Annually, the scale of agricultural areas in Korea were being reduced as the lands were converted to
other land uses. While the rate of productivity were either being maintained or increased, the pollution load from
these areas were still greater in magnitude. Although the levels of pollutant concentration released in the agricultural
watersheds were minimal, the combined quantities mostly from diffuse sources were high. As a consequence, the
Ministry of Environment (MOE) in Korea adopted the use of free water surface (FWS) flow constructed wetlands to
reduce the pollutant loadings emitted from agricultural watersheds for the improvement of water quality and
protection of aquatic ecosystems. In this study, a constructed wetland treating stream water in an agricultural
watershed was monitored since April 2009 subsequent to its completion in December 2008. Satisfactory performance
was achieved for TSS, BOD and TP with 26%, 28% and 39% pollutant removal rates, respectively. In addition, the
effluent water quality was improved and achieved compliance the national water quality criteria. Results of this
study can be useful to establish design parameters and employ proper removal techniques of similar natural
treatment systems for future implementation in the country.
Keywords : Agricultural area, Non-point source, Free Water Surface, Removal efficiency