The U.S. has a growing water supply problem, according to a new study.

Nearly 1 in 10 of the nation's watersheds—areas of land that contain runoff from rivers and streams—are stressed to the point to where demand for water exceeds the natural supply.

"There is a lot of pressure on our water supply, especially In the western part of the country," said Kristen Averyt, associate director for science at the Cooperative Institute for Research in Environmental Sciences, and lead author of the report released this month.

"As the population grows, so too does demand. We expect to have less surface water supplies in several areas of the U.S. by 2050," she added.

The report analyzes supplies and demand over the past 10 years for the 2,103 watersheds in the continental U.S. and found that 193 were stressed, meaning their supply of water for use was less than the demand.

The report said that the western U.S. is most vulnerable to water stress because the area relies on stored water as well as imports of water from rivers and streams—and the difference between demand and supply is so small that a slight shift in either can trigger shortages.

Because agriculture requires the most water—some 70 percent of all water use in the U.S.—it's a major contributing factor to water stress in the country, said the report. And the report states that in certain sections of the U.S., the use of cooling water by electrical power plants places yet another big demand on water supplies.

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A survey by the research group EIRIS found that under current business conditions, water demand will outstrip supply by 2030—and will potentially put $63 trillion of global gross domestic product at risk by 2050.



"Along with agriculture, the use of water for electrical supply from power plants could force us into a tipping point on water demand," Averyt argued.