Central Pollution Control Board in collaboration with Karnataka State Pollution Control Board is executing National Water Quality Monitoring Programme (NWMP) comprising 63 stations in the State. The monitoring is done on monthly basis in selected stretches of rivers. The monitoring network covers 19 Rivers. Presently the water quality monitoring network is operated under two programmes viz., Global Environment Monitoring System (GEMS- 5 locations) and Monitoring of Indian National Aquatic Resources System (MINARS- 58 locations).
Water samples are being analysed for 28 parameters which includes of 9 core parameters, 19 Physico-Chemical and Bacteriological parameters along with field observations. Besides this, 8 trace metals and 15 pesticides are analysed once in a year to assess the water quality.
Water Quality at a Glance
The water quality stretch is evaluated based on the criteria of designated best use and activities in the river. The monitoring locations where in one or more parameters are exceeded are identified as polluted, and requires action for restoration.
The water quality monitoring results are analysed with respect to the indicator of oxygen consuming substances (Bio-chemical demand) and indicator of pathogenic bacteria (total coliform and faecal coliform). The result of such analysis shows 60% consistence in one class ( C- class) , 16% improvement (B-Class) and 24% degradation (E-Class) in water quality.
The quality of water in maximum stretches of 16 rivers out of 19 belongs to C – Class, indicating that water is fit for drinking only with conventional treatment followed by disinfection. The water in the river Nethravathi belongs to A-Class, which is suitable for drinking after disinfection, while the water in Lakshmanthirtha, Cauvery and Arkavathi conforms to E-Class at 1 station (D/s of Hunsur town), 2 stations (Ulsoor lake, & Hebbala valley near Mandya) &, 2 stations (D/s of kanakapura, T.G. Halli reservoir) respectively, suitable only for irrigation, industrial cooling and controlled waste disposal.