New rules for the Colorado River officially go into effect on Thursday, but they won’t bring changes to Arizona’s water quite yet. The state is still working on a three-way deal with California and Nevada to spread out the pain of water cutbacks. Arizona’s water cuts will become official on Jan. 1, 2027, and Arizona’s top water negotiator told KJZZ he’s “very optimistic” about progress on the three-state deal that must be signed by then.
To understand the complicated timeline for new water rules, it helps to take a step back and look at the Colorado River’s complicated calendar.
Federal rules for the Colorado River and its major reservoirs typically run on a different calendar than the rest of the world. The “water year” runs from Oct. 1 to Sept. 30. So, starting Thursday, a controversial federal plan will start changing the amount of water sent from Lake Powell downstream to Lake Mead…