Lakes are considered to be one of the most productive and biologically rich inland surface water eco systems. In Tamil Nadu State, under Monitoring of Indian National Aquatic Resources (MINARS) programme funded by Central Pollution Control Board (CPCB), the water quality of 8 major lakes (i.e) at Ooty, Kodaikanal, Yercaud, Pulicat, Poondi, Red Hills, Veeranam and Porur are monitored by Tamil Nadu Pollution Control Board (TNPCB) on monthly basis by collecting water samples. The lakes in hill stations (i.e) at Ooty, Kodaikanal and Yercaud are monitored since 1988. The other lakes are monitored since December 2010. The monitoring report reveals that the lakes are generally meeting criteria for Class-C Drinking water source with conventional treatment prescribed by CPCB. However the level of Total Coliform, Fecal Coliform and Biochemical Oxygen Demand were found high in Ooty lake. BOD was found to be more than the criteria level in Kodaikanal, Yercaud and Porur lakes. This is mainly due to mixing of sewage and contaminated surfacerunoff into lakes.