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Surface water resources have played an important role throughout history in the development of human civilization. About one third of the drinking water requirement of the world is obtained from surface sources like rivers,canals and lakes. But, these sources serve as the best sinks for the discharge of domestic as well as industrial wastes. This unscientific disposal of wastes has caused immense problems not only to human beings but also to the aquatic environment world wide. In Sri Lanka, this problem started long back but intensified during the last few decades and now the situation has become alarming. Consequently, studies on the major river ecosystems indicate that the major rivers in Sri Lanka are grossly polluted.Pinga Oya a major tributary of Mahaweli River, is more popular as one of the most polluted running water system in Central Province, Sri Lanka. Hence, an investigation was carried out to examine the water quality through various physico-chemical and microbiological parameters,and Chironomid larvae to determine the status of the lotic waterbody. This study is especially useful to university students and water professionals or anyone who are interested in Lotic Ecosystem.

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Nandana Anurudda Karunarathna was born in 1976 in Kurunegala, Sri Lanka.He is lives in Sri Lanka.He is a gradute in B.Sc.(Hons)in Biological Science at University of Sri Jayewardenepura,Sri Lanka.He completed M.Sc. in Environmental Science at University of Peradeniya, Sri Lanka.His research interests are Limnology and Water Resource Management.

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