US EPA

EPA is announcing the availability of this final report prepared by the Safe and Sustainable Water Resources (SSWR) Research Program, located within the Office of Research and Development, with support from Eastern Research Group (ERG). This report is a summary and synthesis of scientific and technical literature on enhanced aquifer recharge (EAR) using stormwater. It is based on a search and screening of published literature conducted during summer and fall of 2020. The goal is to summarize the current state-of-the-science of information leading to best practices for EAR using stormwater. Topics addressed include factors affecting recharge volumes, risks (particularly of water quality degradation), what current science suggests about best practices, and knowledge gaps that, if filled, will help inform recommendations for safe, effective EAR using stormwater. The report is technical and does not address policy or regulatory issues.

The intended audiences for this report are local and state planners, managers and engineers engaged in the development and implementation of strategies for enhanced aquifer recharge of stormwater; or anyone charged with developing and implementing stormwater, water reuse, urban resilience or sustainability related policies and practices that include consideration of enhanced aquifer recharge of stormwater.

Groundwater aquifers throughout the U.S. are being overused and depleted. EAR refers to the intentional recharge of aquifers, and includes goals and practices collectively referred to as managed aquifer recharge (MAR), aquifer storage and recovery (ASR), artificial recharge and other terms. There is growing interest in EAR as a way to augment drinking water supplies, replenish groundwater and restore streamflow.

This report focuses on one aspect of EAR, the intentional recharge of aquifers using stormwater from developed lands (as opposed to agricultural/rural). In these areas, EAR dovetails with traditional stormwater management. Stormwater often contains chemical and microbial contaminants, however, and thus carries the risk of contaminating receiving aquifers. There is a need for improved understanding of best practices for effective, safe EAR using stormwater in different development and hydrogeologic settings.

EPA scientists and their collaborators have conducted a technical literature review and synthesis of current state-of-the-science of information leading to best practices for enhanced aquifer recharge (EAR) using stormwater. The report examines the factors that influence the performance of EAR systems, and can help to inform recommendations for safe, effective EAR using stormwater in different development and hydrogeologic settings.  

U.S. EPA. Enhanced Aquifer Recharge of Stormwater in the United States: State of the Science Review (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-21/037F, 2021.