The objectives of this research are to identify the pollutant sources location, analyse the pollution load and pollution load capacity parameter BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand) and TSS (Total Suspended Solid). QUAL2Kw method is applied in modelling process where main rivers are divided into nine reach with Sungai Sibayang (kilometre-86,629) as headwater and Mentuli…