Lake Mead, the largest reservoir in the United States, has fallen to its lowest water level since it was first filled roughly 90 years ago, intensifying alarm over the worsening crisis gripping the Colorado River system. Water levels at the reservoir — which straddles the Arizona-Nevada border just outside Las Vegas and is held back by the iconic Hoover Dam — reached 1,040.4 feet (317.1 metres) above sea level, dipping just below the previous record set on 28 July 2022, according to data from the US Bureau of Reclamation. Federal officials warn the level is expected to keep falling through much of the remainder of the year.
The Colorado River is a vital artery of the American West, supplying water to roughly 40 million people across seven US states, tribal nations and Mexico, and irrigating millions of acres of farmland. The river's two primary reservoirs — Lake Mead and Lake Powell, which sits upstream in northern Arizona and southern Utah — are now both at their lowest levels in nearly seven decades. This past winter delivered the worst snowpack on record for the Colorado River basin, compounding the pressure on a system already strained by decades of overuse, prolonged drought and rising temperatures. Snowmelt from the Rocky Mountains, where the river originates, is a critical source of water replenishment, and its near-absence this season has had cascading consequences for farmers, cities, wildlife and hydropower producers alike.
"It's extremely significant and extremely concerning," said JB Hamby, chair of the Colorado River Board of California and a board member of the Imperial Irrigation District, the largest single user of the river's water. "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." Hamby stressed the urgent need for all water-dependent states to reduce their consumption.
The crisis has already produced dramatic consequences. During a severe drought in 2022, receding waters at Lake Mead exposed human remains and forced Las Vegas water managers to pump from deeper within the reservoir. At Lake Powell, water levels have dropped so sharply that boat ramps have had to be relocated, closed or entirely rebuilt. Beyond these two reservoirs, nine of the 54 western reservoirs tracked by the Bureau of Reclamation have recently recorded their lowest levels in three decades.
On the governance front, the seven states that rely on the Colorado River — California, Colorado, Arizona, Nevada, New Mexico, Wyoming and Utah — have failed to reach a long-term agreement on sharing its dwindling waters. In response, federal officials put forward a short-term proposal requiring the Lower Basin states of Arizona, California and Nevada to accept reduced allocations, with the possibility of deeper cuts during drier periods. A formal record of decision is expected in the coming weeks, though experts caution it may not be sufficient to resolve the river's long-term structural imbalance between supply and demand. Adding further complexity, federal officials have decided to halt the release of cool water from Glen Canyon Dam — a measure normally used to protect the humpback chub, a threatened native fish — in order to safeguard the system's hydropower capacity.