There are two parts of this study to determine pollutant export from stormwater ponds 1) phosphorus (P) and 2) cyanobacteria and cyanotoxins (HABs). High phosphorus concentrations can cause eutrophication in lakes. A traditional paradigm of watershed management has been that stormwater ponds capture and retain P, thereby serving as important practices for reducing P loads to downstream waterbodies. However, recent studies have documented the prevalence of internal P loading from stormwater pond sediments. Stormwater ponds are designed to capture P, thus high in-pond P concentrations from internal P loading is primarily problematic if the pond is exporting P downstream. This project aims to quantify export of total P and orthophosphate from different types of stormwater ponds (levels 1 3 from the Minnesota Stormwater Manual). A better understanding of which type of pond exports more will inform pond retrofit opportunities and potentially new pond design guidance to improve performance. HABs are a human and ecological health risk. Therefore, the second part of this study is to determine if the HABs that originate within a stormwater pond can be exported to downstream waterbodies, and if cyanobacteria and cyanotoxins can survive/persist after being discharged from the pond outlet and traveling through the stormwater conveyance systems. Both components of this study build upon the knowledge from studies Stantec has completed throughout the Twin Cities metro area over the last decade. If P and HABs are conveyed downstream, this study will inform stormwater management throughout the Twin Cities and likely lead to changes in pond design.