Integrating wetlands into watershed management: Effectiveness of constructed wetlands to reduce impacts from urban stormwater

Water detention and water storage during storm events, and water release during dry periods, are some of the main functions wetlands can provide in order to help reduce peak flow and increase low flow runoff into streams. However, wetlands can also be effective in retaining and remediating contaminants. Results of the case study on a constructed wetland that mitigates urban storm-water are discussed. The effectiveness of metal reduction in water is highly variable and not all metals are detained and reduced at the same rate. Concentrations of certain metals in the sediments were not sufficiently reduced, which remains a challenge that can likely be resolved by improving the wetland design. A sediment detention pond could be constructed before the runoff enters the wetland and the sediments accumulated in this pond would then have to be removed and treated on a regular basis. As urban development continues to encroach on hills and sloping terrain, the use of wetlands to regulate water flow and retain contaminants will became more viable.