It seems to me that if you need to dig a well that deep you have utterly failed to address the real problem: you are using MUCH more than falls on the ground. Wait a few more years and you'll just have to dig an even deeper well. It's just postponing the inevitable. [1]
With that principle in mind, I'm not sure I care if deep resources are polluted for a few hundred thousand years.
[1] Mexico is rapidly improving economically; it may make sense for them to postpone the real solution until such time as they can afford to desalinate and ship water long distance.
Just a note in Mexico. It can be divided two parts with different water problems. In central and southern Mexico, there is abundance of rain, and it is more populated. The main problem is managing the rain. Northern Mexico is like the American Southwest, sparsely populated, great extensions of land and very little rain.
With that principle in mind, I'm not sure I care if deep resources are polluted for a few hundred thousand years.
[1] Mexico is rapidly improving economically; it may make sense for them to postpone the real solution until such time as they can afford to desalinate and ship water long distance.
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