Nation ‘Red alert’: Lake Mead falls to lowest water level since Hoover Dam’s construction in 1930s June 10, 2021Ian James, Arizona RepublicComments Off on ‘Red alert’: Lake Mead falls to lowest water level since Hoover Dam’s construction in 1930s Lake Mead declined to its lowest level since Hoover Dam's construction in the 1930s. It's a new milestone for the water-starved Colorado River.