Water Resources in South Central Texas...Where Does Our Water Come From?

The South Central Texas Region includes parts of six major river basins (Rio Grande, Nueces, San Antonio, Guadalupe, Lavaca, and Lower Colorado) and overlies the Edwards-Balcones Fault Zone, Gulf Coast, and southern parts of the Trinity, and Carrizo-Wilcox Aquifers. In addition to these water resources, the area also overlies two minor aquifers (Queen City and Sparta Aquifers).

Springs also serve as a significant water resource in the South Central Texas Region. The two most noteworthy springs are the Comal and San Marcos Springs, which both contribute to flow in the Guadalupe River. The San Marcos Springs have the greatest flow dependability and environmental stability of any spring system in the southwestern United States. Constancy of its spring flow is apparently key to the unique ecosystem found in the uppermost San Marcos River. Comal Springs, located in New Braunfels, serve as the source for the Comal River, which is a tributary of the Guadalupe River. Unlike the San Marcos Springs, Comal Springs are more responsive to drought conditions and ceased flowing in June of 1956 in response to severe drought conditions.