I googled it and it looks like ~80% of their water comes from within the state, and the rest mostly comes from Colorado, and I guess those guys wouldn’t object to a water deal even in case of secession. Not sure if secession is even possible in US though.
I have never met anyone who has read Alastair Reynolds’ Revelation Space series. It’s one of my favourite sci-fi’s and I can’t even get someone I know to read it, everyone thinks it’s boring :)