Not all of Phoenix's water comes from the Colorado (and in fact not most of it I don't believe). Phoenix is sometimes called "Valley of the Sun". Well, it's no

Not all of Phoenix's water comes from the Colorado (and in fact not most of it I don't believe). Phoenix is sometimes called "Valley of the Sun". Well, it's not in the mountains, (there are some low mountains around I guess but not really "mountains"). It's called a valley because it's a river valley at the con-flux of several smaller rivers (the Gila, the Salt). Granted these are kind of dry most of the time but water flows underground also. So there are a lot of wells. And water comes from rain and snow melt in the mountains to the north. To your point though it still isn't sustainable at growing population levels. My understanding that much of the well water used is from rain that fell during the last ice age. That's why they call it Phoenix probably. One day it will burn up. But this is a futuristic city on the outskirts. Presumably it will have a sustainable water supply created with cosmic zeolith ions, heavy duty science and good karma :)