Cauvery Basin: Short Paragraph on Cauvery Basin!
With almost 95 per cent abstraction of water, the Cauvery is one of its most exploited rivers of India.
The Cauvery has watered agricultural lands of Tamil Nadu, Karnataka and Kerala. Sharing of the Cauvery waters has been the bone of contention between the two contending states, viz., Tamil Nadu and Karnataka.
High rate of application of chemical fertilizers and insecticides in agricultural field results in discharge of large quantities of chemicals in the river water, thereby polluting the river to a great extent. Coffee production in the districts of Coorg, Hassan and Chickmagalur contributes heavily to the BOD level of the river water which ranges from 2,000-4,000 mg/1. Coffee industry contributes 4730 tonnes of BOD load in each season.
There are 14 Class I cities and 17 Class II towns in the catchment area of the Cauvery basin. These cities and towns generate about 750 million litres of wastewater and 3500 tonnes of solid waste every day. Important Class I cities are in Karnataka (Bangalore, Hassan, Mandya and Mysore) and Tamil Nadu (Salem, Erode, Coonoor, Tiruppur, Valparai, Dindigul, Tiruchchirapalli, Kumbakonam, Thanjavur and Coimbatore).
The industrial activity is very high in this basin, particularly in the Bangalore area in Karnataka and Methur as well as Coimbatore in Tamil Nadu, followed by districts of Mysore and Mandya in Karnataka and Periyar and Salem in Tamil Nadu.
A total of 61 industries in Karnataka and 1,139 in Tamil Nadu contribute heavily to the pollution load, especially during the lean flow period of the year. In Tamil Nadu, some water-intensive industries such as textiles, sugar mills, paper mills, chemical units, engineering units, tanneries, etc., have come up which contribute to the pollution load of the river.
Noyyal is one of the most polluted tributaries of the Cauvery River. It is polluted by 800 odd dyeing and bleaching units located at Tiruppur. This 173 km long river carries untreated sewage and industrial effluents from the towns of Coimbatore and Tiruppur for most part of the year.