Power and water are interconnected and that has serious consequences for the American West as it grapples with climate change. By now, everyone knows you save energy by turning out lights. And you conserve water by taking shorter showers. But it's just as true that saving water may be one of the most effective ways to save energy—and vice versa . "It's a 'buy one, get one free' deal," said Douglas Kenney, a professor at the University of Colorado Law School and the editor of an upcoming book that explores the nexus of water and energy. In California today, just delivering water accounts for 20 percent of the state's energy consumption. It takes power to gather water, purify water, and distribute water, especially in places like southern California where water is piped hundreds of miles to supply Los Angeles' sprawling demands. Nationally, energy production sucks more water from freshwater sources than any other sector except agriculture. It takes water to create the power we use to drive our cars, transport our groceries, and run our toaster ovens. Virtually every source of electricity in a typical American home or manufacturing plant—whether it comes from hydroelectricity, coal, natural gas, nuclear, biofuels, or even concentrated solar—also requires water. Lots of water. That's a growing problem, because in many places, finding water for energy isn't easy— and it's bound to get tougher as energy demands soar and climate change alters hydrological cycles in already arid regions. The energy sector is the fastest-growing water consumer in the United States, according to a January 2011 Congressional Research Service report. Nationally, that's a challenge, but regionally it could be a calamity. As the Congressional Research report notes, "much of the growth in the energy sector's water demand is concentrated in regions with already intense competition over water." The connection between energy and water—and the precariousness of that link in the western United States—is exemplified in a gigantic plug of concrete stopping the muddy Colorado River above Las Vegas, otherwise known as Hoover Dam. At the ceremony inaugurating the Hoover Dam provided the two key ingredients—water and power—that freed the Southwest and southern California to go on a 75-year growth spurt. Lake Mead now supplies water to more than 22 million people, and it produces more than four billion kilowatts of electricity per year. The Colorado River, lifeblood of seven western states, is already as overdrawn as the federal treasury. Drought conditions during most of the 21st century have forced water managers to plan for a day when the region' s vast system of dams and reservoirs no longer have enough water to store. Already, utilities have to scramble to respond on days when everybody in Phoenix, Las Vegas and Los Angeles wants to crank their air conditioners during the same heat wave.

单选题 What does "vice versa" (Line 3, Para. 1) refer to?

单选题 Which of the following statement is TRUE?

单选题 It can be inferred from the passage that the Congressional Research Service report considers the U. S. energy sector______.

单选题 Which of the following can substitute for "overdrawn" (Line 1, Para. 6)?

单选题 The most appropriate title for this passage could be______.