Addressing Water Scarcity in Texas: Evaluating Stormwater Quality and Quantity for Managed Aquifer Recharge

The use of stormwater for enhancing aquifer recharge has emerged as an innovative method of addressing increasing water scarcity in Texas. However, there is limited information on the potential (1) volumes of stormwater available for capture and (2) impacts of enhanced stormwater on groundwater quality. Specifically, the relationships between stormwater contaminant loading and various controlling factors have not been well characterized in Texas, along with the feasibility of stormwater capture. In this study we used publicly available datasets of streamflows and water quality to identify and inform opportunities for enhanced stormwater recharge in Texas aquifers. Further, we evaluated the potential availability of stormwater for capture. To do this, we evaluated publicly available water availability models (to ensure compliance with water rights) and environmental flow recommendations to reduce downstream ecological impacts. Statistical analyses show that individual site characteristics such as land cover likely impact various stormwater quality parameters including nutrients, metals, and microbial contaminants. The exact composition of stormwater quality can vary depending on the monitoring station and combination of different event, watershed, and site characteristics. Case studies of water quality in various stormwater recharge structures show that interim storage and partial pre-treatment of excess stormwater before injection can prevent degradation of groundwater quality. Furthermore, unappropriated high magnitude flows are often co-located with depleted major aquifers in Texas, including the Texas Gulf Coast and Trinity aquifers, underscoring the potential for using flood water for managed aquifer recharge to support sustainable water resources. Accordingly, this study provides a foundation for using large publicly available datasets to better understand and inform opportunities for enhanced stormwater recharge in Texas.