See How Far Water Levels in Lake Mead Have Fallen

The banks of the rivers that fed the lake were flooded in 2000. It has shrunken in 20 years. It's basins are almost teal in places, a sign that the waters are becoming more shallow.

The lake is now encircled by a puckered shoreline and a white shadow, the remnants of salts and minerals left behind on the canyon walls by the water.

The National Audubon Society's Colorado River program director said that the two large reservoirs on the Colorado River were full in the past. There are dangerously low levels throughout the Colorado River basin. The basin is close to a Day Zero situation.

Satellite imagery shows how much the Southwest has been affected by the dry spell. 25 million people in seven states and some of the country's largest agricultural valleys rely on Lake Mead for their water needs.

The federal government is trying to conserve water in the Colorado River basin. The federal government declared a water shortage at the lake last summer. In response to worsening conditions, the Bureau of Reclamation, which manages water and power in the West, issued an emergency request to states to propose immediate cuts to the water supply.

Image

The images show the driest two-decade period since A.D. 800.

Human-caused global warming has been found to be a factor in the continuation of the current dry spell. It's possible that rising temperatures, more than rain and snow conditions, are the reason for the current dry spell.

NASA wrote in a statement accompanying the images that they show a stark illustration of climate change and a long-term drought that may be the worst in the U.S.

The lake is at its lowest level since 1937. Ms. Pitt said that the water supply downstream was lower because of the dead pool.

The water level at the Hoover Dam has fallen 158 feet in the last two decades, according to the Bureau of Reclamation. The level of the lake needs to stay above 1,000 feet.

The Colorado River Watershed gets a lot of snow in the Rockies. This year has been below average in the amount of water in the ground.

Henry Fountain made a report.