IISc warns of heavy metals in Kolar lakes

The samples drawn from Kolar lakes, filled with treated water from Bellandur STPs as part of the ambitious KC Valley project, have revealed high presence of heavy metals beyond critical limits.

The findings by an expert team led by Prof T V Ramachandra of the Centre for Ecological Sciences, IISc, were submitted to the Karnataka High Court on Friday when the court heard the matter and ordered the government to resume pumping of water to Kolar lakes from the treatment plants in KC Valley.

According to the report, a copy of which is with DH, IISc scientists have traced and analysed heavy metal content in water samples drawn from two outlets of KC Valley sewage treatment plants (STPs) in Bengaluru and two lakes of Kolar — Lakshmisagara and Narasapura lakes.

As part of the study, the expert team collected samples from multiple locations at the pumping unit and the two lakes. A detailed analysis revealed the presence of six heavy metals — chromium, cobalt, copper, zinc, cadmium and lead — beyond permissible levels at two treatment outlets of KC Valley STP and the two lakes filled with the treated water. The report also warned authorities that the heavy metals may enter the food chain causing severe health hazards.

The report said that the water pumped into Kolar lakes from Bellandur has already resulted in foam formation and that the diversion of this partially-treated wastewater with foam into Kolar lakes has harmed aquatic organisms and humans exposed to those contaminants. DH had reported the death of aquatic organisms in Lakshmisagara lake on July 26.

The water in Narasapura lake, which was once used for domestic purposes, cannot be used now as its has profuse growth of toxic plants which damage liver and nerve cells.

Advocate Prince Isac, counsel for the petitioners, said the report submitted by the IISc states that the treated water from Bellandur STP contains heavy metals. “The high court has ordered the state government to submit reports on tested water samples of Kolar lakes in 15 days. If there is any change in the quality of water samples, the court will take a further decision about the pumping of water into the lakes,” he said.

The high court, based on the government report on tested samples and IISc scientists' report, will hold a final hearing after three weeks.