Photograph by Karen Kasmauski
Groundwater is the water that seeps into the earth and is stored in aquifers—areas of soil, sand, and rock that are capable of holding liquid. The water sits in between particles or in cracks and fissures. These saturated underground areas—some replenished by rain and snow, others not—can be found close to the Earth’s surface or hundreds of feet underground.
When you pass a natural spring spilling water from a mysterious source, that source is often groundwater. This underground H20 also makes its way into lakes and rivers and is often tapped by wells for drinking and irrigation supply.
Nearly 50 percent of people living in the U.S. get their drinking water from groundwater. But its biggest use is irrigation.
Threats to this underground source increase as population and development accelerate. Agricultural and urban runoff tainted with chemical pesticides and fertilizers seeps into groundwater sources, as does gas from leaking underground tanks. But the biggest threat? Overtapping this limited resource.
Taxed by political, economic, and development pressures, some groundwater sources are now facing depletion. The solution may rely on cooperation, often across political borders, and better management policies.
- The overpumping of groundwater is causing water tables to fall across large areas of northern China, India, Pakistan, Iran, the Middle East, Mexico, and the western United States.
- The United States is the world’s third largest irrigator (after China and India).
- The Ogallala Aquifer, which spans parts of eight states from southern South Dakota to northwest Texas, is steadily being depleted. The Ogallala provides 30 percent of the groundwater used for irrigation in the U.S., and as of 2005, a volume equivalent to two-thirds the water in Lake Erie had been depleted.
Did You Know?
Using satellite data, scientists have recently estimated that groundwater in India is being depleted across the country's north, which includes the its bread basket, to the tune of 1.9 trillion cubic feet (54 billion cubic meters) per year. As wells run dry, the nation’s food supply—as well as the livelihoods of the region’s 114 million people—are increasingly at risk.
More About Groundwater
Using innovative satellite technology, a new study finds that groundwater supplies in the Central Valley of California, the nation's fruit and vegetable bowl, are dwindling at an alarming rate.
Nearly a third of India is suffering from chronic rainfall shortages, and making up for it with "the world's largest groundwater mining operation."
Water budgets are badly out of balance, throwing many regions into water debt. The water depleted annually could feed 940 million people for a year.
Water-strapped countries are tapping ancient underground aquifers to stay afloat. But so-called paleowater won't last forever, experts warn.
Help Save the Colorado River
You can help restore freshwater ecosystems by pledging to cut your water footprint. For every pledge, Change the Course will restore 1,000 gallons back to the Colorado River.
Sandra is a leading authority on international freshwater issues and is spearheading our global freshwater efforts.
He's paddled the Colorado River from its headwaters to the delta in an effort to bring awareness to this mighty river at risk.
For more than 15 years, Osvel Hinojosa Huerta has been resurrecting Mexico's Colorado River Delta wetlands.
Change the Course Infographic
Check out this infographic and learn how you can conserve water and save the Colorado River, as well as other freshwater ecosystems.
Water Currents, by Sandra Postel and Others
Arizona's Verde River gets a boost from an innovative partnership.
Farmers in the Verde River Basin employ new technology to benefit a desert environment.
Funny viral video series hopes to get people thinking about the importance of water.