An irrigation canal reflects dawn-stained skies over Imperial Valley, a fertile farming region just north of Baja California.

The canal brings Colorado River water to the dry Salton Sea watershed, which, with an average of three inches (seven centimeters) of rainfall a year, would otherwise revert to desert. The Imperial Valley’s half million acres (202,343 hectares) of croplands soak up more water than Los Angeles and Las Vegas combined.

(Text adapted from and photo shot on assignment for, but not published in, “Salton Sea,” February 2005, National Geographic magazine)