A lack of snow in the Colorado River Basin is exacerbating an existing drought, and heralding future problems

United States

ON MARCH 13TH Denverites watched from frozen windows as the fourth-biggest snowstorm ever to hit their city buried Colorado’s capital two feet deep, and added fresh powder to the foothills of the Rockies. Local officials closed the main highway leading to the mountains lest eager skiers get trapped on icy roads on their way to the slopes. After a dangerously dry 2020 and a warm start to winter, the storm brought eastern Colorado’s winter snowpack (the accumulation of snow) up to average levels. When it melts, water will replenish thirsty reservoirs, rivers and soil. Not everywhere was so lucky. Much of the Mountain West watched the snow falling on Denver with envy.

Drought has afflicted a large swathe of the region for nearly a year (see map). The Colorado River Basin, which includes pieces of seven western states and part of Mexico, has been among the worst-affected areas. A warm spring in 2020 led snow in the mountains to melt early, which depleted the amount of water reservoirs and rivers received during the driest months of the year in summer and autumn. On top of that, the annual monsoons that the south-west depends on never came—and indeed have been lacklustre for four years. The combination of the early melt and a hot, dry summer led to a deadly wildfire season. Colorado and California both suffered their biggest fires on record last year.

Becky Bolinger, Colorado’s assistant state climatologist, says the West has endured multiple prolonged periods of drought since 2000, which have made it impossible for the country’s biggest reservoirs—Lake Mead in Nevada and Lake Powell on the border of Utah and Arizona—to fully recover (see chart). On March 15th the lakes were roughly two-fifths full.

Let it snow

The blizzard that buried Denver did nothing to help ease the drought on the other side of the continental divide. The Rockies split Colorado in two: the Front Range, where most people live on the high plains, and the Western Slope, where waters flow towards the Pacific. The Mountain Studies Institute, a research group in Silverton, estimates that western Colorado has warmed faster than any part of the country, except Alaska. On March 22nd snowpack in the south-western corner of the state was at 83% of its normal level for this time of year. That may not seem too bad, but the region needed above-average precipitation this winter to make up for the past year. Citing a lack of snow, Utah’s governor declared a state of emergency and urged Utahns to find ways to save water. The situation looks bleaker still farther south. Snowpack in parts of Arizona and New Mexico has fallen to less than 50% of average for this time of year.

Average snowpack has been decreasing for decades. Philip Mote, a professor of atmospheric sciences at Oregon State University, found in 2018 that annual snowpack in the American West has declined by 15-30% since 1915. But studying snow drought (and indeed using the term itself) is a recent phenomenon, says Dan McEvoy, a climatologist at the Western Regional Climate Centre in Reno, Nevada. He reckons that warmer winters due to rising carbon-dioxide emissions have made the droughts more frequent and harder to ignore. A lack of snow deprives soil and forests of essential nutrients. It also increases river temperatures and can heighten the risk and severity of wildfires. Unstable snowpack seems also to have contributed to an uptick in avalanche deaths this year.

It’s not just the environment that suffers for want of snow. The economies of many towns in the West are centred around the white stuff and the tourists that come in search of it. “In the ski industry, snow is currency,” says Auden Schendler, the vice-president of sustainability at Aspen Snowmass resort. Winter sports tourism is a $20bn industry in America for which snow drought is an existential threat.

Warm weather blues

Because drought is a perennial problem in the West, adaptation has become a way of life. Conserving water isn’t just a green fad; farmers and ranchers will not survive without it. Some farmers in Colorado and the Pacific Northwest are experimenting with farming without irrigation. State governments are also increasing aid to constituents whose livelihoods are threatened by drought. Colorado’s proposed $700m covid-19 stimulus plan includes up to $55m to fight drought and fire.

These adaptation strategies are a good start. But the future promises ever more complicated water problems. The current compact governing the use of the Colorado River is set to expire in 2026. The agreement, which was negotiated in 1922, called for “upper basin” states, where the river originates, to share water equally with “lower basin” states. Nearly a century later, the compact is showing its age. Today around 40m people depend on the river for water. States, tribes, the Mexican government, developers, environmentalists and farmers, among others, all want a say in how the water is allocated. The lower basin is also home to some of America’s fastest-growing cities, such as Phoenix and Las Vegas.

It would be hard enough drawing up a modern compact that satisfies so many competing interests. Add a shrinking water supply and growing populations, and a battle over the river looms. Individual states are already pressing their cases. Utah, for example, has created a controversial new agency to argue for more water on the state’s behalf. The fight over water, much like the West itself, is heating up.