TNPCB is monitoring the inland water quality under two major programmes namely Global Environmental Monitoring System (GEMS) from 1984 and Monitoring of Indian National Aquatic Resources (MINARS) from 1988 at 32 stations along the four major rivers i.e. Cauvery, Tamiraparani, Palar and Vaigai and three lakes i.e. Ooty, Kodaikanal and Yercaurd in Tamil Nadu. Subsequently, CPCB has sanctioned 23 additional water quality monitoring stations under the 11thplan period during November 2010 and the monitoring was started from December 2010. At present 55 stations are being monitored by TNPCB.The programmes are funded by the CPCB, Delhi.
Under MINARS programme, the rivers Tamiraparani, Palar and Vaigai and the lakes Udhagamandalam, Kodaikanal, Yercaud ,Veeranam, Porur, Poondi, Pulicat and Redhills are being monitored. Under GEMS and MINARS programmes the river Cauvery is being monitored.
The Cauvery river is a major river in the State which drain more than one third of the State. This river has been identified as a major river for studying the impact of pollution caused by various activities of the domestic and industrial sectors. The quality of Cauvery river water is being monitored at 33 stations along the river under GEMS (4 stations) and MINARS (29 stations). These stations were selected on the basis of the location of outfalls of industrial effluents, municipal domestic sewage and other outfalls.
The physico-chemical and biological parameters are analysed for all the monitoring stations. Sampling is carried out based on the frequency prescribed by Central Pollution Control Board, Delhi and analysis is done at the Advanced Environmental Laboratory, Salem.
The water quality of the Thamiraparani river is being monitored on a frequency prescribed by CPCB, Delhi at 12 places. The physico-chemical parameters and biological parameters are analysed in the District Environmental Laboratory at Tirunelveli.
The water quality of river Palar is being monitored every month with one monitoiring station at Vaniyambadi municipal head works. The analysis of water samples is done in the AEL at Chennai, for physico-chemical and biological parameters.
The water quality of the Vaigai river is being monitored by collecting the samples once in six months from the collection well of Thirubuvanam head works and analysed in the AEL at Madurai for physico-chemical and bacteriological parameters.
Under MINARS programme, 8 important lakes of Tamil Nadu at Udhagamandalam, Kodaikanal, Yercaud, Veeranam, Porur, Poondi, Pulicat and Redhills have been identified and monitored by collecting samples on monthly basis.
In order to monitor the water quality of river Noyyal and Kalingarayan canal on continuous basis in the textile industrial belt of Tiruppur and Erode districts, TNPCB installed online continuous water quality monitors at three locations each in Noyyal river and Kalingarayan canal. These stations monitors pH, total dissolved solids, dissolved oxygen on continuous basis. Similarly TNPCB installed three stations in river Thamirabarai. These stations are functioning from October, 2014.