The seasonality of nutrients and sediment in residential stormwater runoff: Implications for nutrient-sensitive waters

The discharge of excess nutrients to surface waters causes eutrophication, resulting in algal blooms, hypoxia, degraded water quality, reduced and contaminated fisheries, threats to potable water supplies, and decreases in tourism, cultural activities, and coastal economies. An understanding of the contribution of urban runoff to eutrophication is needed to inform management strategies. More broadly, the seasonality in nutrient concentrations and loads in urban runoff needs further analysis since algal blooms and hypoxia are seasonal in nature. This study quantifies the variation of nutrients and sediment in stormwater runoff across seasons from four urban residential sewersheds located in Columbus, Ohio, USA. An average of 62 runoff events at each sewershed were sampled using automated samplers during stormflow and analyzed for nutrients and total suspended solids (TSS). Spring total nitrogen concentrations had a significantly (p