A constructed sea stream in Yeongdo, Busan, Republic of Korea is mostly static due to the raised stream bed and tidal characters and receives domestic wastewater nearby, causing consistent odor and sanitary problems. Bioaugmentation of a microbial consortium (BM-S-1) has been proposed as an effective and economical restoration technology to restore the polluted stream ecosystem. The purpose of this study was to elucidate whether bioaugmentation of the microbial consortium could lead to clean-up of the polluted sea stream and its ecosystem restoration. The microbial consortium activated on site was augmented into the most polluted sites (Sites 1, 2 and 3) on a weekly basis for a year. Water and sediment quality was monitored in terms of DO, ORP, COD, T-N, T-P, SS, and Chl-a. Microbial community analysis of the sediments was performed through pyrosequencing. A significant reduction in COD, SS and T-N of water column occurred by 58.1%, 51.1 % and 45.7%, respectively. Chl-a concentration also decreased in all the test sites except station 2 (ca. by 55.5%), indicating the restoration occurred. COD removal rates of the sediment in Site 2 and Station 4 were 51.1% and 74.2%, respectively, demonstrating the remediation of the polluted sediment. Microbial community cluster analysis showed that the community structures in Sites 1, 2 and 3 after bioaugmentation were differently grouped from those before the augmentation. This indicates that the sea stream restoration was due to the treatment with the microbial consortium. One of the dominant microbial populations in the sites before the treatment was sulfate reducers while the dominant ones after treatment were Psychrilyobacter atlanticus and Flavobacteriaceae. It was concluded that the sea stream restoration was triggered by augmentation of the microbial consortium, leading to a systematic restoration of the ecosystem.