Loon populations are increasingly challenged by a combination of environmental and human-driven stressors that interact in complex ways. Legacy and emerging contaminants, such as mercury (Hg) and per- and polyfluoroalkyl substances (PFAS), respectively, pose known (in the case of Hg) and unknown (in the case of PFAS) reproductive risks. Water quality affects the bioavailability of both classes of pollutants. In the Adirondacks, major water quality changes are underway with a warming climate, including decreases to lake water clarity, which directly impacts loon health via changes in foraging success, and indirectly via increases in Hg bioavailability. Here, we leverage the extensive water quality and food web monitoring planned for 2026-2028 through the Survey of Climate and Adirondack Lake Ecosystems (SCALE), to assess questions about drivers of contaminants in loons, the economic and cultural icon of the Adirondacks. This project will enhance knowledge of temporal and spatial predictors of Hg and PFAS in loons, build a comprehensive dataset as the basis for advanced statistical models that assess loon health in a changing climate, and provide state leaders with water quality information relevant to humans.