It’s an export to Saudi Arabia IIRC. It’s basically a matter of agribusiness exploiting water rights laws intended to support yeoman farmers over a century ago to cheaply grow a shitty cash crop for export as IIRC horse and camel feed. They get to use functionally unlimited water for nothing/next to nothing and the state can’t stop them or even force them to pay its actual value (which would make the whole thing nonviable).