See How Much Water Has Disappeared From Lake Mead in the Past 30 Years

The water level in Lake Mead, the country’s largest man-made reservoir, reached its lowest point on record this week, according to government numbers.

The record follows years of drought in the region that has threatened water supplies for millions in Arizona, Nevada and California that depend on it. Images of the lake from the ground-level have become commonplace and show bathtub-like rings indicating the drop in water levels. But aerial images are in some ways more illustrative of the change.

The two images above compare water levels from 1984 and 2016. The lake had recently neared full capacity in the summer of 1983. Today, it is at 37% capacity.

Read more details on the decline in Lake Mead water levels here.