Water plays a vital role in sustaining and regulating the health of ecosystems and societies. Natural variability and human driven alterations to the hydrologic cycle (i.e. water quantity) drive complex dynamics within human-hydrologic systems and pose challenges to understanding and managing the resource. With respect to water quality, natural geogenic contaminants (e.g. arsenic, fluoride) and anthropogenic contaminants (e.g., microbial pathogens, PFAS, lead) threaten the health and well-being of society and ecosystems. This session will highlight research that addresses historic and emerging problems concerning water quantity or quality through transdisciplinary science. Presentations involving citizen science or community engaged research are encouraged, as are those that demonstrate convergence of methods or theory across fields.