BLOG: 10 Cool Things About Groundwater

by Jennifer Wemhoff, Groundwater Foundation

Groundwater is a unique resource, in that we can't see it. In honor of this week's National Groundwater Awareness Week, here are 10 cool things about groundwater.

• Groundwater is the water that fills the cracks and crevices  in beds of rocks and sand beneath the earth's surface. Groundwater is recharged when water soaks into the soil from rain or other precipitation and moves downward. Groundwater is generally considered a renewable resource, although renewal rates vary greatly from place to place according to environmental conditions.

• The aquifer in the U.S. is the Ogallala, underlying 250,000 square miles under eight states (Texas, Oklahoma, Kansas, Nebraska, South Dakota, Wyoming, Colorado, and New Mexico). Scientists guess that it could take 6000 years to naturally refill the aquifer if it were ever fully depleted.

• There's a lot more groundwater on Earth than surface water, to the tune of 20 to 30 times more than all U.S. lakes, streams, and rivers - combined!

• There's a lot of water on Earth, but only 1 percent of it is useable; 99 percent of that is groundwater!

• Groundwater provides much of the flow of many streams. The USGS estimates that about 30 percent of U.S. streamflow is from groundwater (although it is higher in some locations and less in others).

• The United States uses nearly 80 billion gallons per day of fresh groundwater for public supply, private supply, irrigation, livestock, manufacturing, mining, thermoelectric power, and other purposes.

• The temperature of shallow groundwater in the U.S. ranges from 44°F in north central areas to approximately 80°F in Florida and southern Texas.

• Groundwater is an important part of the hydrologic cycle. When precipitation hits the ground, it can take many paths. It can be absorbed by plants; stored on the surface in a lake, river, stream, or ocean; evaporated due to the sun's energy; absorbed into the soil temporarily; or pulled by gravity through the soil to be stored for years as groundwater.

• India has the most water wells in the world, with 21 to 25 million wells. The U.S. is second with 15.9 million wells and China has 3.4 million.

• Irrigation accounts for the largest use of groundwater in the U.S. Over 53 billion gallons of groundwater are used daily for agricultural irrigation from 407,923 wells to help feed the world.

Groundwater is truly amazing, and needs our protection. Get started today!