Federal officials on Tuesday announced the first-ever “Tier 2” water shortage for the lower Colorado River Basin — a designation that triggers new water use reductions for Arizona, Nevada and neighboring Mexico next year. 

The nation’s two largest reservoirs, Lake Mead and Lake Powell, are now at 28% of their full capacity, an historic low, and continue to shrink amid a 23-year climate-fueled “megadrought.” Researchers have concluded that the U.S. Southwest is experiencing its driest spell in at least 1,200 years.