From above, tiny green irrigation circles draw a narrow buffer along the 2,300-kilometer course of the Colorado River like the brush strokes of a zoomed-in pointillist painting. These vibrant green dots stand out against the buff and ochre hues of the desert palette, a testament to the river’s life-giving waters. Less obvious are the 6.4 billion cubic meters of water that flow, or are pumped, more than 390 kilometers from the Colorado’s gorge through tunnels and canals, up and down hills, to the agricultural and population centers of Southern California each year, and the additional 3.4 billion cubic meters that gurgle toward Phoenix and central Arizona annually.