How California Atmospheric River Will Impact Colorado River Basin

An atmospheric river due to hit California in the coming days is not likely to help the situation in the Colorado River Basin, an expert has told Newsweek.

The atmospheric river—a corridor of concentrated, tropical moisture traveling through the atmosphere—is the latest to hit the state in recent months. The river has the potential to cause severe flooding across the state, with experts warning of severe disruption. When atmospheric rivers make landfall, they release vapors as either rain or snow. This can cause severe conditions, and has previously led to mudslides in the state.

From late December 2022 to January 2023, California saw nine atmospheric rivers, which caused winter storms to sweep across the state. There was heavy rain in wider areas across the southwestern U.S., but California was hit the worst. During this period, more than 32 trillion gallons of water descended on California—not including recent storms and blizzards that hit the state at the end of February.

California is one of the Colorado Basin states—along with Arizona, New Mexico, Colorado, Utah, Nevada, and Wyoming—that rely on the Colorado River as a water source.

Colorado River from above
A stock photo shows the Colorado River from above. The rains to batter California recently will not improve the problems in the basin states. Eminaldo/Getty

The megadrought currently gripping the southwestern U.S. is causing the Colorado River—and its reservoirs such as Lake Mead—to dry up. The influx of wet weather may have raised hopes among locals that it will help the situation.

But despite the increased rain and snow in the region, Elizabeth Koebele, a professor of political science at the graduate program of Hydrologic Sciences at University of Nevada, Reno, told Newsweek that the Colorado River's situation is likely to stay dire.

"Although many areas of the western U.S. have received above-average precipitation over the 2022-2023 winter, the Colorado River situation has become so dire that it will not be resolved with one year—or even a few years—of good hydrology," Koebele said.

As the southwest has been in a drought for so long, it will take many years to fully lift this status and get water levels up to where they should be.

"It's easy to forget just how bad things have gotten when we're getting a lot of snow in the region, but policy makers need to keep the long-term trend toward aridification in the forefront of their mind when governing this system," Koebele said.

The wet weather has alleviated the drought in some areas of California. But this is likely to be only temporary.

Tom Corringham, research economist at the Scripps Institution of Oceanography at UC San Diego, told Newsweek that California is likely to see droughts continuing due to past effects of climate change.

"A warmer atmosphere holds more of the water vapor that drives extreme storms, including atmospheric rivers. As the world warms we expect to see longer, wider, and wetter atmospheric rivers," Corringham said. "If we don't rapidly zero out greenhouse gas emissions, atmospheric rivers could triple flood damages in the coming decades. If we can cut emissions we may be able to limit the increase in damages."

"However, because of past emissions, we're now committed in California to a new normal of severe droughts punctuated by extreme floods. In addition to reducing greenhouse gas emissions, we must invest in resilience to protect our most vulnerable communities."

The wet weather has massively helped replenish California's reservoirs, which were in a dire state during the dry, summer months. But this atmospheric river due to hit the state in recent days may do more harm than good.

Experts are predicting that the atmospheric river will be warm, meaning it could melt the accumulated snowpack faster than the state can prepare itself.

And with the increased level of snowpack this year, this means floods are highly likely.

The snowpack in the Sierra Nevada mountains has continued to increase throughout January as a result of storms battering much of the state. As of March 1, the northern Sierra Nevada precipitation index is at 43.5 inches, compared to the water-year average of 53.2.

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