Performance Monitoring of a Stormwater Wetland Best Management Practice

Abstract

This paper presents the results from monitoring water quality inflows and outflows from a stormwater wetland best management practice. Multiple samples were taken during each storm event and were coupled with flow monitoring to develop pollutographs. During storm events, the wetland showed a removal efficiency of nearly 70 percent for total suspended solids, while dissolved components such as reactive phosphorus and chlorides showed little or no overall removal. A significant “first flush” can be seen during storm events, with large peak inflow concentrations. These high concentrations are reduced greatly by flow through the wetland. A parallel base flow study prelimarily shows approximately 60 percent removal of reactive and total phosphorus, and nearly 80 percent removal of total nitrogen. Chloride passed directly through the system for both storm events and baseflow. Overall, the levels of all nutrients and pollutants in both influent and effluent are well below recommended water quality standards.