Evaluation of Eutrophication Indicators in Slim River Lake, Perak – Malaysia

This study investigated the trophic state of Slim River Lake, and evaluated its water quality according to National Lake Water Quality Criteria and Standards, (NLWQS). Water samples were collected twice per month from August 2017 to July 2018 in three sampling stations around the Slim River Lake. The tested water quality parameters include water temperature, total nitrogen, total phosphorus, chl-a, chemical oxygen demand and cyanobacterial cells number. The rainfall and air temperature data from August 2017 to July 2018 were obtained from the Malaysian Meteorological Department and the mean values were recorded as 252.95 ± 36.84 mm and26.96 ± 0.46 oC, respectively. The mean and standard error of water temperature, total nitrogen, total phosphorus, chemical oxygen demand, chl-a, cells number of cyanobacterial genera were29.52 ± 0.30°C, 5.32± 0.95 mg/L, 0.82± 0.12 mg/L, 31.89 ± 3.93 mg/L, 7.26±1.96 mg/L,18.3 × 10⁴ cells /mL, respectively. High levels of total nitrogen and total phosphorus were quantified during high rainfall period, thus imply the significant load from the storm water runoff. High cyanobacterial cell numbers were also detected, which indicated the occurrence of cyanobacterial bloom. The comparison of water quality parameters with NLWQS suggests a hypereutrophic condition in the study lake. In conclusion, the state of eutrophication in Slim River Lake poses potential health risks, and future changes in climatic factors will enhance this risk. Therefore, more attention and control by local authorities are needed to reduce the severity of eutrophication progression in this lake.