February 5, 2023

The beginning of 2023 has brought severe storms across much of the southwestern United States. But despite the rain and snow, the water levels in the country’s two largest reservoirs are still well below average.

Lake Mead and Lake Powell are the largest and second largest water reservoirs in the United States, respectively. Both reservoirs are fed by the Colorado River, a 1,450-mile waterway that stretches from the Rocky Mountains to northern Mexico.

The river provides water for millions of people in the Southwest, but the US Geological Survey estimates that the river’s flow has decreased by 20 percent over the past century.

Lake Powell at record low
An aerial view of Lake Powell in June 2021. The tall, bleached “bathtub ring” on the rocky shore shows how low the water level is in this large reservoir.
Justin Sullivan/Getty

“The Colorado River has experienced prolonged drought for the past 23 years, made worse by climate change,” Jennifer Pitt, Colorado River program director for the nonprofit environmental organization National Audubon Society, previously said news week. “Rising temperatures are drying out the region, resulting in less current in the river.”

In early January, the city of Scottsdale, Arizona was forced to cut off its water supply to the Rio Verde foothills over concerns that allocated water supplies from the Colorado River would not be sufficient to support its own residents.

Fortunately, rain and snow in recent weeks have helped improve the state of the drought-stricken Colorado River, said Haley Paul, Arizona policy director at the National Audubon Society, previously news week. “These storms have delivered above-average snowpack and river flows for this time of year.”

But how has that affected the river’s main reservoirs?

Lake Powell water levels

Water levels in Lake Powell have been falling steadily since the summer of 2022. The water level is now at 3,524 feet above sea level, just 24 percent of its full storage capacity.

The reservoir hit a record low in April 2022, falling to 3,519 feet above sea level.

Lake Powell, which lies on the Arizona-Utah border, is fed primarily by snowpack runoff in Colorado, Utah, and Wyoming.

“Approximately 75 to 80 percent of the inflow into Lake Powell comes from runoff from melting snowpack that accumulates during the winter,” said Amee Andreason, a spokeswoman for the Bureau of Reclamation news week. “The remainder comes from rain during the non-winter months. Only water falling into the Upper Colorado River Basin flows into Lake Powell.”

Snow cover across Colorado is 130 percent of what it normally is this time of year, which is good news for the Colorado River and its reservoirs. However, Andreason said that “it will be several really wet years before there is enough inflow to Lake Powell to restore its water storage to pre-drought conditions.”

Lake Mead water levels

In July 2022, Lake Mead’s water level reached an all-time low of 1,040 feet. The water level has risen very slightly in the past few weeks, from 1,045 feet in early January to 1,046 feet today. The increase is likely due to the heavy rain that swept through California and Nevada during this period.

Record lows in Lake Mead
Photo of a boat surfacing at record low tide on Lake Mead, the largest man-made reservoir in the United States. The water level has risen very slightly, from 1,045 feet in early January to 1,046 feet today.
David McNew/Getty

But that’s still only 29 percent of the lake’s full storage capacity. Additionally, a study released by the Bureau of Reclamation last week suggests the reservoir could hit a new all-time low in 2023.

Recent rain and snow gave a hopeful sign for the coming year, but more than a few weeks of wet weather are needed to ease the decades-long mega drought that has swept the US Southwest.

“Water supply projections appear to be higher than average,” Paul said. “But remember, because our reservoirs – particularly Powell and Mead – are so low after over 23 years of drought, it would take many years of above-average snow and runoff to refill the reservoirs.

“We can’t take our eyes off the ball when it comes to figuring out how to use less water from the Colorado River to keep the reservoirs from falling to catastrophically low levels.”

Do you have a tip on a science story that news week should cover? Do you have a question about the drought? Let us know at [email protected]

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