A Study of Water Quality for Sungai Kedah during High and Low Tides

Sungai Kedah is the main river in Kedah with total length approximately 7.5 km2 from Kampung Balek Hutan to Alor Setar city before discharged to the sea. The size of the Sungai Kedah basin is approximately 3605 km2. The objectives of this study are to establish the pollutants profile along Sungai Kedah during high and low tides based on physical and chemical parameters. The analysis involved in-situ measurement (pH) and laboratory analysis (DO, TSS, BOD, COD and AN). During the high tide, the concentration of pollutants for pH is 7.04, TSS is 97 mg/L, BOD is 5.91 mg/L, COD is 64 mg/L and AN is 1.96 mg/L. During the low tide, the concentration of pollutants for pH is 6.92, TSS is 184 mg/L, BOD is 9.27 mg/L, COD is 89 mg/L and AN is 2.63 mg/L. Along Sungai Kedah, there are residential areas, agricultural areas, recreational park and squatters located at Alor Setar city, and Simpang Kuala wet market which are directly and indirectly affect the water quality of Sungai Kedah during high and low tides. Overall, the quality of the Sungai Kedah for the upstream is in Class II, the middle and downstream flow is in Class III.