How an Aquifer Works
The unique geology of the Barton Springs segment of the Edwards Aquifer makes it a particularly fragile resource
In places where aquifers recharge slowly, groundwater resources are somewhat buffered from the short-term impact that surface water suffers: Even if your streams are gunked up, your springs may still flow clear. Not so in the Hill Country. The Barton Springs segment of the Edwards Aquifer is composed of hole-filled limestone that resembles Swiss cheese. The aquifer recharge zone is the area where this limestone is open to the surface, allowing rainwater to enter the aquifer with virtually no filtration. Some of what flows into the aquifer flows right back out of springs like the Barton in a matter of hours or days, so increased pollutants can show up quickly. A February 2005 report by the city of Austin found that pollutants in the springs had increased a significant amount over the last decade, and cited the Hill Country development boom as a possible reason.
This isn't to say that slow-recharging aquifers are immune to the effects of urbanization. When rainwater runs off the land rather than seeping into the aquifer, groundwater reserves are diminished so that wells run dry and springs stop flowing. And they, too, can be polluted over time. The unique geology of the Barton Springs segment of the Edwards, however, makes it a particularly fragile resource, one that requires extra vigilance if it is to be protected. Sidebar