OpenFlows PondPack is a software that allows users to model rainfall and runoff from urban and rural watersheds to design detention and retention facilities, outlet structures, and channels. It has an intuitive and easy-to-use interface that simplifies detention pond design while the robust calculation engine handles the complexity of interconnected pond modeling. It offers improved design productivity and delivery of high-quality pond design projects. The software provides simple step-by-step pond and outlet design, streamlined model building and management, and improved understanding of real-world situations. OpenFlows PondPack is a subset of OpenFlows CivilStorm and OpenFlows SewerGEMS.