From the aspect of theories and practice of remediation of eutrophicated waters the world over, the methods used in recent years for remedying eutrophicated waters and their effects have been elucidated. The theories and methodology for haptophyte remediation of eutrophicated water is getting gradually mature with on-scale practicing of the technologies of open water confined rearing, efficient mechanical harvesting and complete biomass utilization. The risk of wild spreading of floating plant Eichhornia crassipes and failure of timely removing the plant expansion causing secondary pollution of the waters is efficiently evaded. Through controlled cultivation of E. crassipes, TN and TP in the water of the Dianchi Lake was significantly reduced from 13.47 and 1.34 mg•L-1 in the inflow to 2.93 and 0.10 mg•L-1 in the outflow of the lake, respectively. All the findings indicate that lake eutrophication can be effectively controlled as long as careful planning and proper bio-technology, like controlled cultivation of, E. crassipes, is adopted.