I am concerned about SMRT's anti-flood measures (SMRT to roll out anti-flood measures at four more sites; Jan 25).

As the float switches at the Bishan storm water reservoir will activate the rainwater pumps only when water levels rise too high, does it mean that the reservoir may contain water at any point in time?

If so, wouldn't that create a conducive environment for mosquitoes to breed?

In July 2015, there were many dengue cases reported in Bishan Streets 22 to 25. In September 2016, Zika cases were reported in Bishan Street 12. These locations are roughly within 1km of Bishan MRT station.

I wonder if the National Environment Agency conducted any checks at the storm water reservoir during those periods?

More importantly, what are SMRT's measures to prevent mosquitoes from breeding there?

Ang Hak Heng