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Sediment is shrinking Lake Powell’s storage

Lake Powell

Lake Powell on the Colorado River has lost nearly seven percent of its storage capacity since it was built in 1963. KNAU’s Melissa Sevigny reports, that’s due to sediment washing into the reservoir.

The finding comes from a new high resolution survey of Lake Powell’s underwater topography. Scientists at the U.S. Geological Survey collected sensor data to make the three-dimensional map.

USGS hydrologist Casey Root spoke about the work at a webinar. He says, "One of the takeaways that we found from our surveys is that largely Lake Powell is losing storage capacity in a consistent manner," at a rate of about 33 thousand acre-feet of water a year. Root says the data can’t be used to estimate the total life of the reservoir, but it will inform water forecasts and Glen Canyon Dam operations.

Chris Cutler of the U.S. Bureau of Reclamation says it’s the first survey of its kind since 1986. "However, I would go out on a limb and say with the data that USGS has provided being such high quality, I can see that we might be interested in doing this survey on a more frequent basis moving forward."

Lake Powell is now about a quarter full. The water has dropped to a record low level due to a decades-long drought, worsened by the warmer temperatures from global climate change.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.