The Malavoor vented dam slightly diluted on Sunday following a chemical spray by Karnataka State Pollution Control Board (KSPCB).

According to Rajashekar Puranik, Environment Officer at the board, about 1,000 litres of hydrogen peroxide was sprayed on the water from 4 p.m. to 6.30 p.m. on Saturday. It acted as an oxidiser to increase the dissolved oxygen level in the stagnated water making it diluted.

He told presspersons at the dam site on Sunday that as a result of the chemical spray, pollutants in the stagnated water have diluted and its black colour has diminished. A preliminary report from the National Institute of Technology-Karnataka (NIT-K), Surathkal, has said that the dissolved oxygen level in the stagnated water was below one mg per litre against the normal 3.5 mg per litre.

Mr. Puranik said that the NITK, the board and the College of Fisheries would submit three reports on the contents in the polluted water to know the reasons for pollution. The reports are expected in three days.

He said that nothing could be categorically said without obtaining the reports. To questions, he said that a natural drain from Baikampady Industrial Area and another from Mangalore Special Economic Zone areas joined the river downstream of the dam. At the same time, another stream in the upper reaches of the dam from Pachchanady and Manjalpade areas joined the river.

However, when a team of presspersons with Mayor Kavita Sanil, Mangaluru City Corporation Commissioner Mohammed Nazir, Mr. Puranik and other officials of the corporation and the board visited the dam on Sunday, crystal clear water was found flowing in the stream which joined the river in the upper reaches of the dam from Pachchanady and Manjalpade areas.

Mr. Puranik said that the board officials had on Tuesday last smelt hydrocarbon in the stream which came from the SEZ industrial areas which joined the river downstream the dam near Kenjar.

The smell was within a one-kilometre radius from the bank of the river. But he suspected that it might have evaporated and not joined the river.

Claiming that the board had never pointed fingers at the corporation for the pollution, he said that a preliminary report from the NIT-K had found traces of organic contents in the polluted water. It could have come from any stream, he said.