For the second year in a row, the US states of Arizona and Nevada will face cuts in the amount of water they can draw from the Colorado River as the Western United States endures an extreme drought, federal officials have announced.
The cuts planned for next year will force states to make critical decisions about where to reduce consumption and whether to prioritise growing cities or agricultural areas.
They will also place state officials under renewed pressure to plan for a hotter, drier future and a growing population. Mexico will face cuts, as well.
“We are taking steps to protect the 40 million people who depend on the Colorado River for their lives and livelihoods,” said Camille Touton, US commissioner of the Bureau of Reclamation.
The river provides water across seven states and in Mexico and helps feed an agricultural industry valued at $15bn a year. Cities and farms are anxiously awaiting official estimates of the river’s future water levels that will determine the extent and scope of cuts to their water supply.
That’s not all. In addition to those already-agreed-to cuts, the Bureau of Reclamation said on Tuesday that states had missed a deadline to propose at least 15 percent more cuts needed to keep water levels at the river’s storage reservoirs from dropping even more.
For example, officials have predicted that water levels at Lake Mead, the nation’s largest manmade reservoir, will plummet further. The lake is currently less than a quarter full. “The states collectively have not identified and adopted specific actions of sufficient magnitude that would stabilize the system,” Touton said.
After putting last year’s burden on the agricultural industry, Arizona officials will have to decide whether to spread additional pain to growing cities that rely on the river. The cuts are not expected to have a tangible effect on Nevada, which has already implemented the region’s most aggressive conservation policies, including grass bans and rebate programmes.
While the Bureau of Reclamation is “very focused on just getting through this to next year”, any cutbacks will likely need to be in place far longer, said University of Oxford hydrologist Kevin Wheeler.
“What contribution the science makes is, it’s pretty clear that these reductions just have to have to stay in place until the drought has ended or we realise they actually have to get worse and the cuts have to get deeper,” he said.
The cuts are based on a plan the seven states as well as Mexico signed in 2019 to help maintain reservoir levels. Under that plan, the amount of water allocated to states depends on the water levels at Lake Mead.
Last year, the lake fell low enough for the federal government to declare a first-ever water shortage in the region, triggering mandatory cuts for Arizona and Nevada as well as Mexico in 2022.
Officials expect the falling lake levels to trigger additional cuts to Nevada, Arizona and Mexico next year. States with higher priority water rights are not expected to see cuts.
Reservoir levels have been falling for years — and faster than experts predicted — due to 22 years of drought worsened by climate change and overuse of the river.
Scorching temperatures and less melting snow in the spring have reduced the amount of water flowing from the Rocky Mountains, where the river originates before it snakes 2,334km (1,450 miles) southwest and into the Gulf of California.
Already, extraordinary steps have been taken this year to keep water in Lake Powell, the other large Colorado River reservoir, which sits upstream of Lake Mead and straddles the Arizona-Utah border. Water from the lake runs through Glen Canyon Dam, which produces enough electricity to power between 1 million and 1.5 million homes each year.
After water levels at Lake Powell reached levels low enough to threaten hydropower production, federal officials said they would hold back an additional 480,000 acre-feet (more than 156 billion gallons or 592 million cubic metres) of water to ensure the dam could still produce energy. That water would normally course to Lake Mead.
Under Tuesday’s reductions, Arizona will lose slightly more water than it did this year, when 18 percent of its supply was cut. In 2023, it will lose an additional 3 percent, an aggregate 21 percent reduction from its initial allocation.
Mexico will lose 7 percent of the 1.5 million acre-feet it receives each year from the river. Last year, it lost about 5 percent. The water is a lifeline for northern desert cities including Tijuana and a large farm industry in the Mexicali Valley, just south of the border from California’s Imperial Valley.
Nevada also will lose water — about 8 percent of its supply — but most residents will not feel the effects because the state recycles the majority of its water used indoors and doesn’t use its full allocation. Last year, the state lost 7 percent.