Fact is So Cal is using the Colorado River at a greater than 100% rate. Half of LA is going to have to leave or pay through the nose to desalinate ocean water. Nature is gonna force the choice.
Just take the money for the "fast choo-choo" and use it to process seawater instead. That would actually be a valid use of the $$!
Of course, it being California, nothing sensible like that is ever going to happen.