Assessment of spatial variation in water quality: a case study at three surface water bodies in Galle Municipal Council area

Abstract

This study was conducted in two phases. In the first phase, a water quality analysis was conducted on Moragoda Ela, Kepu Ela and Mahamodara Lake. The results revealed that the water quality of the three water bodies was lower than the demanded quality of water for many usages. Moragoda Ela was identified to be the most polluted one. In the second phase, a detailed water quality analysis was carried out on Moragoda Ela. Mean values of COD and BOD5 were 127.5mg/L and 14.8 mg/L, respectively. Mean values of fecal and total coliforms were 47 and 23471 colonies/100 mL, respectively. Prevailing BOD5, COD and the total and fecal coliform content exceed the ambient water quality standards for inland waters in Sri Lanka. It is concluded that the water quality deterioration of all three water bodies may be attributed to the large number of industries, institutions and commercial establishments, high population density and the illegal community activities.