THE TRINITY AQUIFER: FEELING THE PRESSURE

Historically, the extensive use of the Trinity aquifer(s) has resulted in relatively large artesian pressure declines, especially near population centers. While these declines have lowered well bore water levels several hundred feet in confined portions of the aquifer(s), coherent trends in water table levels are not apparent from measurements taken in outcrop zones. The general stability of water levels in unconfined areas implies that the total amount of groundwater in storage has remained relatively unchanged through time. Similarly, the results obtained from historical simulations using the Trinity/Woodbine Groundwater Availability Model suggest that the reductions in artesian pressure have not significantly impacted the amount of water in aquifer storage.

Although comparatively steady for many years, it is likely that Trinity pumpage will increase over the next several decades in response to increased demands associated with population growth and petroleum production in northern Central Texas. This expected escalation in groundwater use coupled with the common perception that depletion of the Trinity is imminent, has prompted some local stakeholders and State agencies to promote increased regulation in northern Central Texas. As part of this effort, the region's groundwater conservation districts have adopted management criteria that restrict artesian pressure declines in the Trinity units. However, evaluation of predictive simulation results suggests that limiting drawdown in confined portions of an aquifer is an ineffective method of long-term aquifer management.