The Edwards Aquifer — one of the most prolific karst aquifers in the United States — is located right here in south central Texas. Explore and discover the features that make this aquifer one of the most porous and permeable aquifers around.

The Edwards Aquifer is a karst aquifer, a term describing a landscape with soluble rocks like limestone, forming caves, sinkholes, and other natural fractures, resulting in highly permeable terrain.

The Edwards Aquifer began forming over 100 million years ago, while south Texas was covered by a warm shallow ocean. The remains of organisms accumulated in layers, later forming the limestone as the seas regressed. During the Cretaceous Period, dinosaurs roamed the landscape and natural forces went to work, carving the landscape and forming the aquifer we know today.

Beginning along the Southern edge of the Edwards Plateau, the Drainage Area funnels water into streams and creeks that flow south toward the Recharge Zone.

Water originating from the Drainage Area soaks into the porous and permeable Edwards Limestone comprising the Recharge Zone of the Aquifer. Here the water sinks, or infiltrates underground, entering the interconnected conduits or passageways that makeup the Edwards Aquifer. The amount of total recharge can be calculated each year using stream gauges and rainfall estimates.

Historical data representing the rate of recharge within the aquifer for each year measured in thousands of acre feet. The middle segment of the aquifer represents the recharge zone. The bluer the color, the more water is being added.

A caver descends more than 150 feet to the bottom of the sinkhole, following a similar path that rainfall and runoff would take.

As the water flows deeper underground, flowing generally north and east towards discharge points via thousands of water wells, and some of the largest spring systems in Texas.