Spring 2009 potentiometric map of the Middle Trinity Aquifer in Groundwater Management Area 9, central Texas
Abstract
The Trinity Aquifer is the primary groundwater source for a variety of needs throughout
the Texas Hill Country. Groundwater Management Area 9 (GMA-9) is composed of nine
Groundwater Conservation Districts (GCDs) within the Texas Hill Country that are
tasked with managing groundwater resources. Recent State law requires Districts to
periodically meet to discuss the future availability of groundwater within the aquifers of
GMA-9. Increasing water-supply demands have raised concerns about the availability of
groundwater in the Texas Hill Country. In particular, the Middle Trinity Aquifer is the
primary aquifer for water-supply needs. At an early 2009 GMA-9 meeting, it was
discussed that a potentiometric (water level) map of the Middle Trinity Aquifer
constructed during the ongoing drought would provide useful information. All GCDs in
the GMA agreed to participate and send the authors water-level data collected from the
Middle Trinity Aquifer during the Spring of 2009.
Groundwater levels and potentiometric surface maps provide critical information about
the hydrologic relationships of recharge, discharge, and storage within an aquifer, and the
direction of groundwater flow. This report contains historic potentiometric maps and a
new Spring 2009 potentiometric map representing moderate drought conditions within
the Middle Trinity Aquifer of the central Texas Hill Country. The purpose of this report
is to provide a foundation of information and data for future hydrogeologic investigations
and evaluations of water resources. These maps and data will be useful for computer
modeling, sustainable yield determinations, and resource protection.