I don't know about the rest of the US, but I know in the midwest a pretty decent portion of the population get their water supply from the Ogallala Aquifer (htt

I don't know about the rest of the US, but I know in the midwest a pretty decent portion of the population get their water supply from the Ogallala Aquifer (https://en.wikipedia.org/wiki/Ogallala_Aquifer https://en.wikipedia.org/wiki/Ogallala_Aquifer). According to that link it's as much as 82% of the High Plains population.