When it comes to making practical management decisions or formulating policy with respect to managing aquifer supplies, including water quality and water quantity issues, dealing with uncertainty is a constant and inevitable part of decision making. Science is frequently called upon to help us understand or reduce uncertainty, but efforts to “advance our understanding” of ground water and aquifer systems often seem to point to an increasing “complexity.” The panel discussion will explore the following question: “How and in which areas can ground water science and technology most effectively assist decision-makers in understanding, identifying and incorporating the relevant uncertainty in setting priorities for additional studies, management activities, investment or developing new policy?”