Discharge of untreated and partially treated industrial and municipal wastewater from towns constitute major source of pollution in rivers and lakes. CPCB is monitoring water quality of various river stretches in the country including, inter-alia, River Ganga and Yamuna. Based on the monitoring, 150 polluted stretches have been identified along various rivers in the country. The Govt. of India through a study has identified 62 lakes across the country for conservation.