Abstract

Abstract Stormwater ponds are common features in urbanized landscapes because they enhance flood reduction and nutrient retention. With shallow depths and high inputs of organic matter, these systems can be highly productive with rapid oxygen depletion when thermally stratified or ice‐covered. However, most of our understanding of the biogeochemistry of stormwater ponds comes from the open water period. We explored under‐ice oxygen dynamics in 20 stormwater ponds in Madison, WI (USA) that were ice covered from late December to early March to investigate the drivers of bottom water oxygen saturation and the impact on the accumulation of carbon dioxide (CO 2 ) and methane (CH 4 ). Winter anoxia was driven by ice transmissivity, winter nutrient concentrations, and precedent summer productivity. Oxygen depletion led to overall higher concentrations of greenhouse gases in pond surface waters. This research enhances our understanding of winter pond biogeochemistry and its links to summer productivity.