How does the Edwards Aquifer work?

Meteorologist Sarah Spivey explains in depth

SAN ANTONIO – The Edwards Aquifer is responsible for providing millions of people from the Hill Country to San Antonio with freshwater every day. And although a lot of us know that the aquifer is our local source of water, very few understand exactly how the vast underground system works.

Beneath our feet is a layer of porous limestone called ‘karst.” Groundwater from rains fills this karst, and eventually, the pressure allows water to bubble up in the form of natural springs or fills man-made wells.

There are three main "zones" to the Edwards Aquifer system: the contributing zone, the recharge zone and the artesian zone.


The Contributing Zone:

The rolling hills of the vast Texas Hill Country make up the majority of the contributing zone, which is sometimes called the "drainage area." Here, rainwater trickles downhill, seeps underground or feeds local rivers and creeks until it spills into the recharge zone.

The Recharge Zone:

The recharge zone is quite literally where the aquifer gets recharged. Open caverns and the Balcones fault zone provide an entrance to the underground limestone that then carry groundwater into the artesian zone.

The Artesian Zone:

As recharge water fills the artesian zone, it builds immense pressure within the karst. In some places, this pressure is great enough to cause water to bubble to the surface in the form of natural wells and springs. Elsewhere, we dig wells to access the water.

WATCH: How does the aquifer work?

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About the Author:

Sarah Spivey is a San Antonio native who grew up watching KSAT. She has been a proud member of the KSAT Weather Authority Team since 2017. Sarah is a Clark High School and Texas A&M University graduate. She previously worked at KTEN News. When Sarah is not busy forecasting, she enjoys hanging out with her husband and cat, and playing music.