CHENNAI: In a big setback for Tamil Nadu’s efforts to lend credence to its allegation that Cauvery’s water was polluted by the discharge of upstream sewage from Karnataka, the Central Pollution Control Board (CPCB) has turned down a plea by the State government to use Bureau of Indian Standards’ Tolerance Limits for Inland Surface Waters. The board refused to entertain the plea as the parameter was withdrawn in 1989.
Tamil Nadu wanted to test Chemical Oxygen Demand (COD) and Total Dissolved Solids (TDS), and for fecal coliform to be included for analysing water quality. Now, the sampling will be done for four water-quality criteria: dissolved oxygen, biochemical oxygen demand, PH and total coliform. This comes after CPCB held a second meeting with officials of Karnataka and Tamil Nadu late last month after the Supreme Court asked it to file a report within six months over Tamil Nadu’s claim that Karnataka was polluting Cauvery.
Sources said that initially in the first meeting, it was decided to conduct three consecutive rounds of joint sampling at two locations on Cauvery. The sampling was to be conducted during August, September and October.
However, due to incessant rainfall during the months of August and September in Karnataka and in neighbouring parts of Tamil Nadu, only one round of sampling could take place. During the meeting, the Tamil Nadu government had requested to continue sampling once in a month upto December and extend it to March next year to cover both post monsoon and lean season, which was agreed upon.
Both States will jointly carry out sampling at two points, and sampling results will be provided by both Karnataka and Tamil Nadu state pollution-control boards to the regional directorate and CPCB. Thereafter, based on results, water quality trends will be analysed for each location.
The mapping of Cauvery by Karnataka, which was proposed during the first meeting held in August, has been dropped. It was suggested that Karnataka map sources of pollution along Cauvery and its tributaries to enable effective action against sources of pollution. But Karnataka has objected, stating that the bone of contention was whether or not the river is polluted at the point when it reaches the Karnataka-Tamil Nadu border.
It was also learnt that CPCB is unlikely to adhere to the deadline to file a report within six months; the report will be delayed till March 2018, sources said. According to a petition filed by Tamil Nadu, the physical condition of Cauvery before it enters the state is in danger as several of its tributaries and minor rivers have become non-existent or have turned into sewage-carrying canals.
Indiscriminate discharge of sewage and effluents is killing the river’s natural ecosystem. Tamil Nadu has quoted the test reports of CPCB of samples collected from Pennaiyar, a 2km stream of the inter-state border, between September 2014 and February 2015. The samples were tested at CPCB’s zonal laboratory in Bengaluru.
The tests revealed that biochemical oxygen demand (BOD) varied from 19.7mg/litre to 32mg/litre, and fecal coliform varied from 38,400 to 7.8 lakh MPN/100ml. BOD in inland surface water should be less than 3mg/litre after conventional treatment and disinfection, the petition said.
Murky waters
Cauvery has the eighth largest catchment area among 14 major river basins.
The river and its tributaries pass through Bengaluru, Mysore and Mandya in Karnataka; and Mettur, Coimbatore, Erode, Tiruchirapalli and Kumbakonam in Tamil Nadu.
CPCB states that water abstraction and other activities have affected quality from Hogenakkal to Grand Anicut, and in Hebballa, Vrishabhavati, Bhavani, Noyyal and Amravati tributaries.
TN government in its petition alleged that no attempt was made by Karnataka to set up effluent treatment plants or reverse osmosis systems.