The civic body appears to have woken up to the possibility of defunct fountains in Salt Lake turning into mosquito breeding sites and triggering a dengue outbreak.

On Wednesday, water was drained out from some such fountains. In places where water could not be drained out, the Bidhannagar Municipal Corporation’s vector control teams sprayed larvicide and released guppy fish that feed on mosquito larvae.

Metro had on Tuesday reported that several fountains — installed on the Central Park promenade in the run-up to the FIFA U-17 World Cup and the Calcutta Book Fair — had turned into breeding grounds for mosquitoes after the accumulation of rainwater.

Krishna Chakraborty, the Salt Lake civic body mayor, said multiple teams comprising three members had been sent to the fountains.

“A truck-mounted machine has been sent to drain out the water. Civic workers could not drain out water from a few fountains inside parks because the water would have flooded the area, the police said.

“They sprayed larvicide in the accumulated water at the base of these fountains. We have released some guppy fish and will release some more as a natural way to counter mosquitoes,” Chakraborty said.

The machine is used to desilt manholes and sewers. Powered by a pump, it can be used to drain out water as well, a civic official said.