Groundwater is a critically important source of water in the U.S., supplying fresh water for drinking supplies, agricultural irrigation, and streams, rivers, and ecosystems. However, groundwater is becoming increasingly depleted in most aquifers around the country, with impacts including shrinking aquifer storage capacities, land subsidence (and associated impacts like higher flood risk), and declining freshwater resources for communities and ecosystems. To mitigate and reverse the depletion of groundwater storage in local aquifers, many communities are turning to managed aquifer recharge (MAR) and aquifer storage and recovery (ASR). MAR and ASR practices vary depending on local geology, groundwater and recharge water composition, local land use practices, and water use requirements. Implementing MAR and ASR requires careful planning to both maximize groundwater replenishment and protect groundwater supplies from contamination.