Responding to questions raised by two members of the Parliament on polluted river stretches in the country, minister of environment, forest and climate change Harsh Vardhan said the Central Pollution Control Board (CPCB) in association with the state pollution control boards monitors the river water quality through a network of monitoring stations under the National Water Quality Monitoring Programme.

CPCB in its report in 2010 identified 150 polluted river stretches in the country, based on BIO-chemical Oxygen Demand (BOD) levels, a key indicator of organic pollution.

In a subsequent report published by CPCB in February 2015, 302 polluted river stretches were identified on 275 rivers. The minister attributed the increase in polluted river stretches to the incline in number of rivers being monitored and the denser water quality monitoring stations, which went up from 1,085 in 2010 to 1,275 in 2015. He also cited increase in pollution loads primarily due to rapid urbanization as another reason.

In Tamil Nadu, seven river stretches along the Bhavani, the Cauvery, the Palar, the Sarabanga, the Thamirabarani, Thirumanimuthar and the Vasista were identified as being highly polluted. Most of these polluted stretches fall in the districts of Salem, Vellore, Erode, Namakkal and Tirunelveli.

The state has seven major rivers and a network of more than 100 distributaries.

The minister said to control discharge of industrial effluents, the CPCB and other state pollution control boards are taking a series of initiative to ensure compliance under the Water (Prevention and Control of Pollution) Act, 1974 and the Environment (Protection) Act, 1986. To improve the monitoring of compliance, directions have been issued to specific industries to install online 24x7 effluent and emission monitoring devices. Steps have also been taken to promote low waste concept in various water polluting industries by recycling treated effluents.