Colorado Basin power office manager, said in a written statement that the study is still in its early stages and is set to begin in mid-April or early May. It will likely take several months to complete.

“We’re entering studies to look at what we can do to ensure we can continue to generate power at the dam and still meet our water obligations under the Colorado River Compact,” Williams said, referring to the agreement between the seven Colorado River basin states of Utah, Wyoming, Colorado, New Mexico, Arizona, Nevada and California that determines how much water needs to be released from Lake Powell each year.

“In addition to seeking the best-available science, Reclamation is actively exploring the feasibility of modifications to Glen Canyon Dam to be able to produce power below the current minimum power pool elevation (3,490 feet), and perhaps as close as we can get to dead pool elevation (3,370 feet),” Williams said. “As we’re still in the planning process, we will continue to work with the Basin States, stakeholders, and partners on the best possible outcomes to protect facilities and water level.”

With a maximum capacity of 1,320 megawatts, the Glen Canyon Dam produces five billion kilowatt-hours of hydroelectric power annually, enough to power roughly 450,000 homes. Hydropower generated at the dam is sold to 5 million customers in Utah, Wyoming, Colorado, New Mexico, Arizona, Nevada, and Nebraska through the Western Area Power Administration.

A Bureau of Reclamation official discussed the study at a public Glen Canyon Dam management meeting earlier this month.

Jack Schmidt, director of the Center for Colorado River Studies at Utah State University, said the study’s announcement is indicative of the new reality in the Colorado River basin.

“To me that says it all,” Schmidt said. “If Reclamation is going to spend two million bucks to figure out how to produce power from a lower level … that’s enormous.”

Under the Colorado River Compact of 1922, the upper basin states must release a set amount of water into the Grand Canyon below Lake Powell every year. If the dam isn’t modified, the releases would still occur, but no power would be generated.

The Bureau of Reclamations’ latest forecasts show that, in the most probable scenario, Lake Powell will have more water in it two years from now than it does today.

But Schmidt and four other researchers released a white paper on Friday that shows the bureau’s forecasts have sometimes projected higher flows into Lake Powell over the last decade than actually occurred.

The bureau’s estimates for runoff in the Colorado River are based on the last 30 years of record: ten relatively wet years in the 1990s and the following 20 drier years, which many scientists have called a climate change-related “megadrought.”

Basing projections on 30 years of data in forecasts can skew results to be overly optimistic, the paper showed. But that doesn’t mean there is a conspiracy to produce inaccurate results, according to Schmidt.

“Reclamation is [made up of] hardworking and well-intentioned people who care,” he said, adding that it has generally been accepted that including more data in forecasts is better.

“But the problem is if the [additional] data is from a different climatological regime,” Schmidt said, “then actually more data is worse rather than better.”

Zak Podmore is a Report for America corps member for The Salt Lake Tribune. Your donation to match our RFA grant helps keep him writing stories like this one; please consider making a tax-deductible gift of any amount today by clicking here.