Deep Groundwater Drilling, Central Texas

ABSTRACT

Lower Cretaceous aquifers dominate groundwater production throughout the Central Texas Hill Country. The aquifers have been referred to as the Edwards-Trinity and the Hill Country Trinity aquifers in published literature which lump individual aquifers into broad categories. This paper breaks out individual aquifers and aquitards into discrete mapping units and revises new stratigraphic interpretations and aquifer-aquitard relationships. These new interpretations are the result of a multi-year deep drilling research program across Kerr County in Central Texas sponsored by the Headwaters Groundwater Conservation District. A total of twelve wells were drilled across a 1,100 square mile area. Each well was drilled through the entire Cretaceous System into the underlying Paleozoic surface. All wells were lithogically and geophysically logged and a selected few were pump tested. Cross-sections and maps were constructed from this new data and incorporated into a series of new interpretations, which have regional implications. Isotope age dating of groundwater across the area from distinct aquifers is an ongoing portion of the research. The purpose of the research effort was to establish an index of wells and provide long term monitoring of aquifer levels as well as recharge, provenance, thickness and hydrodynamic flow regimes. Additional wells are planned for the ensuing years to follow.