"The Colorado River and Hoover Dam: Facts and Figures" The Colorado River and Hoover Dam: Facts and Figures concrete in the Hoover dam "The Colorado River and Hoover Dam: Facts and Figures" "The Colorado River and Hoover Dam: Facts and Figures" Source The Colorado River and Hoover Dam Facts and Figures "The Colorado River and Hoover Dam: Facts and Figures" "The Colorado River and Hoover Dam: Facts and Figures" "The Colorado River and Hoover Dam: Facts and Figures" Colorado River and Hoover Dam Facts "The Colorado River and Hoover Dam: Facts and Figures" "The Colorado River and Hoover Dam: Facts and Figures"