Here's what will happen if Colorado River system doesn't recover from 'historic drought'

The Colorado River, one of the most important river systems in the country, is drying up at an alarming rate.

The issues surrounding depleting water levels along the Colorado River basin have become as heated as the arid climate contributing to the moisture-sapping megadrought persisting in the region for decades.

Despite an extremely wet winter that eased the effects of the longstanding drought, regional officials and environmental experts are expressing concern over future severe dips in the water supply and other ramifications dwindling water levels could have on local economies and human health.

The Colorado River is now considered the more endangered river in the world by conservation nonprofit American Rivers.

An ample water supply is a "critical component" of human health and public safety, Sinjin Eberle, Southwest region communications director for the nonprofit American Rivers, told ABC News.

"If there's not a healthy environment, we don't have healthy drinking water supplies, and we don't have healthy ecosystems and we don't have habitat for wildlife," Eberle said. "We don't have sustainability and we don't have certainty in the water supplies."

The Colorado River is one of the most important systems in the country

The Colorado River Basin supplies drinking water to 40 million people in the U.S., as well as two states in Mexico, according to the Bureau of Reclamation. It also fuels hydropower resources in eight states and remains a crucial resource for 30 Tribal Nations and agriculture communities across the West.

The river system supports $1.4 trillion of the annual U.S. economy and 16 million jobs in California, Arizona, Nevada, Utah, Colorado, New Mexico and Wyoming-- equivalent to about 1/12 of the total U.S. domestic product, economists at the University of Arizona found in 2015. More than 90% of the country's winter leafy greens and much of its vegetables are grown in Yuma, Arizona -- the state that would experience the most drastic water cuts under current regulations.

Lake Mead was producing 25% less hydroelectricity as its elevation reached a record low at 1,067 feet in December 2021. The reservoir was dangerously close to hitting dead pool status, when water levels are too low to flow downstream to generate power, last June as surface elevation measured in at just 1,043 feet.

This past March, water levels in Lake Mead measured at 1,046 feet, according to the Bureau of Reclamation.

Dead pool status is "not far in the future," and could possibly happen this decade, in the event of five or six consecutive dry winters, Zach Zobel, risk scientists at the Woodwell Climate Research Center, told ABC News.

If the West is not diligent in learning to live within the water system, it could have "serious ramifications" on other sectors, such as the semiconductor industry in Phoenix, a billion-dollar industry that provides tens of thousands of jobs in Arizona, Eberle said.

Without water from the Colorado River, Arizona's gross state product would drop by more than $185 billion in a year and the state would lose more than 2 million jobs, the 2015 report found.

In addition, electricity bills and water bills have the potential to skyrocket, and the region will need to consider building infrastructure for other power sources, such as solar and wind, Eberle said.

"Even more alarming" is that water could get so low that it can not be pumped and delivered to the states, communities and agricultural industries that rely on it, Richard Frank, professor of environmental practice at the University of California Davis School of Law, told ABC News.

The dip in water levels is widely due to climate change

Over the past 20 years, the West has been undergoing a substantial period of drought, much of it driven by anthropogenic, or human-caused, climate change, according to experts.

For every 1 degree Celsius in temperature rise, flow along the Colorado River has dipped 9.3%, scientists with the U.S. Geological Survey announced in 2020. This has led to the depletion of 1.5 billion tons of water, much of is lost to evaporation or lack or melting snowpack, according to the study.

The Colorado River has about 19% less volume than in the year 2000, Eberle said. By 2050, that number is expected to drop to 30% less than in 2000 if temperatures continue to rise, he added.

The Colorado River is over-allocated, experts say

In 1922, the Colorado River Compact divvied up the river's water -- as to how the water supplies from the Colorado River and its tributaries would be allocated -- among the seven states that rely on it. The upper basin states were established as New Mexico, Utah, Wyoming and Colorado, while the lower basin consists of California, Nevada and Arizona. Two states in Mexico -- Baja California and Sonora -- were added to the Compact in the 1940s.

However, the amount of water that was apportioned "was not consistent" and "exceeded significantly" the amount of water that was actually available, even by 1922 standards, Frank said.

"There were overestimations of how much water there would be to allocate among the states," Frank said. "So it was a flawed premise to begin with."

At the time of its inception, those in charge of dividing the water resources assumed they were working with a 17-million acre-foot river, based off an extremely wet period in the beginning of the 20th century, Eberle said. These days, the river is closer to 12 or 11 million acre-feet, he said.

When the contract was signed, there were only about half a million people living in the basin. Fast-forward to the 21st century, and a population explosion in the region with three of the largest cities in the country that rely on the Colorado River -- Phoenix, San Diego and Los Angeles -- has grown that number to more than 40 million, Eberle said.

