The Cauvery river enters Tamil Nadu already polluted and Karnataka needs “vigilance” to counter further pollution, the Central Pollution Control Board told the Supreme Court this week. In a report submitted to the court on Friday, the pollution body cited the results of water quality tests it conducted over four months last year, The Times of India reported on Sunday.

The Tamil Nadu government had in 2015 filed a plea in the Supreme Court to stop Karnataka from allowing untreated sewage and effluents into the Cauvery river. In July 2017, the court asked the central pollution body to file a report in response to the plea.

The CPCB and the two state pollution control boards together tested water samples from the Cauvery and its tributaries Thenpennaiyar and Arkavathi between September and December 2017. The samples were taken near the border of Karnataka and Tamil Nadu.

Samples from the river Thenpennaiyar failed in all parameters they were tested on, in all four months. Levels of coliform and faecal coliform – which indicate bacteriological pollution – exceeded safe limits in September and October in the Arkavathi and in October in the Cauvery, the report said. Organic pollution was at unsafe levels in December in the Arkavathi and the Cauvery.

“River Thenpennaiyar is polluted and comprehensive plan of action is required for restoration of its water quality,” the report said. “The Arkavathi and Cauvery rivers were found to be polluted due to higher count of faecal coliform, attributed to open defecation, and requires vigilance from the concerned organisations in the state to prevent further pollution.”

“No state should let polluted water into another state,” an unidentified senior official of the Tamil Nadu government was quoted as saying. “Tamil Nadu will submit its remarks to the apex court for stringent action during the next hearing, scheduled after two weeks.”

On February 16, the Supreme Court ordered that the Centre set up a Cauvery Management Board within six weeks to ensure that its ruling to allocate the river water to the two states is implemented.

Karnataka voters worried about water supply, quality

Meanwhile, a survey released on Saturday said that improving the quality and supply of water in Karnataka were the most important concerns for voters. The state will have Assembly elections later this year.

The Karnataka Voter Survey 2018, by nonprofits Daksh and Association for Democratic Reforms, showed water supply and quality topped the list of concerns, ahead of electricity, schools and roads.