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Managed Aquifer Recharge: A Proven Technology for Water Supply Resilience

Managed aquifer recharge (MAR) is “the purposeful recharge of water to aquifers for subsequent recovery or for environmental benefit,” a definition accepted broadly and by the NGWA MAR Work Group. Surface infiltration basins and well injection are the two main methods of MAR in the United States, although many other methods are being used, including in lieu recharge, bank filtration, dry wells, etc. At a time of widespread groundwater depletion and increasingly dramatic swings between wet and dry conditions, MAR can help provide water supply resiliency for communities and industry, small and large. Groundwater journal found it timely to devote a special issue to MAR, focused largely on North America to provide case studies, lessons learned, innovations, and some context on regulations of this important water management approach. This special issue supplements recently published international compendiums of MAR case studies, overview, and governance (Zheng et al. 2021; Dillon et al. 2022). MAR is not new by any means, having been practiced for decades and even centuries in some locales. Recharge water may be stored in a wide spectrum of confined and unconfined aquifer types, from unconsolidated alluvial deposits to karstic and fractured rocks. The current focus in many areas is on increasing and enhancing MAR to manage water supply through droughts and provide increased water supply reliability as demands grow and hydrology changes due to climate and human modifications of the land surface. In California alone, under the 2014 Sustainable Groundwater Management Act, new groundwater sustainability plans submitted to the state propose more than 2.5 million acre-feet (3 km3) of MAR annually, at a projected