Karnataka disputes polluted river list, ​Central panel suggests joint survey

Bengaluru: A committee of experts monitoring the pollution of rivers in Karnataka has directed a joint inspection by state and central agencies in January 2025 to resolve the conflicting claims over the number of polluted rivers in Karnataka.

The Central Monitoring Committee under the Union Ministry of Jal Shakti has been monitoring the work by states and Union Territories to rejuvenate over 350 polluted rivers by arresting the flow of untreated sewage.

This includes regular monitoring of the infrastructure, including the sewage treatment plants (STPs), provided to treat the wastewater running to the rivers.

Based on data submitted by Karnataka State Pollution Control Board, the Environment Department of Karnataka has been requesting the committee to drop three rivers -- Aghanashini, Sharavathy and Gangavali -- from the list. The department has also pointed out that another river, Thenpennai, was located in the boundary of Tamil Nadu and not Karnataka.

The committee, in its recent meeting, discussed Karnataka’s claim. “According to  the state, only 10 river stretches are polluted, therefore a joint inspection is proposed in January to ascertain the number of polluted river stretches. Further, it was highlighted that the Thenpennai river is in Tamil Nadu and not in Karnataka. CPCB may take note of it,” the committee noted.

A senior official in the Central Pollution Control Board said the inspection can happen after Karnataka submits the necessary documents. “Any state that seeks dropping of a river from the polluted river stretches needs to show first, water quality reports of 24 consecutive months meeting the standard criteria. If the water quality fails to meet the standards even for one month, the river will remain in the list of polluted stretches,” he
said.

“This is done because samples drawn during monsoon months usually show less pollutants due to the exponential increase in the water flow. It would help the case of the state to provide details of the infrastructure built to stop the flow of sewage into a river they want delisted,” he added.

The CPCB classifies water into A, B, C, D and E with class ‘A’ fit for drinking and class ‘E’ the polluted water fit for cooling, controlled waste disposal and irrigation. For a river to be removed from the list of polluted stretches, the biochemical oxygen demand (BOD) should be below 3 mg/litre and the most portable number (MPN) of the coliform bacteria should be below 500 per 100 ml.

KSPCB Member Secretary H C Balachandra said the correction in the list will help focus resources on the remaining stretches of polluted rivers. “We have sought joint inspection by the CPCB. We have the required data to show that the river quality has improved. The data has also been submitted to the committee,” he said.