The U.S.’ largest reservoir is drying up. Here’s what NASA images reveal

• Recent images revealed by NASA show that Lake Mead keeps dropping.
• Water levels of the lake are at their lowest since April 1937.
• Lake Mead is a source for millions of people, including citizens from Mexico.

The largest reservoir in the United States, Lake Mead supplies water to millions in seven states, tribal lands, and northern Mexico. However, recent images posted by NASA reveal that the lake is on the verge of a complete dry-up following a 22-year downward trend.

Currently, water levels stand at their lowest since April 1937, and as of July 18, 2022, the lake was filled to just 27 percent of capacity. The last time the lake was close to full capacity was in the summers of 1983 and 1999. At full capacity, Mead would reach an elevation of 1,220 feet (372 meters) near the Hoover Dam, and include 9.3 trillion gallons (36 trillion liters) of water, according to the data from the U.S. Bureau of Reclamation (USBR).

Unfortunately, things don't seem to be getting any better.

According to NASA, 74 percent of nine Western states suffer from different levels of drought; in particular, California, Nevada, Utah, and Oregon face extreme levels. In the meantime, only 17 percent of Colorado doesn't seem to be in drought.

What's more, the water elevation level at the Hoover Dam was 1041.30 feet (317.4 meters) above sea level on July 18, 2022. To compare, it was at around 1199.97 feet (341 meters) in July 2000, according to USBR. Lake levels of the dam should be above 1000 feet so that hydropower turbines can operate at normal levels.

Lake Mead sources around 10 percent of its water from local precipitation and groundwater in a year, while the remaining 90 percent comes from snowmelt in the Rocky Mountains that reaches the Colorado River watershed through Lake Powell, Glen Canyon, and the Grand Canyon. USBR and different agencies tap into the Colorado River basin to source water and power for nearly 40 million people; the basin also provides 4 to 5 million acres of farmland in the Southwest. Thanks to laws such as the 1922 Colorado River Compact, not only U.S. citizens but also people from Mexico benefit from this water source.

Lake Powell, 385 miles (620 km) from Lake Mead, is also filled to just 27 percent capacity, while the entire Colorado River system is at a 35 percent level.

As expected, water sources are currently away from reaching their full potential. Hence the state water allocations will be renegotiated in 2023, and they could be cut in 2022, USBR announced in 2021. Over the course of the next 18 months, the states that source water from the Colorado River basin are to reduce water usage by 2 million to 4 million acre-feet, according to a recent emergency request issued by USBR.