Arizona's farmland is set to get drier after the federal Bureau of Reclamation announced Tuesday the state must cut back 21% of its Colorado River water supply. Federal officials will reportedly reduce Arizona's river water usage by 592,000 acre-feet. One acre-foot of water would generally supply three average Phoenix households with water for a year. The announcement comes off the back of the bureau's latest Colorado River Basin study that projected Lake Mead would reach its lowest elevation ever in Jan. 2023, triggering the lake's first-ever Tier 2a shortage.