Rights to use the Colorado’s water are governed by nearly a century of agreements among states, the federal government and Mexico, a legal document collectively known as the Law of the River. The Bureau of Reclamation on Monday declared a Tier 1 shortage.
Arizona’s annual allotment will be cut by 18 per cent starting next year. Nevada and the nation of Mexico will incur reductions of 7 per cent and 5 per cent, respectively. (The other states that draw water from the river are California, Colorado, New Mexico, Utah and Wyoming.)
Arizona’s reduction will be equivalent to the amount used by about 1 million average households in a year. The cuts will not affect any municipal, industrial, commercial or tribal users. Instead, almost all the cutbacks will fall on farms that receive their water from the Central Arizona Project.
The rationing will likely hit hardest in Pinal County, where farmers tend to have the most junior water rights. Farms there will have to let lands go fallow or rely on groundwater that’s already over pumped. While Arizona is trying to cushion the blow by building out groundwater infrastructure, some observers say the cuts will provoke litigation.
“Pinal County agriculture faces a dire reality,” the Arizona Farm Bureau said in a statement. “This will have a devastating impact on each farming family in that county, and the surrounding communities will feel the ripple effects for years to come.”
Tom Buschatzke, director of the Arizona Department of Water Resources, said some of the water the state will be losing has been stored underground and can now be used to mitigate the shortfall. Many Central Arizona Project farms in Pinal, Pima and Maricopa counties “will be losing substantial amounts of their surface water, and we’ll be able to offset their losses by pumping groundwater under our Groundwater Management Act,” he said, during Monday’s press conference.
John Entsminger, general manager of the Southern Nevada Water Authority, said his agency has “pre-conserved” the cuts it will be seeing in 2022, meaning there will be no reductions in water to its member agencies.
Should the drought continue next year, California could face supply reductions: the Golden State must forgo water when Lake Mead falls below 1045 feet.
That’s a strong possibility. The US Climate Prediction Centre last week forecast a 62 per cent chance that the La Nina phenomenon in the Pacific Ocean would return this northern autumn, its second appearance in two years. La Nina typically brings dry winters to the south-west. While the summer monsoon season this year has brought frequent thunderstorms, they have not made a dent in the drought. And with climate change, many long-term models predict a more arid future for the region.
“The possibility of back-to-back La Nina years is always there, and we’ve had them before,” said Park Williams, a climate scientist at the University of California, Los Angeles. “Having that after a 21-year period where it’s been mostly dry is starting to put us up against the ropes.”