Large-scale airborne electromagnetic (AEM) surveys represent a substantial investment in regional subsurface characterization, yet many legacy datasets remain underutilized for hydrogeologic interpretation due to historical limitations in analysis, variable data quality from earlier sensor technologies, and limited applied interest at the time of acquisition. Recent advances in computational workflows and growing interest in groundwater applications now enable these datasets to be revisited. An extensive AEM survey acquired in 2011 over the Calgary–Lethbridge Corridor in southern Alberta provides a case study for reassessing the hydrogeologic value of legacy geophysical data. In this study, we reprocess and reinterpret this dataset using modern approaches designed to improve resolution of hydrostratigraphic architecture and reduce uncertainty in regional aquifer models. The workflow includes updated noise mitigation and quality control, followed by complementary inversion strategies—smooth, sharp, and reference-based—to better delineate aquifer boundaries and estimate the depth to bedrock. To support direct hydrogeologic interpretation, we develop field-scale relationships between electrical resistivity and sediment type using co-located driller’s logs. These relationships are used to transform inverted resistivity models into sediment-type and coarse-grained fraction profiles, enabling assessment of aquifer continuity and connectivity at regional scales. The results demonstrate that revisiting legacy AEM data with modern tools can significantly enhance conceptual understanding of aquifer systems without the need for new data acquisition. Overall, this work illustrates the enduring value of archived airborne geophysical datasets for regional groundwater characterization and provides a transferable framework for groundwater assessment in sedimentary basins.