In 2000, the American West entered a megadrought that became its driest stretch in roughly 1,200 years. Years later, it left major lakes and reservoirs majorly depleted, with some losing enough water to expose miles of lakebed

Some of North America’s best-known lakes are becoming strikingly smaller. Across the American West, reservoirs and terminal lakes are holding far less water than they once did. The decline has been driven by a combination of drought, warming temperatures and heavy demands on limited water supplies. For some lakes, the change is now impossible to miss.

In 2000, the American West entered a megadrought that became its driest stretch in roughly 1,200 years. Years of heavy water diversion added to the strain, leaving some of North America’s major lakes and reservoirs dramatically depleted. In several places, falling water levels have exposed miles of once-submerged lakebed, as per a report by World Atlas.

Which lakes have lost the most water?

Lake Powell: How far has the reservoir fallen?

Lake Powell was created when Glen Canyon Dam closed its diversion tunnels in March 1963, allowing the Colorado River to back up behind the dam. It eventually became the second-largest reservoir in the United States.

At full capacity, Lake Powell stretches about 186 miles and can hold roughly 25 to 26 million acre-feet of water. For decades, its shoreline and more than 90 side canyons attracted summer visitors to the Glen Canyon National Recreation Area.

But the reservoir has been under growing pressure since 2000. The megadrought reduced the Rocky Mountain snowmelt that feeds the Colorado River, while the seven basin states continued drawing their allotted shares.

Lake Powell reached a modern low of 3,519.92 feet in April 2023, when it was near a quarter of its capacity. Federal managers have released water from upstream reservoirs such as Flaming Gorge, while states in the Colorado River basin have negotiated reductions in water use.

Its recovery remains closely tied to the snowpack in the Rocky Mountains, which supplies most of its inflow.

Why is Lake Mead still struggling?

Lake Mead was created by Hoover Dam, completed in 1936, and became the largest reservoir in the country by capacity. It was designed to hold nearly 29 million acre-feet and stretches about 112 miles upstream.

Located roughly 25 miles east of Las Vegas, Lake Mead supplies water to Las Vegas as well as Phoenix, Los Angeles and San Diego. For much of the 20th century, it served as a major storage buffer for the Lower Colorado River basin.

Since 2000, the same prolonged drought affecting Lake Powell has pulled Lake Mead downward. Its surface has fallen more than 150 feet from its historic high, exposing the pale mineral "bathtub ring" along the shoreline. The reservoir reached record lows in 2022.

Population growth has added another layer of pressure. Areas once served by the reservoir have grown into large metropolitan regions with millions of residents.

Water users have responded through conservation efforts, including reduced irrigation, expanded recycling and greater use of drought-tolerant landscaping.

What happened to the Great Salt Lake?

The Great Salt Lake is the largest saltwater lake in the Western Hemisphere. It is the remaining portion of the much larger Ice Age Lake Bonneville, which covered much of the region before the climate warmed roughly 14,000 years ago.

Today, the terminal lake receives water from the Bear, Weber and Jordan rivers but has no outlet. Water leaves mainly through evaporation, concentrating salts in the remaining lake.

Reduced streamflow and rising temperatures pushed the Great Salt Lake to a record-low elevation in 2022. At the Saltair gauge, the surface reached 4,190.1 feet, the lowest level recorded since measurements began in 1847.

The lake has lost roughly half its surface area compared with its 20th-century average and about two-thirds of its volume from its peak in the 1980s.

That retreat has exposed lakebed capable of producing toxic, arsenic-laced dust. Utah has responded by acquiring water rights, restoring wetlands and encouraging residents to reduce lawn irrigation.

Wet winters in 2023 and 2024 raised the lake, but it remains well below a healthy level.

Why has the Salton Sea shrunk so dramatically?

The Salton Sea has an unusual beginning. In 1905, Colorado River floodwaters broke through an irrigation canal under construction in California's Imperial Valley and flowed into the Salton Sink for about two years.

Farm drainage later helped maintain the lake. By the 1950s, the Salton Sea had become a resort destination known for water sports, fishing and boating. It was even promoted as "California's Riviera."

The situation later changed sharply. Evaporation increased the concentration of salt, agricultural runoff brought fertilizers and pesticides into the water, and fish die-offs became common. A sulfurous smell also drove tourism away.

As farms became more efficient and water transfers redirected supplies toward coastal cities, inflows dropped. The lake now covers roughly 340 square miles, with its volume down by millions of acre-feet since the early 2000s.

California has chosen not to return the Salton Sea to its former size. Instead, efforts are focused on dust suppression and habitat projects around the exposed shoreline.

How much water has Walker Lake lost?

Walker Lake has experienced one of the most dramatic declines of all. The terminal lake in west-central Nevada has lost roughly 90 percent of its volume.

The lake is a remnant of the much larger Ice Age Lake Lahontan. It receives water from the Walker River and Sierra Nevada snowmelt, but like the Great Salt Lake, it has no outlet other than evaporation.

Its decline began around 1882, when farmers and ranchers upstream began diverting the Walker River for irrigation.

Over the following century, the lake’s surface elevation dropped by about 150 feet. Storage fell from roughly 9 million acre-feet to less than 2 million.

As the water disappeared, dissolved solids became increasingly concentrated, threatening Lahontan cutthroat trout, which is listed as threatened under the Endangered Species Act.

The Walker Basin Restoration Program has acquired water rights from willing sellers to return flows to the lake. Heavy snow years have provided temporary relief, but the long-term trend remains downward.

Can these lakes recover?

The five water bodies are different, but their problems overlap.

Lake Powell and Lake Mead are Colorado River reservoirs facing pressure from reduced river flows and demand across a growing region. The Great Salt Lake and Walker Lake are terminal lakes where upstream diversions leave less water to offset evaporation.

The Salton Sea is different again. Created by an accident involving the Colorado River, it is now being managed toward a smaller and more stable footprint rather than restored to its former size.

Across all five, reduced inflow and warming temperatures have played major roles. The route toward stabilization involves water rights, conservation and the snowpack that supplies much of the region’s water.

For these lakes and reservoirs, the challenge is ultimately how closely water use can be matched to what a warmer climate continues to deliver.

FAQs

Which lake lost the most water?
Walker Lake has lost roughly 90 percent of its volume.

Why are Western lakes shrinking?
Reduced inflows, warming temperatures and water diversions are major factors.