Ross D. Franklin/AP
SALT LAKE CITY — The federal government is expected to announce water cuts Tuesday in states that rely on the Colorado River as drought and climate change allow less water to flow into the river and deplete the reservoirs that store it.
The Colorado River provides water to 40 million people in seven western US states as well as Mexico and helps fuel an agricultural industry valued at $15 billion a year. Towns and farms across the region are eagerly awaiting official hydrological projections — estimates of future water levels in the river — that will determine the extent and scope of cuts to their water supply.
Water officials in Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming expect federal authorities to project Lake Mead – located at the Nevada-Arizona border and the largest man-made reservoir in the United States – reaching dangerously low levels that could disrupt water supplies and hydroelectric generation and reduce the amount of water allocated to Arizona and in Nevada, as well as in Mexico.
And that’s not all: State officials are also working to meet a deadline imposed by the United States Bureau of Reclamation to reduce their water consumption by at least 15% in order to prevent levels of water in the river’s storage tanks to drop even further.
Together, the cuts projections and deadline present western states with unprecedented challenges and confront them with tough decisions about how to plan for a drier future.
While the Bureau of Reclamation is “very focused on getting into next year”, any reductions will likely need to be in place for much longer, said Kevin Wheeler, a hydrologist at the University of Oxford.
“What the science is providing is that it’s pretty clear that these cuts just have to stay in place until the drought ends or we realize they actually have to get worse and the cuts have to go down. ‘deepen,’ he said.
The reductions expected to be announced on Tuesday are based on a plan that the seven states plus Mexico signed in 2019 to help maintain reservoir levels. Under this plan, the amount of water allocated to the states depends on the water levels at Lake Mead. Last year, the lake sank 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 hydrologists to project the lake to collapse further, triggering additional cuts in Nevada, Arizona and Mexico next year. States with higher priority water rights should not suffer reductions.
Reservoir levels have been falling for years – and faster than experts had predicted – due to 22 years of drought exacerbated 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 rises before meandering 1,450 miles (2,334 kilometers) southwest and into the Gulf of California.
Already, extraordinary steps have been taken this year to keep water in Lake Powell, the Colorado River’s other major reservoir, which sits upstream from Lake Mead and straddles the Arizona-Utah border. Water from the lake passes through the Glen Canyon Dam, which generates enough electricity to power between 1 million and 1.5 million homes each year.
After Lake Powell water levels fell low enough to threaten hydroelectric generation, federal officials said they would withhold an additional 480,000 acre-feet (more than 156 billion gallons or 592 million cubic meters) of water to ensure the dam can still generate power. . This water would normally flow to Lake Mead.
As part of Tuesday’s cuts, Arizona is expected to lose slightly more water than it did this year, when 18% of its supply was cut off. In 2023, it will lose another 3%, an overall reduction of 21% compared to its initial allocation. Central Arizona farmers will largely shoulder the cuts, as they have this year.
Mexico is expected to lose 7% of the 1.5 million acre-feet it receives annually from the river. Last year it lost about 5%. Water is a lifeline for northern desert towns, including Tijuana and a major agricultural industry in the Mexicali Valley, just south of the border with California’s Imperial Valley.
Nevada is also on the verge of losing water – about 8% of its supply – but most residents won’t feel the effects because the state recycles the majority of its water used indoors and n does not use all of its allocation. Last year, the state lost 7%.