Lake Powell, the second-largest man-made reservoir in the US, has lost nearly 7 percent of its potential storage capacity since 1963, when Glen Canyon Dam was built, a new report shows.
In addition to water loss from an intense multi-year drought, the US Geological Survey and Bureau of Reclamation report found, Lake Powell was facing an average annual loss of storage capacity of about 33,270 acre-feet, or 11 billion gallons, per year between 1963 and 2018.
That’s enough water to fill the National Mall’s reflecting pool about 1,600 times.
According to the report, the reservoir’s capacity is being reduced due to sediment flowing from the Colorado and San Juan rivers. These sediments settle to the bottom of the reservoir and decrease the total amount of water that the reservoir can hold.
As of Monday, Lake Powell was about 25 percent full, according to data from the Bureau of Reclamation.
It’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 at least those conditions are expected to continue — if not worsen — in the coming months.
Lake Powell is a major reservoir in the Colorado River basin. Both Lake Powell and nearby Lake Mead, the nation’s largest reservoir, have been draining 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 level dropped to record lows, prompting mandatory water cuts for southern states -west that started in January.
And last week, Lake Powell fell below the critical threshold of 3,525 feet above sea level, prompting additional concerns about the water supply and hydroelectric power generation that millions of people in the West depend on for to electricity
The importance of the declining water supply along the Colorado cannot be overstated.
The system supplies 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 in the region, including rural farms, ranches and Native communities.
“It is vitally important that we have the best scientific information available like this report to provide a clear understanding of water availability in Lake Powell as we plan for the future,” Tanya Trujillo, assistant secretary for water and science at the Department of the Interior of the United States. , he said in a statement. “The Colorado River system faces multiple challenges, including the effects of a 22-year drought and the increasing impacts of climate change.”