Since 1987, the University of Delaware has prepared GIS-based Water Resource Protection Area (WRPA) mapping for New Castle County that serves to protect the quality and quantity of ground and surface water supplies as part of the Unified Development Code (UDC). The WRPA program is enabled under Section 10 (Environmental Standards) of the UDC for New Castle County. The intent of the ordinances is to protect the quality and quantity of surface water and groundwater supplies through the protection of environmentally sensitive areas important to the state’s water supply. Under the UDC, all development within recharge, wellhead, Cockeysville formation, and reservoir water resource protection areas are required to meet maximum impervious cover thresholds (20–50%) and may require groundwater recharge facilities, water monitoring, and water management facilities. Presently, over 20 percent of New Castle County’s land area is protected by the WRPA provisions of the UDC. UDWRC's 2022 GIS based mapping updates represent the sixth revision to the maps. These maps depict several data layers that represent the four main WRPA categories in New Castle County, Delaware–Cockeysville Formation, Wellhead WRPA, Surface Water WRPA, and Recharge WRPA. The maps serve as a guide for development and assist decision-making in New Castle County, Delaware. The WRPA data will soon be available for download at Delaware FirstMap and PDF versions of the maps are available on the UDWRC website.