How big is an aquifer?
The size of an aquifer depends on the amount of rainfall and the composition of the underground rock and soil. The world’s largest aquifer is in the United States. Called the Ogallala, it spreads under eight western states, from South Dakota to Texas. The Ogallala formed millions of years ago and is still supplying water to cities, businesses, and farms. Unfortunately, people are using water from the Ogallala faster than it can be naturally replenished, and the water table is falling.
