Water Pollution in a Natural Stream and Its Impacts on Society and Environment: A Review of Studies on Meda Ela, Sri Lanka

Abstract: Meda Ela which originates from Kandy Lake and runs through Kandy city is considered to be one of most polluted tributaries of Mahaweli River. The objective of the study was to critically review the published research findings related to Meda Ela pollution to existing problems, research gaps and the means to rectify the situation. The review was carried out under the categories of socio-economic background, land use changes, sources of pollution, solid and waste water disposal, water quality, cost due to water pollution, economic benefits and major stakeholders and their interactions of Meda Ela. Study identified a very high urbanization rate in the watershed during the last decade compared to previous 30 years. Major point sources include the hospital, bus stand, railway station, central market and the residences on either side of Meda Ela. According to the literature, elevated pollution levels are reported during wet season and NO- 3, NH+ 4, PO3- 4, suspended solids, heavy metals, DO, BOD and COD showed above threshold limits. This is an indication of non-point source pollution which is responsive to hydrological conditions. Impacts of water pollution include vector borne diseases such as Dengu and Chickengunya, bad odour, flash floods and contamination of shallow groundwater with heavy metals. The social and management setup in the watershed is very complex since many stakeholders are involved in polluting and managing Meda Ela. The analysis revealed that the relationship among different stakeholders is highly diverse and as a result, their contribution to control water pollution in Meda Ela is also very different. Hence, a strong connection should be established between community and other stakeholders to develop an efficient and effective management plan to safeguard Meda Ela stream and its watershed