Speculative Fact #164: Death By Irrigation

What happened in ancient Mesopotamia? It turns out that one reason for the area's decline was directly tied into one of the developments that helped them thrive (irrigation). 
    After being used on crops, the irrigation water would dry out and leave behind salt deposits. The salt deposits accumulate over time, salinating the ground and making it untenable for future crop growth.
    Flash forward to the future. The same irrigation methods are used in modern civilizations on much larger scales. Experts say the process takes centuries. A long amount of time for one person but a blink of the eye for a civilization.
    What will southern California and the American southwest look like hundreds of years from now? Will we take a lesson from dead civilizations and change our ways, or will we turn vast parts of our country into desolate wasteland? 

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