Muhammad Haziq Jamil creator author. text my 2020 monographic eng xiv,126 pages : illustrations (some color) ; 30 cm. + 1 CD ROM Eutrophication was known as a process of the aggressive growth of algae on the surface of the water, as caused by excessive richness nutrients through surface runoffs. Every water body in the world will undergo the eutrophication process naturally, unfortunately, the presence of mankind activities such as agricultural and sewage runoff, wi ll speed up the process which caused a lot of environmental issues to the world. This study was undertaken ex-situ where the overall aim of this study is to treat the eutrophic man-made lake of KOTASAS lake water through following objectives; to identify the variation of physicochemical attributes KOTASAS lake water; Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), Oil and Grease through phytoremediation, to evaluate the potential removal of selected heavy metals; Manganese (Mn), Iron (Fe), Copper (Cu) and nutrients; Nitrate and Phosphorus using Eichhornia crassipes (water hyacinth) and Pistia stratiotes (water lettuce) and to find the correlations between sampling points and physicochemical attributes using IBM SPSS Statistics analysis. The method of analysis of lake water sample was referred by Standard Method for Examination of Water and Wastewater 23rd Edition (APHA). Then, statistical notation was conducted on the results obtained to identify the accuracy and validity of data, which in this case, ANOVA (one-way factor) and correlation were used. Referring to the statistical notation of (p<0.05), shows a conclusion on the significance of the result and variables were made. It was justified statistically that the data obtained for each treatment using different types of plants are valid and concise. As a result, it is found that water lettuce (WL) and water hyacinth (WP) have different nutrients and heavy metals removal efficiency but, in all cases, these phytoremediation agents exhibited nutrients removal efficiency from the range of 32% up to 57% followed by heavy metals removal efficiency from the range of 30% up to 78%. Mostly, WL exhibited great Nitrate and Phosphorus removal efficiency, 54.68%, and 57.24% followed by WH which was 32.39% and 33.39% respectively. Then, as for heavy metals, WL also showed higher removal efficiency for Mn, Fe, and Cu such as 51.59%, 78.99%, and 77.69% followed by WH which was 30.64%, 61.28%, and 58.58%. Finally, with this achievement acquired in phytoremediation technology employing to WL, it was the utmost importance for this technology to be implemented for larger scales in the future. Hence, WL was suitable to be used in controlling eutrophic lake due to its hyper-accumulating ability. specialized Muhammad Haziq Jamil Faculty of Civil Engineering Technology Thesis (Master of Science) -- Universiti Malaysia Pahang – 2020 Includes bibliographical references Faculty of Civil Engineering Technology Universities and colleges Dissertations Theses THE0009132(Local) UMP 220303 20251125110022.0 eng