Lake Powell rises 20 feet after Southwest floods

Storms that swept through the U.S. Southwest in late October and early November have pushed Lake Powell up more than 20 feet from its mid-September low. The rise dwarfs the gains from this year's snowmelt, according to Martin Hoerling, a climate scientist at the University of Colorado, Boulder. Despite the surge, the lake, which is the second-largest reservoir in the nation, remains just over a quarter full. As of Friday, 15 of the lake's 17 boat launches were still unusable.

The flooding stems from the El Niño climate pattern, which has intensified rainfall across the region. Hoerling noted that the wet weather offers an unexpected boost to water supplies that had fallen to record lows during a yearslong megadrought. He estimated that floodwaters and additional rain could add more than 1.2 million acre-feet of water to the lake. That volume is enough to support roughly 4 million average families for a year.

Local communities have seen immediate benefits from the wet weather. In Pagosa Springs, Colorado, more than 10,000 people were under water restrictions before storms dumped about 7 inches of rain in October. Town manager David Harris said those restrictions are now lifted. He described the storm as destructive but noted a silver lining in the improved start to the winter snowpack at higher elevations.

In northern Arizona, Upper Lake Mary has received more than 3 billion gallons of water since early October. Brian Huntzinger, the water production manager for Flagstaff, stated that the lake supplies up to 40% of the city's water. He said the recent storms deposited the equivalent of more than two years of water into the town's surface supply. This buffer is helping an operation that relies heavily on underground aquifers. Huntzinger added that the system might overflow before snow begins to fall.

Water officials in central Arizona are managing the influx of rain by releasing water from two nearly full dams into the Verde River. Bo Svoma, principal meteorologist at the Salt River Project, said this action is necessary because heavy floodwaters trapped in homes have gushed into streams that feed the river. The release prompts water to flow into the river's normally dry stretch in metro Phoenix.

Despite the improved conditions, the region remains in drought. Jack Schmidt, a professor at Utah State University who studies the Colorado River, said the U.S. Bureau of Reclamation is unlikely to change water release schedules until snowpack peaks around April. Mary Carlson, a spokesperson for the Bureau, acknowledged that conditions have improved but said considerable uncertainty remains. Under the current federal plan, California, Nevada, and Arizona will reduce water use by 1.25 million acre-feet annually over the next two years.