On Tuesday, a massive reservoir known as a boating mecca fell below a critical level, raising new concerns about a source of power that millions of people in the United States’ West rely on for electricity.

Lake Powell’s drop to below 3,525 feet (1,075 meters) is the lake’s lowest level since it filled after the federal government dammed the Colorado River at Glen Canyon more than a half century ago — a record that underscores the devastating effects of climate change and megadrought.

It occurs as a result of hotter temperatures and less precipitation, which result in less water flowing through the overburdened Colorado River. Though water scarcity is not new in the region, hydropower concerns at Arizona’s Glen Canyon Dam indicate that a future that western states thought was years away is approaching — and fast.

Water levels are expected to rise in the coming months as snow melts in the Rockies, according to federal officials. However, they warn that more work may be required to ensure Glen Canyon Dam can continue to produce hydropower in the future.

“Spring runoff will solve the deficit in the short term,” said Wayne Pullan, regional director for the United States Bureau of Reclamation, which manages water and power in a dozen states. “However, our work isn’t finished.”

Despite the fact that Lake Powell and its downstream counterpart, Lake Mead, are both dropping faster than expected, much of the region’s attention has been on how to deal with water scarcity in Arizona, Nevada, and California, rather than electricity supply.

If Lake Powell continues to fall, it may soon reach “deadpool,” the point at which water will likely fail to flow through the dam and onto Lake Mead. Arizona, Nevada, California, and Mexico have already implemented a mix of mandatory and voluntary cuts tied to Lake Mead levels.

Glen Canyon Dam generates power for approximately 5 million customers in seven states: Arizona, Colorado, Nebraska, Nevada, New Mexico, Utah, and Wyoming. It is provided by the government at a lower cost than energy sold on the wholesale market, which can be wind, solar, coal, or natural gas.

Less water flowing through Glen Canyon Dam can therefore increase total energy costs for the cities, rural electric cooperatives, and tribes that rely on its hydropower. Customers bear the brunt of the consequences.

The Navajo Tribal Utility Authority, one of 50 tribal suppliers who rely on the dam for hydropower, is concerned about the situation. This year, it intends to spend $4.5 million on alternative energy sources.

Last summer, officials from the Bureau of Reclamation took an unprecedented step, diverting water from reservoirs in Wyoming, New Mexico, Utah, and Colorado in what they called “emergency releases” to replenish Lake Powell. The agency also held back water scheduled to be released through the dam in January to prevent it from falling even lower.

Anxiety extends beyond hydropower. Falling lake levels hampered tourism and boating last summer. The Glen Canyon National Recreation Area is taking advantage of Lake Powell’s low levels to build new boat ramps. Most are now closed or come with a disclaimer that you launch at your own risk.

In Page, Arizona, which benefits from Lake Powell recreation, officials launched a campaign this month to emphasize that lower levels aren’t necessarily bad for visitors, pointing out that receding shorelines have revealed sunken boats, canyons, and other geological wonders.

The record low comes on the heels of a difficult year for hydropower. Drought in the West caused a drop in hydropower generation last year, making it difficult for officials to meet demand as the United States worked to expand renewable energy. More than one-third of the nation’s utility-scale renewable energy comes from hydropower.

Many variables, including precipitation and heat, will determine the extent to which Lake Powell recovers in the coming months, according to Nick Williams, the bureau’s Upper Colorado Basin power manager.

Regardless, hydrology modeling indicates that there is a one-in-four chance that it will not be able to produce power by 2024.