The document discusses the Ontario Geological Survey's (OGS) work conducting 3D mapping of surficial aquifers in Ontario. The OGS is mapping regional aquifers to address issues like contaminated municipal water, inform legislation around source water protection, and characterize aquifer vulnerability. Mapping methods include fieldwork, geophysics, drilling, and developing conceptual geological frameworks. Final products include 3D models of sediment packages, thickness and elevation maps, cross-sections, and applications for groundwater management, protection of ecosystems, and scientific studies.