Lake Powell sits less than 1% above the level where its dam can no longer make power

Glen Canyon Dam holds back the second-largest reservoir in the country, and by the end of September the water behind it stood about 28 feet above the elevation where its eight turbines stop turning. The U.S. Energy Information Administration put that cushion at less than 1% of the way to the floor. A summer of record-low output across the Southwest had already shown what a thinning margin costs in kilowatt-hours.

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The summer numbers are the visible damage. From April through August, hydropower output in the Southwest ran 19% below the same months of 2025 and 28% below the 10-year average, according to the federal agency’s Nov. 13 note on the region. Lake Powell’s end-of-September elevation of 3,518 feet is the figure that carries the most risk going into winter, because it sits so close to the point where the dam can no longer generate at all.

3,518 feet against a 3,490-foot floor

EIA’s Nov. 13 Today in Energy note reports that Lake Powell reached 3,518 feet at the end of September, less than 1% above minimum power pool. Bureau of Reclamation data reported by KSL puts that floor at 3,490 feet, the elevation below which the water is too low to turn the turbines, which makes the end-of-September margin roughly 28 feet. Glen Canyon Dam’s eight turbines generate enough electricity for nearly 500,000 households, so the cushion is measured against real load.

Powell had already set a record on Saturday, Aug. 15, sliding to 3,519.91 feet and edging under the 3,519.92 feet logged in April 2023. The end-of-September reading of 3,518 feet is roughly two feet below even that mark, so the lake kept falling after it made the record books. In mid-August, the Post Independent and KSL both described Powell as sitting just under 30 feet above the power floor, which means about two feet of that cushion vanished in six weeks.

Brad Udall, a senior water and climate research scientist at Colorado State University, called 3,490 feet a “scary threshold” in that KSL report and said Powell would reach it this year unless extraordinary measures were taken. Jack Schmidt, who directs the Center for Colorado River Studies at Utah State University, said the reservoir was in “uncharted territory.” The elevation EIA cites is an end-of-September reading, so Reclamation’s daily data, not the EIA note, would show where the lake stands now.

A summer of record-low output at Glen Canyon and Hoover

KJZZ in Phoenix, reporting on the EIA findings on Nov. 13, said Glen Canyon and Hoover dams both fell to record-low output this summer, and that the two plants account for up to 90% of hydropower on the Colorado River. The station added that generation this year is expected to be the lowest since at least 2016, with similar levels projected for next year. Because those two dams dominate the river’s power, a drought that drains two reservoirs shows up as a regional number.

The Colorado River’s reservoirs were at all-time lows in August, the Post Independent reported: Powell about 22% full and Lake Mead about 27% full at 1,040 feet on Friday, Aug. 14, below its 2022 record. Hydropower rises and falls with the height of water above the turbines, so the same lower elevation that raises the shutdown risk also trims every megawatt-hour produced in the meantime.

Reclamation’s emergency releases and the post-2026 rules

The Bureau of Reclamation announced emergency actions in April, including limiting Powell releases to the Lower Basin states and sending water downstream from Flaming Gorge Reservoir, the Post Independent said. The bureau also released a final environmental impact statement for post-2026 operations, to be managed in two-year increments through 2036. David Rosenberg of Utah State University said the framework sets protection elevations and a buffer volume meant to reduce the risk of losing hydropower. A Reclamation spokesperson said the agency and the Interior Department are committed to reducing the risk of Powell and Mead falling below critical elevations.

The 3,490-foot power line is the first of two thresholds. The lowest possible level, dead pool, sits below 3,370 feet, where water can no longer flow downstream from the dam at all. EIA publishes its generation forecasts in the monthly Short-Term Energy Outlook, the document that would carry any revised expectation for Southwest hydropower.

The politics around the rules are as unsettled as the hydrology. The Post Independent reported that Arizona Gov. Katie Hobbs rejected the federal operating options as unacceptable, while Colorado River District manager Andy Mueller argued that the framework leaves the basin managing one crisis after another. Glen Canyon Dam, built in the 1950s, sits at the center of that argument because every foot of Powell’s elevation decides how much power its turbines can still produce.

What the end-of-September reading cannot settle is the winter. The 28-foot cushion was measured before any new snowpack arrived, and Sarah Porter, who directs the Kyl Center for Water Policy at Arizona State University, said in August that record snowpack alone would not fully end the danger.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.