What would happen is people would start farming where water is essentially free from the sky again. Huge swathes of the midwest require no or very tiny amounts

What would happen is people would start farming where water is essentially free from the sky again. Huge swathes of the midwest require no or very tiny amounts of irrigation for crops. But currently huge swathes of that land sit fallow and unused because people farming in the desert get essentially unlimited water on top of their near year-round growing season and can out compete them, which doesn't take much with how tiny farming profit margins are for most crops.