Joe McConnell
CNN
—
Lake Powell, the second-largest man-made reservoir in the United States, has lost nearly 7 percent of its potential storage capacity since Glen Canyon Dam was built in 1963, a new report says.
In addition to water loss from an intense multi-year drought, the U.S. Geological Survey and Bureau of Reclamation report found that between 1963 and 2018, Lake Powell suffered an average annual loss of storage capacity of about 33,270 acre-feet, or 11 billion gallons, per year.
That’s enough water to fill the National Mall’s Reflecting Pool approximately 1,600 times.
The reservoir’s capacity is shrinking because of sediment flowing from the Colorado and San Juan rivers, the report says. That sediment settles on the bottom of the reservoir and reduces the total amount of water the reservoir can hold.
According to Bureau of Reclamation data, Lake Powell was about 25 percent full on Monday.
That’s bad news for a region already facing water shortages and extreme wildfires due to drought. Drought experts at the National Oceanic and Atmospheric Administration said last week that those conditions are expected to continue, if not worsen, for at least the next few months.
Lake Powell is a major body of water in the Colorado River Basin. Both Lake Powell and nearby Lake Mead, the nation’s largest reservoir, have been drying up at an alarming rate. In August, the federal government declared a water shortage on the Colorado River for the first time after Lake Mead’s water levels plummeted to unprecedented lows, triggering mandatory water cuts for Southwestern states that began in January.
And last week, Lake Powell dropped below the critical threshold of 3,525 feet above sea level, raising further concerns about water supplies and hydroelectric power generation, which millions of people in the West rely on for electricity.
The significance of the declining water supply along the Colorado cannot be overstated.
The system provides water to more than 40 million people living in seven Western states and Mexico. Lakes Powell and Mead provide a critical supply of drinking water and irrigation for many people in the region, including rural farms, ranches, and indigenous communities.
“It is vital that we have the best available scientific information like this report to provide a clear understanding of water availability in Lake Powell as we plan for the future,” said Tanya Trujillo, assistant secretary for water and science at the U.S. Department of the Interior, in a statement. “The Colorado River system faces multiple challenges, including the effects of a 22-year drought and the growing impacts of climate change.”
