US Lake Powell reservoir capacity shrinks as winter approaches

Between 1963 and 2018 the US Geological Survey and the Bureau of Reclamation found that Lake Powell had an average annual loss in storage capacity of 33,270 acre-feet, or 11 billion gallons per year, due to water loss due to an intense multiyear drought.

That's enough water to fill the Reflecting Pool on the National Mall about 1,600 times.

The reservoir's capacity is shrinking because sediments are flowing in from the Colorado and San Juan rivers, according to the report. The sediments settle at the bottom of the reservoir and decrease the amount of water the reservoir can hold.

According to the Bureau of Reclamation, Lake Powell was about 25% full as of Monday.

National Oceanic and Atmospheric Administration drought experts said last week these conditions are expected to continue in the coming months, if not worsen. Lake Powell is an important reservoir in the Colorado River Basin. Both Lake Powell and nearby Lake Mead, the nation's largest reservoir, have drained at an alarming rate. In August of this year, the federal government declared a water shortage on the Colorado River for the first time since Lake Mead's water level plunged to unprecedented lows, triggering water consumption cuts for states in the Southwest that began in January. Lake Powell dropped below the critical threshold of 3,525 feet above sea level last week, sparking further concerns about water supply and hydropower generation millions of people in the West rely on for electricity. The significance of the dwindling water supply along the Colorado can't be overstated. More than 40 million people live in seven Western states and Mexico and receive water from the system. Lake Powell and Mead provide a critical supply of drinking water and irrigation for many of the region, including rural farms, ranches and native communities. It is important 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, Tanya Trujillo, assistant secretary for water and science at the US Department of Interior, said in a statement. The Colorado River system is facing a number of challenges, including the effects of a 22 year-long drought and the increased impacts of climate change.