Continuous monitoring and discrete water-quality sampling were coupled in a karst aquifer to assess drivers and timescales of water-quality change. Water-quality data included environmental tracers of groundwater age (tritium [3H], tritiogenic helium-3 [3He-trit], sulfur hexafluoride [SF6], carbon-14 [14C], and radiogenic helium-4 [4He-rad]). All water quality data is available from the U.S. Geological Survey NWIS database (U.S. Geological Survey, 2019). Groundwater ages were estimated by calibration of environmental tracers to lumped parameter models of groundwater age for multiple samples collected at six groundwater wells. The final estimates for mean groundwater ages ranged from less than 10 to greater than 700 years and provide insight into timescales of aquifer vulnerability. This data release includes five Microsoft Excel tables detailing these data (each table is also provided as a tab-delimited text file): Table_1_TXETN_AgeInterpretations: Table containing dissolved gas modeling results, environmental tracer concentrations, and lumped parameter modeling results. Table_2_TXETN_DissolvedGasModeling: Table containing dissolved gas modeling results. Table_3_TXETN_ComputedTracerConcentrations: Table containing computed tracer concentrations. Table_4_TXETN_14CAdjustments: Table containing Carbon 14 adjustments. Table_5_TXETN_Abbreviations: Table containing definitions for all abbreviations found in tables 1 through 4.