As Planet Warms, US Watersheds Go Thirsty

Nearly 1 in 10 watersheds have out-stripped water supply, with trend expected to worsen as climate heats up

A shocking one in ten U.S. watersheds is in a state of "stress" as the nation-wide demand for water outstrips nature's ability to provide, with this trend expected to worsen as the climate continues to warm, an alarming new study from the University of Colorado at Boulder finds.

"By mid-century, we expect to see less reliable surface water supplies in several regions of the United States," said the study's lead author, Kristen Averyt, associate director for science at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder.

The researchers evaluated water supply and need for all the 2,103 watersheds in the continental U.S. and found that 193 are already in a state of stress, meaning they simply do not have enough surface water to meet the demand.

They also evaluated extreme water stress from 1999 to 2007 and used this data to predict future patterns, and the prognosis is not good. "[T]he lowest water flow seasons of recent years--times of great stress on rivers, streams, and sectors that use their waters--are likely to become typical as climates continue to warm," a statement about the research reads.

In most parts of the United States agriculture is the biggest drain on water supply. However, large cities, as well as power plants which require water for cooling, can also have a large role in depleting watershed supply. These developments leave the U.S. west particularly vulnerable, because the margin between supply and demand is very small in a region dependent on imported and stored water.

Authors warn that the water crisis will only deepen as global warming worsens. "Future projections of water supplies and demands vary regionally and locally, but it is clear that climate change stands to increase national water demands and diminish national water supplies," the study reads.


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