The federal government announced new limits Tuesday on how much water the Southwest can take from the shrinking Colorado River and top officials were clear about the stakes.
"To avoid a catastrophic collapse of the Colorado River system and a future of uncertainty and conflict, water use in the basin must be reduced,” said Tanya Trujillo, assistant secretary for water and science in the Interior Department.
Two decades of drought and the growing effects of climate change have pushed the river beyond its limits. The two largest reservoirs, Lake Powell and Lake Mead, sit at one-quarter full and water levels have fallen at a pace that has surprised many of the experts.
The government's operating guidelines were based on existing agreements among the seven states that draw water from the river, so there were no real surprises. Arizona, Nevada and Mexico will feel the brunt of the restrictions and, in Arizona, farmers will take the deepest cuts.
Here are five key takeaways from Tuesday's announcement:
1. Water level data tells a bleak story
The revised operating guidelines were expected because they're based on data, specifically the water levels at Lake Mead and Lake Powell. The numbers helped illustrate the risks of waiting too long.
The Bureau of Reclamation projects that Lake Powell will sit at 3,522 feet above sea level on Jan. 1. That's just 32 feet above the minimum level needed to run the power plant at Glen Canyon Dam.
If the lake drops below that minimum, the turbines will shut down. That would mean the loss of electric power and force the bureau to shore up other ways to keep water flowing through the dam downstream to Lake Mead. If water can't get past Glen Canyon Dam, the Colorado would no longer flow through the Grand Canyon.
Lake Mead will start 2023 at a physical elevation of just under 1,041 feet above sea level. That's 25 feet lower than Jan. 1, 2022, and 173 feet lower than Jan. 1, 2000, when the two reservoirs were at capacity.
The bureau will monitor all these numbers through 2023 and could adjust river operations if water levels don't rebound.
2. Arizona, Nevada and Mexico will take biggest hits
Starting Jan. 1, Arizona will reduce the amount of water it takes from the river by 592,000 acre-feet, or about 22% of the state's allocation. Nevada will lose 25,000 acre-feet and Mexico will give up 104,000 acre-feet.
California will not take any cuts as of now.
That arrangement is rooted in an agreement made decades ago when Arizona needed California's support to build the Central Arizona Project, the canal that moves water from the Colorado River to Phoenix, Tucson and Pinal County. Arizona agreed to assign that water lower priority rights, which would delay cutbacks in California.
The cuts announced Tuesday were a part of a 2007 drought response plan and a more recent drought contingency plan.
Arizona officials would like to see other states absorb some of the pain if the feds seek deeper cuts in the next few years, but so far, negotiations have failed.
"It is unacceptable for Arizona to continue to carry a disproportionate burden of reductions for the benefit of others who have not contributed," said Tom Buschatzke, director of the state water resources, and Ted Cooke, general manager of the CAP.
3. Most Arizonans won't face water limits
Once again, Arizona farmers will take the hardest hit from water cutbacks. Starting Jan. 1 of this year, growers in Pinal County lost their access to water from the CAP and that won't change in 2023.
Most Arizona cities deliver a mix of water from the Colorado River and the Salt and Verde rivers, where conditions are better. Even if there is less water for municipal providers — and it's not known if that will be the case — the cities have a cushion that will protect residential users from cutbacks.
Phoenix declared what it called a Stage 1 Water Alert, but focused on water conservation steps, especially outdoors. City officials don't anticipate any mandated limits on use in the coming year.
The CAP doesn't supply cities outside Maricopa, Pinal and Pima counties.
Arizona lawmakers earlier this year approved a plan to spend more than $1 billion to augment water supplies and encourage conservation.
4. Tribal communities will continue to play a role
As Arizona and other states have discussed ways to stretch the river's supply, they have been joined at the table more frequently by leaders of tribal communities, who have leveraged their own allocations to delay deeper cutbacks.
The Colorado River Indian Tribes and the Gila River Indian Community have both previously left portions of their river shares in Lake Mead, helping maintain water levels in the reservoir and ensuring that Arizona could meet its obligations under a drought contingency plan.
But Gila River officials said Tuesday they were dissatisfied with the pace of negotiations and have decided to re-evaluate their involvement, storing water underground rather than leaving it in the reservoir.
And some tribal leaders voiced concerns that they were being left out of the latest round of talks and wrote a letter to the Interior Department, seeking to protect their interests as water use is curtailed.
Tribal communities were excluded from major decisions regarding water for decades, from the first major agreement on the river, the 1922 Colorado River Compact.
5. Interior Department left door open for more cuts
Testifying before a Senate committee in June, Camille Calimlim Touton, commissioner of the Bureau of Reclamation, said the Colorado River system had reached a tipping point and told lawmakers significant conservation measures would be required to protect water users and infrastructure. She suggested the seven states might have to cut 2 million to 4 million acre-feet, a level the states feared they could not achieve.
On Tuesday, the government outlined a plan that would reduce deliveries to Arizona, Nevada and Mexico by a combined 721,000 acre-feet, amounts agreed to earlier by the states, but did not demand any further reductions immediately.
But the bureau made it clear that depending on snowpack and runoff in the coming winter seasons, more conservation would be required, with cutbacks in the range of 600,000 to 4.2 million acre-feet a year.
Arizona's annual allocation is 2.8 million acre-feet.
This article originally appeared on Arizona Republic: Colorado River water plan: 5 things Arizonans need to know