Heavy rainfall and flooding across the U.S. Southwest in late October and early November have begun to recharge reservoirs that reached record lows during a long-term drought. While the storms caused evacuations and property damage, hydrologists report the runoff is providing a boost to the region's storage systems.
The region has been experiencing a megadrought, and last winter's snowfall resulted in minimal recharge during the typical spring and summer melt period. Experts attribute the recent shift in weather to El Niño, a climate phenomenon that has intensified precipitation across the West. Experts indicate these weather patterns may continue for several months, potentially further increasing water supplies.
Lake Powell has risen more than 20 feet from its low point in mid-September. Martin Hoerling, a climate scientist at the University of Colorado, Boulder, estimated the inflow could total over 1.2 million acre-feet, which he estimated is enough to support approximately 4 million average families for one year. Despite these gains, the lake remains just over 25% full, and 15 of its 17 boat launches were still unusable as of Friday, November 6.
In Pagosa Springs, Colorado, where 7 inches of rain fell in October, local officials lifted water restrictions that had affected more than 10,000 residents. In Arizona, Upper Lake Mary received more than 3 billion gallons of water since early October, providing what water production manager Brian Huntzinger described as a buffer for the city of Flagstaff. In central Arizona, water managers at the Salt River Project began releasing water from nearly full dams into the normally dry Verde River in metro Phoenix.
For individual households and small-business owners, the rainfall brought a reprieve from local emergency drought measures, but federal water policy is unlikely to change immediately. The U.S. Bureau of Reclamation has stated it is unlikely to adjust planned water releases from Lake Powell until the snowpack peaks, which typically occurs around April. A federal plan currently requires California, Nevada, and Arizona to reduce their collective water use by 1.25 million acre-feet annually over the next two years, an amount comparable to filling 600,000 Olympic-sized swimming pools.
The effects of these storms include legal developments as Nevada and Arizona continue to challenge the federal water reduction plan in court. The improved reservoir levels provide a buffer but do not end the regional drought or the necessity for new infrastructure, such as the proposed expansion of a dam on the Verde River to capture future storm runoff. The Bureau of Reclamation will evaluate snowpack conditions around April to determine if adjustments are necessary.