Lake Mead, the largest reservoir on the Colorado River, is expected to fall below an elevation of 1,035 feet above sea level within the next 12 months, possibly as early as late August, according to reporting by Circle of Blue published by Inside Climate News on June 12, 2026. At that level, generating capacity at Hoover Dam would be cut by 70%, because 12 of the dam's 17 turbines are not designed to operate in such low-water conditions.
"We're going to go to 1,035," Tom Buschatzke, director of the Arizona Department of Water Resources, said at a meeting in mid-May. "There's no question that's going to happen."
Mead stood at about 1,050 feet in early June and had been dropping roughly one foot every five days, according to the report. The lower basin states of Arizona, California and Nevada have proposed a conservation plan that could keep the reservoir above 1,035 feet until next spring, so the timing remains uncertain.
Why Mead is falling
The decline follows record-low winter runoff into reservoirs that were already depleted after more than two decades of drought in the Colorado River basin. In April, the Bureau of Reclamation decided to reduce releases from Lake Powell, upstream behind Glen Canyon Dam, by 20% this year. The decision was made to protect Glen Canyon's water-delivery infrastructure and keep its hydropower running, because Powell would otherwise have fallen below its own minimum power level by the end of summer. Holding back water in Powell, however, accelerates the decline of Mead downstream.
New turbines
Reclamation announced on May 21 that it will spend $52 million on three new wide-head turbines able to generate power down to an elevation of 950 feet. Once those are installed alongside the five existing wide-head units, the capacity cut when Mead falls below 1,035 feet would be 58% rather than 70%, according to the report. Reclamation did not provide an installation timeline before publication.
Effects on power customers
Hoover's electricity is sold under contracts to utilities and public power agencies in Arizona, California and Nevada. Hoover's output is already between 40% and 50% lower than in 2000, when Mead was full, according to the report.
Lincoln County Power District in eastern Nevada, which serves about 5,000 people, gets about 70% of its electricity from Hoover. Its general manager, Dane Bradfield, said the district has secured enough power through 2026 by hedging with market contracts and adding solar, and is now looking ahead to 2027.
The cost of Hoover power is likely to rise. The rate covers fixed costs including operations and maintenance, visitor center operations, ecosystem programs and repayment of construction costs for the Central Arizona Project canal. With less power to sell, the cost per unit increases. Jordy Fuentes, executive director of the Arizona Power Authority, said the rate could triple, though the timing is uncertain.
Effects on the grid
Hydropower is valuable to the grid not only for its energy but for its ability to ramp up and down quickly. That flexibility helps balance demand in the early evening, when solar output drops and household demand rises. Nathalie Voisin of Pacific Northwest National Laboratory said the loss of Hoover capacity does not mean the grid will go dark, but that other resources will be used to provide those services at higher cost.
The Western Electricity Coordinating Council, which assesses reliability in the western interconnection, is working with researchers at Pacific Northwest National Laboratory and the National Laboratory of the Rockies to model how the grid would respond to a large loss of Hoover capacity under different weather and demand scenarios, according to WECC's Katie Rogers. Questions include whether growing battery storage can replace Hoover's ramping capability and whether a spring heatwave would be more problematic than a summer one.
Climate and the Colorado River
The Colorado River supplies water to about 40 million people and irrigates large areas of farmland in seven US states and Mexico. Its flows have declined over the past two decades as temperatures have risen, increasing evaporation and reducing the share of snowfall that reaches rivers. Scientists have attributed a significant part of the decline to warming. Negotiations over new operating rules for the river, which expire after 2026, have been under way among the seven basin states and the federal government.
Fuentes said that, absent changes in hydrology, hydropower in both the upper and lower basins is "absolutely in trouble and directly related to drought."
Western power markets
Lower hydropower output affects the wider western power market. In dry years, utilities across the West buy more power from gas plants and from markets, raising costs. Western hydro generation also includes the large Pacific Northwest system on the Columbia River, whose output varies with snowpack. Drought in multiple basins at once tightens supply across the interconnection, particularly during summer heatwaves when demand is highest.
The Southwest has added large amounts of solar and battery storage in recent years, which helps offset some of the lost hydropower. Batteries can provide fast ramping, though for shorter durations than reservoirs. Gas plants remain the main source of firm capacity during long heatwaves.
Data centers in the desert
The Phoenix and Las Vegas areas have become significant data center markets, adding to electricity demand in the same region where Hoover's output is falling. Data center operators in Arizona have faced scrutiny over water use, and many have adopted cooling designs that use less water. Utilities including Arizona Public Service and Salt River Project are adding generation and storage to meet growth from data centers and manufacturing.
Glen Canyon and the upper basin
The upper basin faces its own hydropower risk. Glen Canyon Dam is the second-largest generator on the river, and its power is marketed by the Western Area Power Administration to utilities across several states. Reclamation's April decision to cut Powell releases was intended to keep Glen Canyon above its minimum power pool, but it leaves less margin downstream.
What to watch
Key items include the timing of Mead's fall below 1,035 feet, the installation schedule for the new turbines, the outcome of the basin states' conservation plan and negotiations over post-2026 river operations, and the summer monsoon, which could slow the decline. WECC's modelling results will indicate how much the loss of Hoover's flexibility affects western grid reliability.