It's a familiar drill to people living in drought-plagued parts of the country. Folks who live at an even-numbered address water the lawn on Mondays, Wednesdays and Fridays between 4 p.m. and 10 a.m. Odd-numbered addresses sprinkle on Tuesdays, Thursdays and Saturdays.
When things get really dry--as seems to be happening more often--there's no watering at all. Violators will be charged anywhere from $100 to $1,000 a day.
If water use restrictions like these bring to mind visions of the parched Great Plains or the arid Southwest, the headlines tell another story. In the summer of 2006, communities in two Great Lakes states--Minnesota and Wisconsin--issued total watering bans during dry periods. Ditto for areas in and around normally lush Atlanta, Georgia. From New England to California, municipal planners are dealing with serious concerns about future water resources.
The proverb says, "When the well is dry, we know the worth of water." In the United States, we are just starting to understand that water is a finite substance that must be protected. National Geographic warned us in October 1993, "All the water that will ever be is, right now." No matter how technologically advanced our water processing becomes, we can't do a thing to increase nature's fresh water. To meet the growing demand for water caused by population growth, food production and economic development, we must conserve, be creative and use what we have more efficiently.
Water, Water Everywhere
Water is humanity's most plentiful resource, covering almost 70 percent of the Earth's surface. But 97 percent of it is ocean water, too salty for drinking or for watering crops.
Of the 3 percent that is fresh water, most is locked in the ice caps of Antarctica and Greenland or in underground rock layers too deep to mine. A tiny fraction is found in bodies of water or beneath the soil in aquifers that can be tapped for wells.
As countries go, the United States is generously endowed with this precious resource. Annual precipitation here equals 4.2 trillion gallons. That's enough to cover the entire country with 30 inches of standing water. It's not all available as drinking water or for energy production, of course. Two thirds evaporates and transpires back to the atmosphere in what is called the hydrologic cycle. The remainder seeps into the ground or goes into the nation's lakes, rivers, reservoirs, and eventually oceans. It's a lot of water, 15 times what Americans currently consume. So how could there possibly be a supply problem?
The answer is twofold: demand and distribution.
Water doesn't always go where it's needed most. A downpour in Nevada doesn't help an Illinois farmer in the middle of a drought. A full reservoir in Texas is of no use to a depleted one in New York. As a general rule, droughts create local and regional shortages that are as unpredictable as local and regional weather. To date, no one has proposed pumping water cross-country in order to share the wealth.
Making matters worse, droughts are becoming more severe and widespread, according to the World Water Council. Expected climate change in coming years will make rainy seasons shorter and more intense in some regions, and droughts longer and more severe in others, the council warns.
Demand is rising, too, although less so in the United States than in newer industrialized nations. Blame irrigation, the great giver of life, which is responsible for virtually all of the growth in U.S. water demand in recent years. Farms need a lot of water. It takes eight gallons to grow a single, juicy tomato. Notably, industrial use of water has actually dropped since 1980.
Irrigation accounts for almost 40 percent of water use, the single largest use of fresh water in the United States. Irrigated acreage more than doubled in size from 1950 to 1980, then leveled off before increasing 7 percent …