Climate change over the past century has only worsened the inevitable problem, Frank said.

"So we have an additional challenge of less water availability at a time when we are we're attracting more people who want to reside in the Southwest," Frank said. "That's a problem."

Even in the absence of climate change, the Colorado River would likely be in decline due to the population growth, Zobel said.

1 year of heavy precipitation isn't enough to solve problem

At the start of the fall, the visual evidence of overallocation, combined with years of severe drought, was striking along the Colorado River system. Prominent bathtub rings showing where water levels once were could be seen in Lake Mead and Lake Powell. Parts of Lake Mead were so dry that human remains began to emerge in riverbeds once covered in freshwater.

Then, as winter rolled in, an "amazing and completely unpredicted series of events" occurred, Eberle said.

A series of atmospheric rivers -- essentially rivers in the sky that collect moisture from tropical areas and redistribute the water to other latitudes -- have been pummeling the West Coast with an influx of precipitation since December, bringing round after round of heavy rain and snow to the parched region.

"The snowpack is amazing, and in some ways it kind of takes the foot off the gas in terms of how dire things could be," Eberle said, but added that water levels could just as easily dip to record lows a year from now if urgent measures aren't taken to conserve water.

In the future, the trend will be for greater, longer, more protracted droughts interrupted occasionally, by periods of plentiful rainfall, scientists say.

This year will be an "important case study" on how much of the water that was lost in the past five years from the largest reservoirs can be recovered, Zobel said.

"If things can't recover in the good years, then the situation is still not looking good for the future," Zobel said.

Climate scientists don't expect many "average" years of precipitation anymore, Zobel said. Instead, what will likely happen is either all of the precipitation will come at once, or none at all -- what is referred to the "boom or bust precipitation pattern," he said.

While atmospheric rivers are expected to occur more frequently as global temperatures continue to rise, relying on the uncertainty that these events could occur again is not an adequate management strategy, Eberle said, especially since climate scientists expect snowpacks to trend much leaner in the future.

The influx of moisture into the coast has not yet been added to the water supply in the Colorado River system, but it will once the snowpack melts, the experts said.

In the sub-basin near Durango Colorado, the snowpack is about 180% above normal levels, Eberle said.

"That will bring a lot of water into Lake Powell and Lake Mead eventually," he said.

The immediate steps needed to maintain water levels

It will be up to the federal government to step in and encourage a tightening of water usage and address the imbalance between supply and demand, especially as the population in the Southwest, the fastest-growing region in the country -- continues to implode, the experts said.

The policy needs to include "major" water cuts, especially to the agriculture industry, Zobel said.

It would be "magical thinking" to assume that water from the Colorado River would be indefinitely available for the lower basin states, Frank said.

Officials may be coming to a consensus that too much water is leaving the Colorado River system.

On April 11, the U.S. Bureau of Reclamation announced it was considering a landmark proposal that includes scenarios to conserve water by reducing the amount of water released from Glen Canyon Dam or cutting water allotments evenly among all the lower basin states if basin states don't find a way to conserve 4 million acre feet of water in by 2024 -- or roughly 20% of current water usage -- a directive made by Bureau of Reclamation Commissioner Camille Calimlim Touton last summer.

"We're in the third decade of a historic drought that has caused conditions that the people who built this system would not have imagined," Tommy Beaudreau, deputy secretary of the Interior Department, told reporters on April 11.

Conversation among states to reduce water without federal intervention have become "very fractious and difficult," Frank said, adding that Mexico's entitlement further complicates matters.

The Interior Department will have the "ultimate say," Frank added.

The Biden Administration will also be providing a $15.4 billion investment to enhance the West's resilience to drought, which will include reducing water demand, maximizing water resources and protecting the communities along the Colorado River Basin.

Some of those solutions should include the modernization of agriculture industry systems, which uses up to 80% of the water supply in several regions, the experts said.

Water concerns are so rampant in Arizona that the city of Scottsdale cut off water delivery to Rio Verde Hills, an affluent neighborhood on the outskirts of the city.

"We have to address the imbalance between how much water there is, how much water there is going to be, and how much water is demanded for various aspects of life, like agriculture, drinking water in cities, and for recreation and water for the environment -- a key component of the sustainability of human health and public safety across the basin," Eberle said.

If the problem isn't solved, lack of adequate water supply will have a "profound effect" on communities and businesses in the West and the nation overall, Frank said.

"What does Tom Cruise say in 'Mission Impossible?' Hope is not a strategy," Eberle said.