What are we doing?

Just started reading (listening) to a book entitled Animal, Vegetable, Miracle. I'm already ready to move out of the city or at least plant a garden and shop local.

The author starts the book by explaining that she and her family are moving from Tucson to Southern Appalachia. Her husband owns a family farm that they have visited each summer of their married life. Now they are going to live there.

She points out two things that are troubling. One is that they (I guess the state of AZ) built a 300 mile open channel from the Colorado River to Tucson. Water is now diverted for the people's consumption though they were instructed not to use the water in their fish tank as it would kill the fish. As the water moves from the Colorado to Tucson, much water evaporates and leaves muddy, more mineral-concentrated water arriving in Tucson. (So I think in Tucson, people should be encouraged to drink bottled water. )

The other is that once upon a time the Colorado would empty into the Pacific Ocean. Now it barely makes it into Mexico. We are diverting that much water for both agriculture and human consumption. Tucson was initially taking water from an underground aquifer, but after much of it was depleted and sink holes started to make their appearance, they sought other means.

It seems like we are sorta stealing. Maybe even just outright stealing. What gives us the right to do this? Why should we keep doing this? How long will we be able to keep this up? How will we ever replenish the water for the river? Is it ok if we don't? What else are we stealing?