Snowmelt Could Flood Western Communities

For all the advantages that record snowpacks offer regions susceptible to summertime drought, a sudden warming of temperatures could soon release millions of gallons of water into river channels and narrow canyons, flooding cities and towns throughout the American West.

Experts and officials fear for communities of all sizes. Thousands of people living in river towns scattered across Wyoming sit far from major sources of help, while California’s aging levee system could leave the state’s capital susceptible to a Hurricane Katrina-scale flood. –ARK

The New York Times:

Thanks to a blizzard-filled winter and an unusually cold and wet spring, more than 90 measuring sites from Montana to New Mexico and California to Colorado have record snowpack totals on the ground for late May, according to a federal report released last week.

… Late spring is a volatile time in the mountains, when freezing temperatures can turn overnight to heat waves and thunderstorms. And every day that the snows do not go gently down the stream raises the possibility of melting into late June and even July, when sudden mountain downpours can set off flash floods, dangerous even without a freight of snow behind them.

… Hydrologists, meanwhile, are cheering what they say will be a huge increase in water reservoir storage for tens of millions of people across the West. Lake Mead and Lake Powell, two huge dammed reservoirs on the Colorado River battered in recent years by drought, are projected to get 1.5 trillion gallons of new water between them from the mammoth melt.

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