The Edwards Aquifer comes to the surface at San Marcos Springs

The Balcones faults broke and moved layers of limestone. Water now moves fast through the cracks and caves. In Hays County, some of it comes back up at San Marcos Springs. It then forms the San Marcos River.

Rain, dry weather, and pumping can change the water level and spring flow. A long dry spell may show up in both a well and Spring Lake.

The Edwards and Trinity are two separate aquifers. They also have different local rules. Use a parcel map to learn which aquifer and water district apply to a well.