The promise and challenges of managed aquifer recharge, a proven water-supply strategy that is benefitting communities around the globeGroundwater is essential for a healthy environment and thriving communities, but around the world, aquifers are drying up. Over-pumping, climate change, and pollution threaten to deplete this vital resource, with dire consequences for people and landscapes. One of the most promising solutions is to purposefully direct water back into the ground—a technique known as managed aquifer recharge, or MAR. Banking on Groundwater explores the global potential of this important strategy while helping water managers navigate political, social, and environmental pitfalls.Though simple in concept, MAR raises thorny questions in practice. How does harvesting water upstream affect the places and people downstream? Will climate change alter the water sources available for MAR? Could recharge introduce contaminants into groundwater? How can those who recharge the water be assured of the ability to recover it? Through illuminating case studies, William Alley and Rosemarie Alley address these and other dilemmas while showing how MAR can help solve a host of problems, including water shortages, seawater intrusion, water-quality degradation, streamflow depletion, and the endangerment of ecosystems that depend on groundwater.Examining various approaches to MAR in a wide variety of settings across the United States and around the world, Banking on Groundwater is essential reading for water managers, policymakers, educators, and other professionals engaged in water conservation.