California gets the rights to the first million acre feet of water out of Hoover Dam (at the border between Arizona and Nevada, California doesn't even touch the river at that point) before Arizona gets a drop. In a drought year they may not get any water at all. Arizona filed suit but it literally took decades to get the issue resolved. In the meantime Arizona built the Central Arizona Project. I don't think they ever got all the water they wanted/needed. There was, and is, a lot of bitterness between the states about it.
More to the point, California has consistently pulled more water out of the Colorado River than their allocation allows for decades. If California were limited to the water they’re allowed, there would be some serious disruptions in the urban water systems, since that is where the over-diversions are.
This is why SoCal cities keep hitting on the Imperial Valley Irrigation District to lease ag water rights.
I have a home in Scottsdale. The Salt River Project provides irrigation and power generation. Water is going to become an issue as the rapidly growing population of AZ has increased demand significantly. There will not only be battles among states but also betweeen Agribusiness and domestic use of water.