Lake Mead, the largest reservoir in the United States, has dropped to its lowest water level in history, triggering urgent warnings that severe water shortages and power outages could soon affect up to 40 million people across the Southwest.
The US Bureau of Reclamation warned that Hoover Dam on the Colorado River, along with the Glen Canyon Dam 300 miles away, are both just feet away from being forced to shut down their hydroelectric turbines as water levels drop.
Formed by Hoover Dam on the Colorado River between Nevada and Arizona, Lake Mead was once considered full when its water reached 1,220 feet above sea level. As of Tuesday, the water level had fallen to just under 1,040 feet.
A similar decline is occurring 300 miles away at Glen Canyon Dam, which supports Lake Powell, another major reservoir fed by the Colorado River. The US Bureau of Reclamation, which manages federal dams and reservoirs, warned that both facilities face imminent turbine shutdowns.
Hydroelectric power generated at the two dams currently supplies electricity to nearly two million people across eight states: Arizona, California, Colorado, New Mexico, Nevada, Nebraska, Wyoming, and Utah.
Beyond electricity, between 30 million and 40 million people across seven Southwestern states rely on the Colorado River for drinking water, household plumbing, and agricultural irrigation. Major cities including Las Vegas, Phoenix, and Los Angeles, as well as numerous smaller communities, draw a large share of their water from these reservoirs. The drop in water levels at Lake Mead and Lake Powell has become so pronounced that the white bathtub ring marking the former water line can be seen from commercial passenger planes flying thousands of feet above Nevada and Arizona.
Hydroelectric power production risks
At Lake Mead, power generation has reached an alarming point. Water levels sit just five feet from the threshold where older turbines at the hydroelectric facility will be forced to shut down to prevent equipment damage.
Only newer wide-head turbines can continue operating at lower water levels, but their operation will result in a sharp drop in overall power output. Hoover Dam serves over one million people across Arizona, California, and Nevada, generating roughly four billion kilowatt-hours of hydroelectric power each year. If drought conditions push the reservoir level below 950 feet, the entire facility will have to shut down.
Upstream, Lake Powell is just 30 feet away from dropping to the point where its hydroelectric turbines must shut down, threatening power supplies for an additional 300,000 people across the Great Plains and the Southwest. If water levels in either Lake Powell or Lake Mead fall too low to produce power, utility companies that depend on cheap hydropower will need to scramble for replacement electricity from other sources, typically more expensive natural gas.
Switching to alternative power generation is expected to raise electricity bills for regional customers while placing additional strain on the electrical grid, increasing the risk of blackouts during extreme weather. Water will still be able to flow downstream through smaller outlet pipes, but with reduced capacity and control, making it harder to manage water supplies for municipal households and farm crops.
Drought causes and long term projections
The water crisis is driven by severe drought conditions across the region, particularly near the source of the Colorado River in the Rocky Mountains. Unusually low snowpack totals have resulted in less melting snow entering the river to fill the reservoirs.
JB Hamby, chairman of the Colorado River Board of California, highlighted the scale of the threat in comments to the Associated Press: "It’s extremely significant and extremely concerning. You have three-quarters of the population of the Colorado River Basin, some 30 million people, who are directly impacted by risks to Lake Mead."
A report published by the Bureau of Reclamation in July projected that Lake Mead could drop by an additional 33 feet over the next two years. The reservoir currently operates at less than 27 percent of its total capacity.
Local resident John Belton described the situation online: "There's only two things that can save Mead and Powell right now: 150 percent Colorado Rockies snow pack for five consecutive years, or God himself."
Conditions are expected to worsen this week as a massive heat dome moves over the western half of the United States. AccuWeather forecasted that high heat and humidity will combine to push feels-like temperatures near or above 100 degrees Fahrenheit in states stretching from California to Arkansas. Higher temperatures accelerate evaporation and reduce water runoff, preventing snowpack from the Rockies from reaching the Colorado River.
Proposed water cuts and future operations
Last month, the Bureau of Reclamation released a proposed ten-year plan for operating Lake Powell and Lake Mead after existing guidelines expire at the end of 2026.
With both reservoirs at record lows, the federal proposal allows for mandatory water cuts, referred to as shortages, across Arizona, California, and Nevada. The planned reductions could cut water deliveries to those states by up to 40 percent of their current allocations from the reservoirs.
Addressing the proposed reductions, Hamby noted: "The proposal responds to a fundamental reality: the Colorado River no longer reliably produces enough water to support all the uses and expectations built around it."
