Responding to landowner concerns about potential changes in several dozen lakes near Edmonton, Alberta, a small team of citizens developed a water sampling program that ran from 2020 to 2023. The team knew a lot about limnology, had a feeling that the hummocky glacial terrain was important, but knew little about the mystic realm of the subsurface. Partnering with a hydrogeologist, they agreed to collect water samples that might shed light on groundwater dependence. Across two years, the same 42 lakes were sampled and analyzed for stable isotopes of water and radon-222 in addition to the suite of chemical, limnological and ecological analyses to document lake health and trophic state. As it turned out, water chemistry and isotopic measurements were largely explained by the position of a lake within the local groundwater flow system. Rather than develop an isotopic mass balance model, a simple metric to express the likelihood of groundwater dependence allowed the data collected to tell the story: with a map of the water table as a backdrop, total dissolved solids, oxygen-18, and radon-222 values illustrate where lakes might be more dependent on groundwater. These results were similar to the spatial pattern of trophic state, indicating that groundwater dependence could be a key factor responsible for lake ecological status. By taking a few additional samples, the team of citizens discovered that groundwater has a role in lake health, which contributed to discussions between landowners and decision makers on how to best manage land use in this diverse landscape.