The Colorado River's Precarious Reservoirs

The Colorado River's Precarious Reservoirs

The Colorado River is one of the most important sources of water in the western United States.

However, its future is uncertain due to climate change and prolonged droughts.

Lakes Powell and Mead, two of the largest reservoirs on the Colorado River, are currently at 25-30% of their capacity.

Despite heavy snowpack in the river's Upper Basin states this year, they are unlikely to ever fill again, according to several water experts.

Brad Udall, a climate scientist at Colorado State University, and Eric Kuhn, a water researcher, suggest that it would take another four or five consecutive years of high flows like this year to fill Powell and Mead again.

But with the river carrying about 20% less water each year than it did during the 20th century, that's highly unlikely.

The lack of soil moisture due to hot, dry springs and summers has repeatedly held down runoff into Lake Powell in recent years.

However, this year's heavy snowpack is expected to produce the river's second-highest annual flow of the 21st century.

Paul Miller, a hydrologist for the federal CRBFC, believes it could take six to eight years like this one to refill all the reservoirs in the river's Upper Colorado River Basin, plus Lake Mead in the Lower Colorado River Basin.

But "probably isn't very likely," he said.

The bureau is studying two alternatives for curbing consumption of river water by the Lower Basin states of Arizona, California, and Nevada by 2 million to 4 million acre-feet a year.

Such reductions are needed to ensure the lakes don't fall so low that their dams can no longer generate electricity.

The reservoirs' situation may not be hopeless even if they don't refill.

It's still possible the river could get enough consecutive years of better than average flows to give the Colorado a breather and stave off drastic cuts for a while.

The last time both reservoirs filled was in the mid-1980s.

Since then, the Colorado River Basin, along with the entire Southwest, has suffered through its worst drought in 1,200 years.

Udall noted that over the past decade or so, a pattern has developed in which very wet years were followed by one or more very dry years.

Climate change can provide very wet years, but they will not make up for the more frequent hot and dry intervening years.

This year's heavy runoff into the Colorado River will significantly boost water levels at the big reservoirs of Lakes Mead and Powell.

However, both lakes will end 2023 lower than they were at the end of the river's last good runoff year of 2019.

Despite this year's good runoff, Powell will still be only 39% full and Mead 24% full.

That compares to 99% full at the turn of the century.

The future of the Colorado River is concerning, and experts suggest that more needs to be done to preserve this vital resource.