Managed Aquifer Recharge: A Proven Technology for Water Supply Resilience

Communities, governments, and agriculture worldwide are increasingly turning to managed aquifer recharge (MAR) as an important element of their water resources planning.A wide range of MAR approaches capture available water during wet periods, times of low demand, or water that would otherwise be lost, and move this water underground for later recovery or other benefits.MAR can address a diversity of issues, including water shortages, emergency supply, groundwater depletion, land subsidence, seawater intrusion, water-quality degradation, streamflow depletion, and endangered groundwater-dependent ecosystems (Alley and Alley 2026).Given the growing interest in MAR, this issue of Groundwater builds on a previous special issue dedicated to MAR in 2022.Much has happened in the intervening period, including continuation of an historic, extended drought in the southwestern United States, implementation of plans mandated by California's Sustainable Groundwater Management Act with many highly dependent on MAR, explosive growth of data centers with accompanying concerns about meeting their demands for water and energy, and increased interest in capturing storm and flood waters, as well as the use of recycled wastewater for MAR applications.The articles in this issue cover a range of issues associated with MAR.Among these are applications of MAR in karst aquifers, applications in mining, effects of mineralogy on PFAS fate and transport, uncertainty-based ensemble MAR modeling, application of airborne electromagnetic (AEM) data to reduce model uncertainty, the use of shallow, small-diameter drywells in the Midwest,