A proposed 2015 sale of Arizona water to California that never happened is now a flash point in a controversy pitting Arizona’s top water agency against the Central Arizona Project. A newly disclosed memo from that year, written by a CAP attorney, characterized the proposal as a sale of some of Arizona’s Colorado River water to the giant, six-county Metropolitan Water District in Southern California. Such a sale would be controversial in Arizona, given the longstanding adversarial relationship over water between the two states.