In Sunday's Washington Post, an opinion piece showed up that illustrates an important point about water use in America: It isn't all about drought. We're still a growing country, and as population increases, so too will the need for water.

In the United States, we constantly fret about running out of oil. But we should be paying more attention to another limited natural resource: water. A water crisis is threatening many parts of the country -- not just the arid West.
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In Florida, excessive groundwater pumping has dried up scores of lakes. In South Carolina, a paper company recently furloughed hundreds of workers because low river flows prevented the company from discharging its wastewater. That state's battle with North Carolina over the Catawba River has reached the U.S. Supreme Court. Water has become so contentious nationwide that more than 30 states are fighting with their neighbors over water.

Lake Superior, the largest of the Great Lakes, is too shallow to float fully loaded freighters, dramatically increasing shipping costs. North of Boston, the Ipswich River has gone dry in five of the past eight years. In 2007, the hamlet of Orme, Tenn., ran out of water entirely, forcing it to truck in supplies from Alabama.

Droughts make matters worse, but the real problem isn't shrinking water levels. It's population growth. Since California's last major drought ended in 1992, the state's population has surged by a staggering 7 million people. Some 100,000 people move to the Atlanta area every year. Over the next four decades, the country will add 120 million people, the equivalent of one person every 11 seconds.

But with most of our rivers already damned, most of our groundwater sources already tapped, aging infrastructure leaking billions of gallons of water a day and climate change affecting the distribution of rainfall, how can we continue to meet the need for water? We're just going to have to get smarter about how we use the resource. A lot smarter in fact.