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The Green Life: Ask Mr. Green: Who's Using Our Water?

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April 12, 2013

Ask Mr. Green: Who's Using Our Water?

Mr. Green is Bob SchildgenHey Mr. Green,

Which uses more water and how much, industry or the general public?

Frank, in Dubuque, Iowa

Industry, primarily for electric power plants and irrigation, draws a lot more water than the general public. Of the total of 410 billion gallons per day drawn in the United States, around 29.5 billion were used directly by households, or about 7 percent of the total, according to the latest data from the U.S. Geological Service. Electric power plants required around 200 billion gallons per day for steam and cooling, while irrigation soaked up 128 billion gallons.

However, if we add the indirect residential water consumption that results from residences using about 38 percent of U.S. total electric use of 3.750 trillion kilowatt hours per year, then the total residential use shoots up to around 105.5 billion gallons per day, or roughly 25 percent of the total. This may be one of the best-kept secrets of our times, but a rather telling example of truth of that famous statement by the Sierra Club’s illustrious founder John Muir: “All things are hitched.” Meaning that if we had the good sense to cut our electrical consumption, our water use would diminish correspondingly.  

It’s also important to remember that not all water consumption is equal, because of differing rates of evaporation, which means that some processes return more water to the ecosystem than others. So irrigation, for example, loses about twice as much water to evaporation than vanishes in generating electricity. And while hydroelectric is a wonderful low-carbon source of power, because of evaporation in the large lakes behind the dams, 35 times as much water is lost to evaporation than in conventional thermal-power generation.  

Consider thirsty California: More than 50 percent the total withdrawals of 45.7 billion gallons per day in California are for irrigation, while 28 percent go to power. Yet, to the dismay of many environmentalists, the state's governor, Jerry Brown, is pushing for a tunnel project costing anywhere from $12 billion to $50 billion to shunt water from the Sacramento River to the south. Now since Brown has long been a noted prophet of lower expectations, you’d think the guy would be putting more emphasis on efficient irrigation, a drastic reduction in our electrical consumption, and solar/wind power instead of this dubious boondoggle. We’re talking a rate of 15,000 cubic feet per second, and, yes, John, because everything is hitched, even more electrical power would be needed to pump it, and then—more water to cool the power plants! It may require a third prophet to deal with this madness: Rube Goldberg himself.

—Bob Schildgen


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 --illustration by Little Friends of Printmaking

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